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Rodríguez-Castro L, Durán RE, Méndez V, Dorochesi F, Zühlke D, Riedel K, Seeger M. The long-chain flavodoxin FldX1 improves the biodegradation of 4-hydroxyphenylacetate and 3-hydroxyphenylacetate and counteracts the oxidative stress associated to aromatic catabolism in Paraburkholderia xenovorans. Biol Res 2024; 57:12. [PMID: 38561836 PMCID: PMC10983741 DOI: 10.1186/s40659-024-00491-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 03/20/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND Bacterial aromatic degradation may cause oxidative stress. The long-chain flavodoxin FldX1 of Paraburkholderia xenovorans LB400 counteracts reactive oxygen species (ROS). The aim of this study was to evaluate the protective role of FldX1 in P. xenovorans LB400 during the degradation of 4-hydroxyphenylacetate (4-HPA) and 3-hydroxyphenylacetate (3-HPA). METHODS The functionality of FldX1 was evaluated in P. xenovorans p2-fldX1 that overexpresses FldX1. The effects of FldX1 on P. xenovorans were studied measuring growth on hydroxyphenylacetates, degradation of 4-HPA and 3-HPA, and ROS formation. The effects of hydroxyphenylacetates (HPAs) on the proteome (LC-MS/MS) and gene expression (qRT-PCR) were quantified. Bioaugmentation with strain p2-fldX1 of 4-HPA-polluted soil was assessed, measuring aromatic degradation (HPLC), 4-HPA-degrading bacteria, and plasmid stability. RESULTS The exposure of P. xenovorans to 4-HPA increased the formation of ROS compared to 3-HPA or glucose. P. xenovorans p2-fldX1 showed an increased growth on 4-HPA and 3-HPA compared to the control strain WT-p2. Strain p2-fldX1 degraded faster 4-HPA and 3-HPA than strain WT-p2. Both WT-p2 and p2-fldX1 cells grown on 4-HPA displayed more changes in the proteome than cells grown on 3-HPA in comparison to glucose-grown cells. Several enzymes involved in ROS detoxification, including AhpC2, AhpF, AhpD3, KatA, Bcp, CpoF1, Prx1 and Prx2, were upregulated by hydroxyphenylacetates. Downregulation of organic hydroperoxide resistance (Ohr) and DpsA proteins was observed. A downregulation of the genes encoding scavenging enzymes (katE and sodB), and gstA and trxB was observed in p2-fldX1 cells, suggesting that FldX1 prevents the antioxidant response. More than 20 membrane proteins, including porins and transporters, showed changes in expression during the growth of both strains on hydroxyphenylacetates. An increased 4-HPA degradation by recombinant strain p2-fldX1 in soil microcosms was observed. In soil, the strain overexpressing the flavodoxin FldX1 showed a lower plasmid loss, compared to WT-p2 strain, suggesting that FldX1 contributes to bacterial fitness. Overall, these results suggest that recombinant strain p2-fldX1 is an attractive bacterium for its application in bioremediation processes of aromatic compounds. CONCLUSIONS The long-chain flavodoxin FldX1 improved the capability of P. xenovorans to degrade 4-HPA in liquid culture and soil microcosms by protecting cells against the degradation-associated oxidative stress.
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Affiliation(s)
- Laura Rodríguez-Castro
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología Daniel Alkalay Lowitt, Universidad Técnica Federico Santa María, Avenida España 1680, 2390123, Valparaíso, Chile
| | - Roberto E Durán
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología Daniel Alkalay Lowitt, Universidad Técnica Federico Santa María, Avenida España 1680, 2390123, Valparaíso, Chile
- Millenium Nucleus Bioproducts, Genomics and Environmental Genomics (BioGEM), Avenida España 1680, 2390123, Valparaíso, Chile
| | - Valentina Méndez
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología Daniel Alkalay Lowitt, Universidad Técnica Federico Santa María, Avenida España 1680, 2390123, Valparaíso, Chile
- Millenium Nucleus Bioproducts, Genomics and Environmental Genomics (BioGEM), Avenida España 1680, 2390123, Valparaíso, Chile
| | - Flavia Dorochesi
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología Daniel Alkalay Lowitt, Universidad Técnica Federico Santa María, Avenida España 1680, 2390123, Valparaíso, Chile
| | - Daniela Zühlke
- Institute of Microbiology, University of Greifswald, Felix-Hausdorff-Strasse 8, 17489, Greifswald, Germany
| | - Katharina Riedel
- Institute of Microbiology, University of Greifswald, Felix-Hausdorff-Strasse 8, 17489, Greifswald, Germany
| | - Michael Seeger
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología Daniel Alkalay Lowitt, Universidad Técnica Federico Santa María, Avenida España 1680, 2390123, Valparaíso, Chile.
- Millenium Nucleus Bioproducts, Genomics and Environmental Genomics (BioGEM), Avenida España 1680, 2390123, Valparaíso, Chile.
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Khan S, Ansari A, Brachi M, Das D, El Housseini W, Minteer S, Miller AF. Structure, dynamics, and redox reactivity of an all-purpose flavodoxin. J Biol Chem 2024; 300:107122. [PMID: 38417793 PMCID: PMC10979112 DOI: 10.1016/j.jbc.2024.107122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/15/2024] [Accepted: 02/21/2024] [Indexed: 03/01/2024] Open
Abstract
The flavodoxin of Rhodopseudomonas palustris CGA009 (Rp9Fld) supplies highly reducing equivalents to crucial enzymes such as hydrogenase, especially when the organism is iron-restricted. By acquiring those electrons from photodriven electron flow via the bifurcating electron transfer flavoprotein, Rp9Fld provides solar power to vital metabolic processes. To understand Rp9Fld's ability to work with diverse partners, we solved its crystal structure. We observed the canonical flavodoxin (Fld) fold and features common to other long-chain Flds but not all the surface loops thought to recognize partner proteins. Moreover, some of the loops display alternative structures and dynamics. To advance studies of protein-protein associations and conformational consequences, we assigned the 19F NMR signals of all five tyrosines (Tyrs). Our electrochemical measurements show that incorporation of 3-19F-Tyr in place of Tyr has only a modest effect on Rp9Fld's redox properties even though Tyrs flank the flavin on both sides. Meanwhile, the 19F probes demonstrate the expected paramagnetic effect, with signals from nearby Tyrs becoming broadened beyond detection when the flavin semiquinone is formed. However, the temperature dependencies of chemical shifts and linewidths reveal dynamics affecting loops close to the flavin and regions that bind to partners in a variety of systems. These coincide with patterns of amino acid type conservation but not retention of specific residues, arguing against detailed specificity with respect to partners. We propose that the loops surrounding the flavin adopt altered conformations upon binding to partners and may even participate actively in electron transfer.
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Affiliation(s)
- Sharique Khan
- Department of Chemistry, University of Kentucky, Lexington, Kentucky, USA
| | - Ahmadullah Ansari
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Monica Brachi
- Department of Chemistry, University of Utah, Salt Lake City, Utah, USA
| | - Debarati Das
- Department of Chemistry, University of Kentucky, Lexington, Kentucky, USA
| | | | - Shelley Minteer
- Department of Chemistry, University of Utah, Salt Lake City, Utah, USA; Department of Chemistry, Kummer Institute Center for Resource Sustainability, Missouri University of Science and Technology, Rolla, Missouri, USA
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Troitzsch D, Knop R, Dittmann S, Bartel J, Zühlke D, Möller TA, Trän L, Echelmeyer T, Sievers S. Characterizing the flavodoxin landscape in Clostridioides difficile. Microbiol Spectr 2024; 12:e0189523. [PMID: 38319052 PMCID: PMC10913485 DOI: 10.1128/spectrum.01895-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 12/23/2023] [Indexed: 02/07/2024] Open
Abstract
Clostridioides difficile infections have become a major challenge in medical facilities. The bacterium is capable of spore formation allowing the survival of antibiotic treatment. Therefore, research on the physiology of C. difficile is important for the development of alternative treatment strategies. In this study, we investigated eight putative flavodoxins of C. difficile 630. Flavodoxins are small electron transfer proteins of specifically low potential. The unusually high number of flavodoxins in C. difficile suggests that they are expressed under different conditions. We determined high transcription levels for several flavodoxins during the exponential growth phase, especially for floX. Since flavodoxins are capable of replacing ferredoxins under iron deficiency conditions in other bacteria, we also examined their expression in C. difficile under low iron and no iron levels. In particular, the amount of fldX increased with decreasing iron concentration and thus could possibly replace ferredoxins. Moreover, we demonstrated that fldX is increasingly expressed under different oxidative stress conditions and thus may play an important role in the oxidative stress response. While increased fldX expression was detectable at both RNA and protein level, CD2825 showed increased expression only at mRNA level under H2O2 stress with sufficient iron availability and may indicate hydroxyl radical-dependent transcription. Although the exact function of the individual flavodoxins in C. difficile needs to be further investigated, the present study shows that flavodoxins could play an important role in several physiological processes and under infection-relevant conditions. IMPORTANCE The gram-positive, anaerobic, and spore-forming bacterium Clostridioides difficile has become a vast problem in human health care facilities. The antibiotic-associated infection with this intestinal pathogen causes serious and recurrent inflammation of the intestinal epithelium, in many cases with a severe course. To come up with novel targeted therapies against C. difficile infections, a more detailed knowledge on the pathogen's physiology is mandatory. Eight putative flavodoxins, an extraordinarily high copy number of this type of small electron transfer proteins, are annotated for C. difficile. Flavodoxins are known to be essential electron carriers in other bacteria, for instance, during infection-relevant conditions such as iron limitation and oxidative stress. This work is a first and comprehensive overview on characteristics and expression profiles of the putative flavodoxins in the pathogen C. difficile.
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Affiliation(s)
- Daniel Troitzsch
- Department of Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Robert Knop
- Department of Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Silvia Dittmann
- Department of Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Jürgen Bartel
- Department of Microbial Proteomics, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Daniela Zühlke
- Department of Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Timon Alexander Möller
- Department of Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Linda Trän
- Department of Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Thaddäus Echelmeyer
- Department of Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
| | - Susanne Sievers
- Department of Microbial Physiology and Molecular Biology, Institute of Microbiology, University of Greifswald, Greifswald, Germany
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Palavecino A, Sartorio MG, Carrillo N, Cortez N, Bortolotti A. The extremophilic Andean isolate Acinetobacter sp. Ver3 expresses two ferredoxin-NADP + reductase isoforms with different catalytic properties. FEBS Lett 2024; 598:670-683. [PMID: 38433717 DOI: 10.1002/1873-3468.14826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 01/04/2024] [Accepted: 01/06/2024] [Indexed: 03/05/2024]
Abstract
Ferredoxin/flavodoxin-NADPH reductases (FPRs) catalyze the reversible electron transfer between NADPH and ferredoxin/flavodoxin. The Acinetobacter sp. Ver3 isolated from high-altitude Andean lakes contains two isoenzymes, FPR1ver3 and FPR2ver3. Absorption spectra of these FPRs revealed typical features of flavoproteins, consistent with the use of FAD as a prosthetic group. Spectral differences indicate distinct electronic arrangements for the flavin in each enzyme. Steady-state kinetic measurements show that the enzymes display catalytic efficiencies in the order of 1-6 μm-1·s-1, although FPR1ver3 exhibited higher kcat values compared to FPR2ver3. When flavodoxinver3 was used as a substrate, both reductases exhibited dissimilar behavior. Moreover, only FPR1ver3 is induced by oxidative stimuli, indicating that the polyextremophile Ver3 has evolved diverse strategies to cope with oxidative environments.
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Affiliation(s)
- Alejandro Palavecino
- Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario (UNR & CONICET), Universidad Nacional de Rosario, Argentina
| | - Mariana Gabriela Sartorio
- Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario (UNR & CONICET), Universidad Nacional de Rosario, Argentina
| | - Néstor Carrillo
- Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario (UNR & CONICET), Universidad Nacional de Rosario, Argentina
| | - Néstor Cortez
- Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario (UNR & CONICET), Universidad Nacional de Rosario, Argentina
| | - Ana Bortolotti
- Área Biofísica, Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas., Universidad Nacional de Rosario (UNR & CONICET), Rosario, Argentina
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Beyria L, Gourbeyre O, Salillas S, Mahía A, Díaz de Villegas MD, Aínsa JA, Sancho J, Bousquet-Mélou A, Ferran AA. Antimicrobial combinations against Helicobacter pylori including benzoxadiazol-based flavodoxin inhibitors: in vitro characterization. Microbiol Spectr 2024; 12:e0262323. [PMID: 38084974 PMCID: PMC10783109 DOI: 10.1128/spectrum.02623-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 11/05/2023] [Indexed: 01/13/2024] Open
Abstract
IMPORTANCE The antimicrobial resistance of Helicobacter pylori (Hp) currently poses a threat to available treatment regimens. Developing antimicrobial drugs targeting new bacterial targets is crucial, and one such class of drugs includes Hp-flavodoxin (Hp-fld) inhibitors that target an essential metabolic pathway in Hp. Our study demonstrated that combining these new drugs with conventional antibiotics used for Hp infection treatment prevented the regrowth observed with drugs used alone. Hp-fld inhibitors show promise as new drugs to be incorporated into the treatment of Hp infection, potentially reducing the development of resistance and shortening the treatment duration.
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Affiliation(s)
- Lilha Beyria
- INTHERES, Université de Toulouse, INRAE, ENVT, Toulouse, France
| | | | - Sandra Salillas
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, University of Zaragoza, Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza, Spain
| | - Alejandro Mahía
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, University of Zaragoza, Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza, Spain
| | - María Dolores Díaz de Villegas
- CSIC—Departamento de Química Orgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), University of Zaragoza, Zaragoza, Spain
| | - José Antonio Aínsa
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza, Spain
- Departamento de Microbiología, Pediatría, Radiología y Salud Pública, Facultad de Medicina, University of Zaragoza, Zaragoza, Spain
- CIBER de Enfermedades Respiratorias–CIBERES, Instituto de Salud Carlos III, Madrid, Spain
| | - Javier Sancho
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, Zaragoza, Spain
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, University of Zaragoza, Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), Zaragoza, Spain
| | | | - Aude A. Ferran
- INTHERES, Université de Toulouse, INRAE, ENVT, Toulouse, France
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Gandra RM, Johnson CJ, Nett JE, Konopka JB. The Candida albicans ζ-crystallin homolog Zta1 promotes resistance to oxidative stress. mSphere 2023; 8:e0050723. [PMID: 38032185 PMCID: PMC10732081 DOI: 10.1128/msphere.00507-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 10/13/2023] [Indexed: 12/01/2023] Open
Abstract
IMPORTANCE Candida albicans is an important human pathogen that can cause lethal systemic infections. The ability of C. albicans to colonize and establish infections is closely tied to its highly adaptable nature and capacity to resist various types of stress, including oxidative stress. Previous studies showed that four C. albicans proteins belonging to the flavodoxin-like protein family of quinone reductases are needed for resistance to quinones and virulence. Therefore, in this study, we examined the role of a distinct type of quinone reductase, Zta1, and found that it acts in conjunction with the flavodoxin-like proteins to protect against oxidative stress.
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Affiliation(s)
- Rafael M. Gandra
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, USA
| | - Chad J. Johnson
- Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jeniel E. Nett
- Department of Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - James B. Konopka
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, USA
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Demarchi M, Arce RC, Campi M, Pierella Karlusich JJ, Hajirezaei MR, Melzer M, Lodeyro AF, Chan RL, Carrillo N. Targeting of flavodoxin to chloroplasts of mesophyll but not bundle sheath maize cells confers increased drought tolerance. New Phytol 2023; 240:2179-2184. [PMID: 37814446 DOI: 10.1111/nph.19281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 08/28/2023] [Indexed: 10/11/2023]
Affiliation(s)
- Mariana Demarchi
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
| | - Rocío C Arce
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
| | - Mabel Campi
- Instituto de Agrobiotecnología del Litoral (IAL-UNL/CONICET), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral (UNL), 3000, Santa Fe, Argentina
| | - Juan J Pierella Karlusich
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
| | - Mohammad-Reza Hajirezaei
- Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, Corrensstrasse, D-06466, Stadt Seeland, Germany
| | - Michael Melzer
- Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, Corrensstrasse, D-06466, Stadt Seeland, Germany
| | - Anabella F Lodeyro
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
| | - Raquel L Chan
- Instituto de Agrobiotecnología del Litoral (IAL-UNL/CONICET), Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral (UNL), 3000, Santa Fe, Argentina
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
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8
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Zhang Y, Yang J, Liu N, Wang L, Lu F, Chen J, Zhong D. Ultrafast Nonequilibrium Dynamics of Vibrationally Hot Electron Transfer in Flavodoxin. J Phys Chem Lett 2023; 14:10657-10663. [PMID: 38031667 DOI: 10.1021/acs.jpclett.3c02438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
The understanding of ultrafast short-range electron transfer (ET) in proteins remains challenging, and thorough studies on well-defined biological systems are demanding. Here, we utilized two types of flavodoxins and designed a series of mutants on two positions to systematically characterize the complete photoinduced redox cycles. We identified one position with a favorable orientation and distance for ultrafast ET in a few femtoseconds and the other position is relatively flexible with a longer ET time scale. We found that all forward and back ET dynamics are ultrafast nonequilibrium processes, occurring through highly vibronic states and ending in vibrationally hot ground states with subsequent cooling relaxation to efficiently dissipate photon energy into the protein environment.
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Affiliation(s)
- Yifei Zhang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jie Yang
- College of Science, Nanjing Forestry University, Nanjing 210037, China
| | - Na Liu
- Center for Ultrafast Science and Technology, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Lijuan Wang
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Faming Lu
- Center for Ultrafast Science and Technology, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jie Chen
- Center for Ultrafast Science and Technology, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dongping Zhong
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
- Department of Physics, Department of Chemistry and Biochemistry, and Program of Biophysics, Program of Chemical Physics, and Program of Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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Lewis JP, Gui Q. Iron Deficiency Modulates Metabolic Landscape of Bacteroidetes Promoting Its Resilience during Inflammation. Microbiol Spectr 2023; 11:e0473322. [PMID: 37314331 PMCID: PMC10434189 DOI: 10.1128/spectrum.04733-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 05/05/2023] [Indexed: 06/15/2023] Open
Abstract
Bacteria have to persist under low iron conditions in order to adapt to the nutritional immunity of a host. Since the knowledge of iron stimulon of Bacteroidetes is sparse, we examined oral (Porphyromonas gingivalis and Prevotella intermedia) and gut (Bacteroides thataiotaomicron) representatives for their ability to adapt to iron deplete and iron replete conditions. Our transcriptomics and comparative genomics analysis show that many iron-regulated mechanisms are conserved within the phylum. They include genes upregulated in low iron, as follows: fldA (flavodoxin), hmu (hemin uptake operon), and loci encoding ABC transporters. Downregulated genes were frd (ferredoxin), rbr (rubrerythrin), sdh (succinate dehydrogenase/fumarate reductase), vor (oxoglutarate oxidoreductase/dehydrogenase), and pfor (pyruvate:ferredoxin/flavodoxin oxidoreductase). Some genus-specific mechanisms, such as the sus of B. thetaiotaomicron coding for carbohydrate metabolism and the xusABC coding for xenosiderophore utilization were also identified. While all bacteria tested in our study had the nrfAH operon coding for nitrite reduction and were able to reduce nitrite levels present in culture media, the expression of the operon was iron dependent only in B. thetaiotaomicron. It is noteworthy that we identified a significant overlap between regulated genes found in our study and the B. thetaiotaomicron colitis study (W. Zhu, M. G. Winter, L. Spiga, E. R. Hughes et al., Cell Host Microbe 27:376-388, 2020, http://dx.doi.org/10.1016/j.chom.2020.01.010). Many of those commonly regulated genes were also iron regulated in the oral bacterial genera. Overall, this work points to iron being the master regulator enabling bacterial persistence in the host and paves the way for a more generalized investigation of the molecular mechanisms of iron homeostasis in Bacteroidetes. IMPORTANCE Bacteroidetes are an important group of anaerobic bacteria abundant both in the oral and gut microbiomes. Although iron is a required nutrient for most living organisms, the molecular mechanisms of adaptation to the changing levels of iron are not well known in this group of bacteria. We defined the iron stimulon of Bacteroidetes by examination of the transcriptomic response of Porphyromonas gingivalis and Prevotella intermedia (both belong to the oral microbiome) and Bacteroidetes thetaiotaomicron (belongs to the gut microbiome). Our results indicate that many of the iron-regulated operons are shared among the three genera. Furthermore, using bioinformatics analysis, we identified a significant overlap between our in vitro studies and transcriptomic data derived from a colitis study, thus underscoring the biological significance of our work. Defining the iron-dependent stimulon of Bacteroidetes can help to identify the molecular mechanisms of iron-dependent regulation as well as better understand the persistence of the anaerobes in the human host.
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Affiliation(s)
- Janina P. Lewis
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA
- Department of Biochemistry, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Qin Gui
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA
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10
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McGregor AK, Chan ACK, Schroeder MD, Do LTM, Saini G, Murphy MEP, Wolthers KR. A new member of the flavodoxin superfamily from Fusobacterium nucleatum that functions in heme trafficking and reduction of anaerobilin. J Biol Chem 2023; 299:104902. [PMID: 37302554 PMCID: PMC10404700 DOI: 10.1016/j.jbc.2023.104902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 05/18/2023] [Accepted: 05/24/2023] [Indexed: 06/13/2023] Open
Abstract
Fusobacterium nucleatum is an opportunistic oral pathogen that is associated with various cancers. To fulfill its essential need for iron, this anaerobe will express heme uptake machinery encoded at a single genetic locus. The heme uptake operon includes HmuW, a class C radical SAM-dependent methyltransferase that degrades heme anaerobically to release Fe2+ and a linear tetrapyrrole called anaerobilin. The last gene in the operon, hmuF encodes a member of the flavodoxin superfamily of proteins. We discovered that HmuF and a paralog, FldH, bind tightly to both FMN and heme. The structure of Fe3+-heme-bound FldH (1.6 Å resolution) reveals a helical cap domain appended to the ⍺/β core of the flavodoxin fold. The cap creates a hydrophobic binding cleft that positions the heme planar to the si-face of the FMN isoalloxazine ring. The ferric heme iron is hexacoordinated to His134 and a solvent molecule. In contrast to flavodoxins, FldH and HmuF do not stabilize the FMN semiquinone but instead cycle between the FMN oxidized and hydroquinone states. We show that heme-loaded HmuF and heme-loaded FldH traffic heme to HmuW for degradation of the protoporphyrin ring. Both FldH and HmuF then catalyze multiple reductions of anaerobilin through hydride transfer from the FMN hydroquinone. The latter activity eliminates the aromaticity of anaerobilin and the electrophilic methylene group that was installed through HmuW turnover. Hence, HmuF provides a protected path for anaerobic heme catabolism, offering F. nucleatum a competitive advantage in the colonization of anoxic sites of the human body.
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Affiliation(s)
| | - Anson C K Chan
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Megan D Schroeder
- Department of Chemistry, University of British Columbia, Kelowna, Canada
| | - Long T M Do
- Department of Chemistry, University of British Columbia, Kelowna, Canada
| | - Gurpreet Saini
- Department of Chemistry, University of British Columbia, Kelowna, Canada
| | - Michael E P Murphy
- Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Kirsten R Wolthers
- Department of Chemistry, University of British Columbia, Kelowna, Canada.
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11
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Lamb DC, Goldstone JV, Zhao B, Lei L, Mullins JGL, Allen MJ, Kelly SL, Stegeman JJ. Characterization of a Virally Encoded Flavodoxin That Can Drive Bacterial Cytochrome P450 Monooxygenase Activity. Biomolecules 2022; 12:1107. [PMID: 36009001 PMCID: PMC9405906 DOI: 10.3390/biom12081107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 07/28/2022] [Accepted: 08/04/2022] [Indexed: 11/16/2022] Open
Abstract
Flavodoxins are small electron transport proteins that are involved in a myriad of photosynthetic and non-photosynthetic metabolic pathways in Bacteria (including cyanobacteria), Archaea and some algae. The sequenced genome of 0305φ8-36, a large bacteriophage that infects the soil bacterium Bacillus thuringiensis, was predicted to encode a putative flavodoxin redox protein. Here we confirm that 0305φ8-36 phage encodes a FMN-containing flavodoxin polypeptide and we report the expression, purification and enzymatic characterization of the recombinant protein. Purified 0305φ8-36 flavodoxin has near-identical spectral properties to control, purified Escherichia coli flavodoxin. Using in vitro assays we show that 0305φ8-36 flavodoxin can be reconstituted with E. coli flavodoxin reductase and support regio- and stereospecific cytochrome P450 CYP170A1 allyl-oxidation of epi-isozizaene to the sesquiterpene antibiotic product albaflavenone, found in the soil bacterium Streptomyces coelicolor. In vivo, 0305φ8-36 flavodoxin is predicted to mediate the 2-electron reduction of the β subunit of phage-encoded ribonucleotide reductase to catalyse the conversion of ribonucleotides to deoxyribonucleotides during viral replication. Our results demonstrate that this phage flavodoxin has the potential to manipulate and drive bacterial P450 cellular metabolism, which may affect both the host biological fitness and the communal microbiome. Such a scenario may also be applicable in other viral-host symbiotic/parasitic relationships.
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Affiliation(s)
- David C. Lamb
- Faculty of Medicine, Health and Life Sciences, Swansea University, Swansea SA2 8PP, UK
| | - Jared V. Goldstone
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543-1050, USA
| | - Bin Zhao
- Cleveland Clinic Lerner Research Institute, 9500 Euclid Avenue, NB21, Cleveland, OH 44195, USA
| | - Li Lei
- Department of Biochemistry, Vanderbilt University Medical School, Vanderbilt University, Nashville, TN 37232-0146, USA
| | | | - Michael J. Allen
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Steven L. Kelly
- Faculty of Medicine, Health and Life Sciences, Swansea University, Swansea SA2 8PP, UK
| | - John J. Stegeman
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543-1050, USA
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12
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Shahbazi M, Tohidfar M, Aliniaeifard S, Yazdanpanah F, Bosacchi M. Transgenic tobacco co-expressing flavodoxin and betaine aldehyde dehydrogenase confers cadmium tolerance through boosting antioxidant capacity. Protoplasma 2022; 259:965-979. [PMID: 34686944 DOI: 10.1007/s00709-021-01714-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 09/29/2021] [Indexed: 06/13/2023]
Abstract
Excessive heavy metal (HM) levels in soil have become a source of concern due to their adverse effects on human health and the agriculture industry. Soil contamination by HMs leads to an accumulation of reactive oxygen species (ROSs) within the plant cell and disruption of photosynthesis-related proteins. The response of tobacco lines overexpressing flavodoxin (Fld) and betaine aldehyde dehydrogenase (BADH) to cadmium (Cd) toxicity was investigated in this study. PCR results demonstrated the expected amplicon length of each gene in the transgenic lines. Absolute qRT-PCR demonstrates a single copy of T-DNA integration into each transgenic line. Relative qRT-PCR confirmed overexpression of Fld and BADH in transgenic lines. The maximum quantum yield of photosystem II (Fv/Fm) was measured under Cd toxicity stress and revealed that transgenic lines had a higher Fv/Fm than wild-type (WT) plants. Accumulation of proline, glycine betaine (GB), and higher activity of antioxidant enzymes alongside lower levels of malondialdehyde (MDA) and hydrogen peroxide (H2O2) was indicative of a robust antioxidant system in transgenic plants. Therefore, performing a loop in reducing the ROS produced in the photosynthesis electron transport chain and stimulating the ROS scavenger enzyme activity improved the plant tolerance to Cd stress.
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Affiliation(s)
- Mehrdad Shahbazi
- Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, 1983969411, Tehran, Iran
| | - Masoud Tohidfar
- Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, 1983969411, Tehran, Iran.
| | - Sasan Aliniaeifard
- Photosynthesis Laboratory, Department of Horticulture, Aburaihan Campus, University of Tehran, 1417935840, Tehran, Iran
| | - Farzaneh Yazdanpanah
- Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, 1983969411, Tehran, Iran
| | - Massimo Bosacchi
- Park at the, Danforth Plant Science Center, KWS Gateway Research Center, LLC, BRDG, Saint Louis, MO, USA
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13
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Abstract
Short-range protein electron transfer (ET) is crucially important in light-induced biological processes such as in photoenzymes and photoreceptors and often occurs on time scales similar to those of environment fluctuations, leading to a coupled dynamic process. Herein, we use semiquinone Anabaena flavodoxin to characterize the ultrafast photoinduced redox cycle of the wild type and seven mutants by ultrafast spectroscopy. We have found that the forward and backward ET dynamics show stretched behaviors in a few picoseconds (1-5 ps), indicating a coupling with the local protein fluctuations. By comparison with the results from semiquinone D. vulgaris flavodoxin, we find that the electronic coupling is crucial to the ET rates. With our new nonergodic model, we obtain smaller values of the outer reorganization energy (λoγ) of environment fluctuations and the reaction free energy force (ΔGγ), a signature of nonequilibrium ET dynamics.
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Affiliation(s)
- Jie Yang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yifei Zhang
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yangyi Lu
- Department of Physics, Department of Chemistry and Biochemistry, Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Lijuan Wang
- Department of Physics, Department of Chemistry and Biochemistry, Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Faming Lu
- Center for Ultrafast Science and Technology, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Dongping Zhong
- Center for Ultrafast Science and Technology, School of Chemistry and Chemical Engineering, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Department of Physics, Department of Chemistry and Biochemistry, Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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14
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Yi J, Huang H, Liang J, Wang R, Liu Z, Li F, Wang S. A Heterodimeric Reduced-Ferredoxin-Dependent Methylenetetrahydrofolate Reductase from Syngas-Fermenting Clostridium ljungdahlii. Microbiol Spectr 2021; 9:e0095821. [PMID: 34643446 PMCID: PMC8515935 DOI: 10.1128/spectrum.00958-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Accepted: 08/31/2021] [Indexed: 11/20/2022] Open
Abstract
The strict anaerobe Clostridium ljungdahlii can ferment CO or H2/CO2 via the Wood-Ljungdahl pathway to acetate, ethanol, and 2,3-butanediol. This ability has attracted considerable interest, since it can be used for syngas fermentation to produce biofuels and biochemicals. However, the key enzyme methylenetetrahydrofolate reductase (MTHFR) in the Wood-Ljungdahl pathway of the strain has not been characterized, and its physiological electron donor is unclear. In this study, we purified the enzyme 46-fold with a benzyl viologen reduction activity of 41.2 U/mg from C. ljungdahlii cells grown on CO. It is composed of two subunits, MetF (31.5 kDa) and MetV (23.5 kDa), and has an apparent molecular mass of 62.2 kDa. The brownish yellow protein contains 0.73 flavin mononucleotide (FMN) and 7.4 Fe, in agreement with the prediction that MetF binds one flavin and MetV binds two [4Fe4S] clusters. It cannot use NAD(P)H as its electron donor or catalyze an electron-bifurcating reaction in combination with ferredoxin as an electron acceptor. The reduced recombinant ferredoxin, flavodoxin, and thioredoxin of C. ljungdahlii can serve as electron donors with specific activities of 91.2, 22.1, and 7.4 U/mg, respectively. The apparent Km values for reduced ferredoxin and flavodoxin were around 1.46 μM and 0.73 μM, respectively. Subunit composition and phylogenetic analysis showed that the enzyme from C. ljungdahlii belongs to MetFV-type MTHFR, which is a heterodimer, and uses reduced ferredoxin as its electron donor. Based on these results, we discuss the energy metabolism of C. ljungdahlii when it grows on CO or H2 plus CO2. IMPORTANCE Syngas, a mixture of CO, CO2, and H2, is the main component of steel mill waste gas and also can be generated by the gasification of biomass and urban domestic waste. Its fermentation to biofuels and biocommodities has attracted attention due to the economic and environmental benefits of this process. Clostridium ljungdahlii is one of the superior acetogens used in the technology. However, the biochemical mechanism of its gas fermentation via the Wood-Ljungdahl pathway is not completely clear. In this study, the key enzyme, methylenetetrahydrofolate reductase (MTHFR), was characterized and found to be a non-electron-bifurcating heterodimer with reduced ferredoxin as its electron donor, representing another example of MetFV-type MTHFR. The findings will form the basis for a deeper understanding of the energy metabolism of syngas fermentation by C. ljungdahlii, which is valuable for developing metabolic engineering strains and efficient syngas fermentation technologies.
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Affiliation(s)
- Jihong Yi
- State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao, People’s Republic of China
| | - Haiyan Huang
- School of Basic Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, People’s Republic of China
| | - Jiyu Liang
- State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao, People’s Republic of China
| | - Rufei Wang
- State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao, People’s Republic of China
| | - Ziyong Liu
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, People’s Republic of China
| | - Fuli Li
- Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, People’s Republic of China
| | - Shuning Wang
- State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao, People’s Republic of China
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15
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Salillas S, Galano-Frutos JJ, Mahía A, Maity R, Conde-Giménez M, Anoz-Carbonell E, Berlamont H, Velazquez-Campoy A, Touati E, Mamat U, Schaible UE, Gálvez JA, Díaz-de-Villegas MD, Haesebrouck F, Aínsa JA, Sancho J. Selective Targeting of Human and Animal Pathogens of the Helicobacter Genus by Flavodoxin Inhibitors: Efficacy, Synergy, Resistance and Mechanistic Studies. Int J Mol Sci 2021; 22:ijms221810137. [PMID: 34576300 PMCID: PMC8467567 DOI: 10.3390/ijms221810137] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 02/08/2023] Open
Abstract
Antimicrobial resistant (AMR) bacteria constitute a global health concern. Helicobacter pylori is a Gram-negative bacterium that infects about half of the human population and is a major cause of peptic ulcer disease and gastric cancer. Increasing resistance to triple and quadruple H. pylori eradication therapies poses great challenges and urges the development of novel, ideally narrow spectrum, antimicrobials targeting H. pylori. Here, we describe the antimicrobial spectrum of a family of nitrobenzoxadiazol-based antimicrobials initially discovered as inhibitors of flavodoxin: an essential H. pylori protein. Two groups of inhibitors are described. One group is formed by narrow-spectrum compounds, highly specific for H. pylori, but ineffective against enterohepatic Helicobacter species and other Gram-negative or Gram-positive bacteria. The second group includes extended-spectrum antimicrobials additionally targeting Gram-positive bacteria, the Gram-negative Campylobacter jejuni, and most Helicobacter species, but not affecting other Gram-negative pathogens. To identify the binding site of the inhibitors in the flavodoxin structure, several H. pylori-flavodoxin variants have been engineered and tested using isothermal titration calorimetry. An initial study of the inhibitors capacity to generate resistances and of their synergism with antimicrobials commonly used in H. pylori eradication therapies is described. The narrow-spectrum inhibitors, which are expected to affect the microbiota less dramatically than current antimicrobial drugs, offer an opportunity to develop new and specific H. pylori eradication combinations to deal with AMR in H. pylori. On the other hand, the extended-spectrum inhibitors constitute a new family of promising antimicrobials, with a potential use against AMR Gram-positive bacterial pathogens.
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Affiliation(s)
- Sandra Salillas
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, 50018 Zaragoza, Spain; (S.S.); (J.J.G.-F.); (A.M.); (R.M.); (M.C.-G.); (E.A.-C.); (A.V.-C.); (J.A.A.)
- Departamento de Bioquímica y Biología Molecular y Celular, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
| | - Juan José Galano-Frutos
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, 50018 Zaragoza, Spain; (S.S.); (J.J.G.-F.); (A.M.); (R.M.); (M.C.-G.); (E.A.-C.); (A.V.-C.); (J.A.A.)
- Departamento de Bioquímica y Biología Molecular y Celular, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
| | - Alejandro Mahía
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, 50018 Zaragoza, Spain; (S.S.); (J.J.G.-F.); (A.M.); (R.M.); (M.C.-G.); (E.A.-C.); (A.V.-C.); (J.A.A.)
- Departamento de Bioquímica y Biología Molecular y Celular, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
| | - Ritwik Maity
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, 50018 Zaragoza, Spain; (S.S.); (J.J.G.-F.); (A.M.); (R.M.); (M.C.-G.); (E.A.-C.); (A.V.-C.); (J.A.A.)
- Departamento de Bioquímica y Biología Molecular y Celular, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
| | - María Conde-Giménez
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, 50018 Zaragoza, Spain; (S.S.); (J.J.G.-F.); (A.M.); (R.M.); (M.C.-G.); (E.A.-C.); (A.V.-C.); (J.A.A.)
- Departamento de Bioquímica y Biología Molecular y Celular, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
| | - Ernesto Anoz-Carbonell
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, 50018 Zaragoza, Spain; (S.S.); (J.J.G.-F.); (A.M.); (R.M.); (M.C.-G.); (E.A.-C.); (A.V.-C.); (J.A.A.)
- Departamento de Bioquímica y Biología Molecular y Celular, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain
- Departamento de Microbiología, Pediatría, Radiología y Salud Pública, Faculty of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
| | - Helena Berlamont
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B9820 Merelbeke, Belgium; (H.B.); (F.H.)
| | - Adrian Velazquez-Campoy
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, 50018 Zaragoza, Spain; (S.S.); (J.J.G.-F.); (A.M.); (R.M.); (M.C.-G.); (E.A.-C.); (A.V.-C.); (J.A.A.)
- Departamento de Bioquímica y Biología Molecular y Celular, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
- ARAID Foundation, Government of Aragon, 50018 Zaragoza, Spain
- CIBER de Enfermedades Hepáticas y Digestivas CIBERehd, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Eliette Touati
- Unit of Helicobacter Pathogenesis, CNRS UMR2001, Department of Microbiology, Institut Pasteur, 25-28 Rue du Dr. Roux, 75724 Paris, France;
| | - Uwe Mamat
- Cellular Microbiology, Program Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany; (U.M.); (U.E.S.)
| | - Ulrich E. Schaible
- Cellular Microbiology, Program Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany; (U.M.); (U.E.S.)
| | - José A. Gálvez
- Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC—Departamento de Química Orgánica, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain; (J.A.G.); (M.D.D.-d.-V.)
| | - María D. Díaz-de-Villegas
- Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC—Departamento de Química Orgánica, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain; (J.A.G.); (M.D.D.-d.-V.)
| | - Freddy Haesebrouck
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B9820 Merelbeke, Belgium; (H.B.); (F.H.)
| | - José A. Aínsa
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, 50018 Zaragoza, Spain; (S.S.); (J.J.G.-F.); (A.M.); (R.M.); (M.C.-G.); (E.A.-C.); (A.V.-C.); (J.A.A.)
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
- Departamento de Microbiología, Pediatría, Radiología y Salud Pública, Faculty of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
- CIBER de Enfermedades Respiratorias—CIBERES, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Javier Sancho
- Biocomputation and Complex Systems Physics Institute (BIFI)-Joint Units: BIFI-IQFR (CSIC) and GBsC-CSIC, University of Zaragoza, 50018 Zaragoza, Spain; (S.S.); (J.J.G.-F.); (A.M.); (R.M.); (M.C.-G.); (E.A.-C.); (A.V.-C.); (J.A.A.)
- Departamento de Bioquímica y Biología Molecular y Celular, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), 50009 Zaragoza, Spain
- Correspondence:
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16
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Kayastha K, Vitt S, Buckel W, Ermler U. Flavins in the electron bifurcation process. Arch Biochem Biophys 2021; 701:108796. [PMID: 33609536 DOI: 10.1016/j.abb.2021.108796] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 02/01/2021] [Accepted: 02/03/2021] [Indexed: 11/18/2022]
Abstract
The discovery of a new energy-coupling mechanism termed flavin-based electron bifurcation (FBEB) in 2008 revealed a novel field of application for flavins in biology. The key component is the bifurcating flavin endowed with strongly inverted one-electron reduction potentials (FAD/FAD•- ≪ FAD•-/FADH-) that cooperatively transfers in its reduced state one low and one high-energy electron into different directions and thereby drives an endergonic with an exergonic reduction reaction. As energy splitting at the bifurcating flavin apparently implicates one-electron chemistry, the FBEB machinery has to incorporate prior to and behind the central bifurcating flavin 2e-to-1e and 1e-to-2e switches, frequently also flavins, for oxidizing variable medium-potential two-electron donating substrates and for reducing high-potential two-electron accepting substrates. The one-electron carriers ferredoxin or flavodoxin serve as low-potential (high-energy) electron acceptors, which power endergonic processes almost exclusively in obligate anaerobic microorganisms to increase the efficiency of their energy metabolism. In this review, we outline the global organization of FBEB enzymes, the functions of the flavins therein and the surrounding of the isoalloxazine rings by which their reduction potentials are specifically adjusted in a finely tuned energy landscape.
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Affiliation(s)
- Kanwal Kayastha
- Max-Planck-Institut für Biophysik, Max-von-Laue-Str. 3, 60438, Frankfurt am Main, Germany
| | - Stella Vitt
- Max-Planck-Institut für Biophysik, Max-von-Laue-Str. 3, 60438, Frankfurt am Main, Germany; Laboratorium für Mikrobiologie, Fachbereich Biologie and SYNMIKRO, Philipps-Universität, 35032, Marburg, Germany
| | - Wolfgang Buckel
- Laboratorium für Mikrobiologie, Fachbereich Biologie and SYNMIKRO, Philipps-Universität, 35032, Marburg, Germany; Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Str. 10, 35043, Marburg, Germany
| | - Ulrich Ermler
- Max-Planck-Institut für Biophysik, Max-von-Laue-Str. 3, 60438, Frankfurt am Main, Germany.
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17
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Mitra R, Gadkari VV, Meinen BA, van Mierlo CPM, Ruotolo BT, Bardwell JCA. Mechanism of the small ATP-independent chaperone Spy is substrate specific. Nat Commun 2021; 12:851. [PMID: 33558474 PMCID: PMC7870927 DOI: 10.1038/s41467-021-21120-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 01/08/2021] [Indexed: 11/17/2022] Open
Abstract
ATP-independent chaperones are usually considered to be holdases that rapidly bind to non-native states of substrate proteins and prevent their aggregation. These chaperones are thought to release their substrate proteins prior to their folding. Spy is an ATP-independent chaperone that acts as an aggregation inhibiting holdase but does so by allowing its substrate proteins to fold while they remain continuously chaperone bound, thus acting as a foldase as well. The attributes that allow such dual chaperoning behavior are unclear. Here, we used the topologically complex protein apoflavodoxin to show that the outcome of Spy's action is substrate specific and depends on its relative affinity for different folding states. Tighter binding of Spy to partially unfolded states of apoflavodoxin limits the possibility of folding while bound, converting Spy to a holdase chaperone. Our results highlight the central role of the substrate in determining the mechanism of chaperone action.
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Affiliation(s)
- Rishav Mitra
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Varun V Gadkari
- Department of Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Ben A Meinen
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | | | | | - James C A Bardwell
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA.
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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18
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Johnson WA, Redding KE. Reconstitution of the heliobacterial photochemical reaction center and cytochrome c 553 into a proteoliposome system. Photosynth Res 2020; 143:241-250. [PMID: 31838634 DOI: 10.1007/s11120-019-00695-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 11/22/2019] [Indexed: 06/10/2023]
Abstract
The heliobacterial reaction center (HbRC) is the simplest known photochemical reaction center, in terms of its polypeptide composition. In the heliobacterial cells, its electron donor is a cytochrome (cyt) c553 attached to the membrane via a covalent linkage with a diacylglycerol. We have reconstituted purified HbRC into liposomes mimicking the phospholipid composition of heliobacterial membranes. We also incorporated a lipid with a headgroup containing Ni(II):nitrilotriacetate (NTA) to provide a binding site for the soluble version of the heliobacterial cyt c553 in which the N-terminal membrane attachment site is replaced by a hexahistidine tag. The HbRC was inserted into the liposomes with the donor side preferentially exposed to the exterior; this bias increased to nearly 100% with higher concentrations (≥ 10 mol%) of the Ni(II)-NTA lipid in the membrane, and is most likely due to the net negative charge of the surface of the membrane. The HbRC in proteoliposomes without the Ni(II)-NTA lipid exhibited normal charge separation and subsequent charge recombination of the P800+FX- state in 15 ms; however, the oxidized primary donor (P800+) was not significantly reduced by added H6-cyt c553. In contrast, with proteoliposomes containing the Ni(II)-NTA lipid, addition of H6-cyt c553 resulted in a new kinetic component resulting from fast reduction (2-5 ms) of P800+ by H6-cyt c553. The contribution of this kinetic component varied with the concentration of added H6-cyt c553 and could represent 80% or more of the total P800+ decay. Thus, the HbRC and its interaction with its native electron donor have been reconstituted into an artificial membrane system.
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Affiliation(s)
- William A Johnson
- School of Molecular Sciences, Arizona State University, 1711 S Rural Rd, Box 871604, Tempe, AZ, 85287-1604, USA
| | - Kevin E Redding
- School of Molecular Sciences, Arizona State University, 1711 S Rural Rd, Box 871604, Tempe, AZ, 85287-1604, USA.
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19
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Cao P, Cao D, Si L, Su X, Tian L, Chang W, Liu Z, Zhang X, Li M. Structural basis for energy and electron transfer of the photosystem I-IsiA-flavodoxin supercomplex. Nat Plants 2020; 6:167-176. [PMID: 32042157 DOI: 10.1038/s41477-020-0593-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 01/06/2020] [Indexed: 05/10/2023]
Abstract
Under iron-deficiency stress, which occurs frequently in natural aquatic environments, cyanobacteria reduce the amount of iron-enriched proteins, including photosystem I (PSI) and ferredoxin (Fd), and upregulate the expression of iron-stress-induced proteins A and B (IsiA and flavodoxin (Fld)). Multiple IsiAs function as the peripheral antennae that encircle the PSI core, whereas Fld replaces Fd as the electron receptor of PSI. Here, we report the structures of the PSI3-IsiA18-Fld3 and PSI3-IsiA18 supercomplexes from Synechococcus sp. PCC 7942, revealing features that are different from the previously reported PSI structures, and a sophisticated pigment network that involves previously unobserved pigment molecules. Spectroscopic results demonstrated that IsiAs are efficient light harvesters for PSI. Three Flds bind symmetrically to the trimeric PSI core-we reveal the detailed interaction and the electron transport path between PSI and Fld. Our results provide a structural basis for understanding the mechanisms of light harvesting, energy transfer and electron transport of cyanobacterial PSI under stressed conditions.
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Affiliation(s)
- Peng Cao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
| | - Duanfang Cao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
| | - Long Si
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
- University of Chinese Academy of Sciences, Beijing, P. R. China
| | - Xiaodong Su
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
| | - Lijin Tian
- Institute of Botany, Chinese Academy of Sciences, Beijing, P. R. China
| | - Wenrui Chang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
- University of Chinese Academy of Sciences, Beijing, P. R. China
| | - Zhenfeng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China
- University of Chinese Academy of Sciences, Beijing, P. R. China
| | - Xinzheng Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China.
- University of Chinese Academy of Sciences, Beijing, P. R. China.
- Center for Biological Imaging, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China.
| | - Mei Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, P. R. China.
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20
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Bertsova YV, Kulik LV, Mamedov MD, Baykov AA, Bogachev AV. Flavodoxin with an air-stable flavin semiquinone in a green sulfur bacterium. Photosynth Res 2019; 142:127-136. [PMID: 31302833 DOI: 10.1007/s11120-019-00658-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 07/04/2019] [Indexed: 06/10/2023]
Abstract
Flavodoxins are small proteins with a non-covalently bound FMN that can accept two electrons and accordingly adopt three redox states: oxidized (quinone), one-electron reduced (semiquinone), and two-electron reduced (quinol). In iron-deficient cyanobacteria and algae, flavodoxin can substitute for ferredoxin as the electron carrier in the photosynthetic electron transport chain. Here, we demonstrate a similar function for flavodoxin from the green sulfur bacterium Chlorobium phaeovibrioides (cp-Fld). The expression of the cp-Fld gene, found in a close proximity with the genes for other proteins associated with iron transport and storage, increased in a low-iron medium. cp-Fld produced in Escherichia coli exhibited the optical, ERP, and electron-nuclear double resonance spectra that were similar to those of known flavodoxins. However, unlike all other flavodoxins, cp-Fld exhibited unprecedented stability of FMN semiquinone to oxidation by air and difference in midpoint redox potentials for the quinone-semiquinone and semiquinone-quinol couples (- 110 and - 530 mV, respectively). cp-Fld could be reduced by pyruvate:ferredoxin oxidoreductase found in the membrane-free extract of Chl. phaeovibrioides cells and photo-reduced by the photosynthetic reaction center found in membrane vesicles from these cells. The green sulfur bacterium Chl. phaeovibrioides appears thus to be a new type of the photosynthetic organisms that can use flavodoxin as an alternative electron carrier to cope with iron deficiency.
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Affiliation(s)
- Yulia V Bertsova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia, 119234
| | - Leonid V Kulik
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk, Russia, 630090
- Novosibirsk State University, Novosibirsk, Russia, 630090
| | - Mahir D Mamedov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia, 119234
| | - Alexander A Baykov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia, 119234
| | - Alexander V Bogachev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia, 119234.
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21
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Rodríguez-Castro L, Méndez V, Durán RE, Seeger M. Long-chain flavodoxin FldX1 improves Paraburkholderia xenovorans LB400 tolerance to oxidative stress caused by paraquat and H2O2. PLoS One 2019; 14:e0221881. [PMID: 31469877 PMCID: PMC6716667 DOI: 10.1371/journal.pone.0221881] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 08/17/2019] [Indexed: 11/26/2022] Open
Abstract
Flavodoxins are small electron transfer proteins containing flavin mononucleotide (FMN) as a prosthetic group, which play an important role during oxidative stress or iron limitation. The aims of this study were the identification and characterization of flavodoxins in the model aromatic-degrader Paraburkholderia xenovorans LB400 and the analyses of their protective effects during oxidative stress induced by paraquat and H2O2. Two genes (BxeA0278 and BxeB0391) encoding flavodoxins (hereafter referred to as fldX for flavodoxin from P. xenovorans), were identified at the LB400 major and minor chromosome. Genomic context of the flavodoxin-encoding genes showed genes encoding membrane proteins, transporters, and proteins involved in redox processes and biosynthesis of macromolecules. A secondary structure prediction of both LB400 flavodoxins showed the characteristic flavodoxin structure of five ß-sheets intercalated with five α-helices. FldX1 contains a loop intercalated in the fifth β-strand, which indicates that it belongs to the long-chain flavodoxins, whereas FldX2 is a short-chain flavodoxin. A phylogenetic analysis of 73 flavodoxins from 43 bacterial genera revealed eight clusters (I-VIII), while FldX1 and FldX2 grouped separately within a long-chain and a short-chain flavodoxin clades. FldX1 and FldX2 were overexpressed in P. xenovorans. Interestingly, the strain overexpressing the long-chain flavodoxin FldX1 (p2-fldX1) showed a faster growth in glucose than the control strain. The recombinant strain overexpressing the long-chain flavodoxin FldX1 (p2-fldx1) exposed to paraquat (20 mM) possessed lower susceptibility to growth inhibition on plates and higher survival in liquid medium than the control strain. The strains overexpressing the flavodoxins FldX1 and FldX2 showed higher survival during exposure to 1 mM paraquat (>95%) than the control strain (68%). Compared to the control strain, strains overexpressing FldX1 and FldX2 showed lower lipid peroxidation (>20%) after exposure to 1 mM paraquat and a lower protein carbonylation (~30%) after exposure to 1 mM H2O2 was observed. During exposure to paraquat, strain p2-fldx1 downregulated the katG4, hpf, trxB1 and ohr genes (> 2-fold), whereas strain p2-fldx2 upregulated the oxyR and ahpC1 genes (> 2-fold). In conclusion, the flavodoxins FldX1 and FldX2 of P. xenovorans LB400 conferred protection to cells exposed to the oxidizing agents paraquat and H2O2.
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Affiliation(s)
- Laura Rodríguez-Castro
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Valentina Méndez
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Roberto E. Durán
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Michael Seeger
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química & Centro de Biotecnología, Universidad Técnica Federico Santa María, Valparaíso, Chile
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22
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Pérez AA, Ferlez BH, Applegate AM, Walters K, He Z, Shen G, Golbeck JH, Bryant DA. Presence of a [3Fe-4S] cluster in a PsaC variant as a functional component of the photosystem I electron transfer chain in Synechococcus sp. PCC 7002. Photosynth Res 2018; 136:31-48. [PMID: 28916964 DOI: 10.1007/s11120-017-0437-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/23/2017] [Indexed: 06/07/2023]
Abstract
A site-directed C14G mutation was introduced into the stromal PsaC subunit of Synechococcus sp. strain PCC 7002 in vivo in order to introduce an exchangeable coordination site into the terminal FB [4Fe-4S] cluster of Photosystem I (PSI). Using an engineered PSI-less strain (psaAB deletion), psaC was deleted and replaced with recombinant versions controlled by a strong promoter, and the psaAB deletion was complemented. Modified PSI accumulated at lower levels in this strain and supported slower photoautotrophic growth than wild type. As-isolated PSI complexes containing PsaCC14G showed resonances with g values of 2.038 and 2.007 characteristic of a [3Fe-4S]1+ cluster. When the PSI complexes were illuminated at 15 K, these resonances partially disappeared and two new sets of resonances appeared. The majority set had g values of 2.05, 1.95, and 1.85, characteristic of FA-, and the minority set had g values of 2.11, 1.90, and 1.88 from FB' in the modified site. The S = 1/2 spin state of the latter implied the presence of a thiolate as the terminal ligand. The [3Fe-4S] clusters could be partially reconstituted with iron, producing a larger population of [4Fe-4S] clusters. Rates of flavodoxin reduction were identical in PSI complexes isolated from wild type and the PsaCC14G variant strain; this implied equivalent capacity for forward electron transfer in PSI complexes that contained [3Fe-4S] and [4Fe-4S] clusters. The development of this cyanobacterial strain is a first step toward translation of in vitro PSI-based biosolar molecular wire systems in vivo and provides new insights into the formation of Fe/S clusters.
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Affiliation(s)
- Adam A Pérez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY, 40202, USA
| | - Bryan H Ferlez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 28824, USA
| | - Amanda M Applegate
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
- Musculoskeletal Transplant Foundation, Jessup, PA, 18434, USA
| | - Karim Walters
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Zhihui He
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Gaozhong Shen
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA.
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA.
| | - Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA.
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA.
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23
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Pierella Karlusich JJ, Carrillo N. Evolution of the acceptor side of photosystem I: ferredoxin, flavodoxin, and ferredoxin-NADP + oxidoreductase. Photosynth Res 2017; 134:235-250. [PMID: 28150152 DOI: 10.1007/s11120-017-0338-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 01/12/2017] [Indexed: 05/21/2023]
Abstract
The development of oxygenic photosynthesis by primordial cyanobacteria ~2.7 billion years ago led to major changes in the components and organization of photosynthetic electron transport to cope with the challenges of an oxygen-enriched atmosphere. We review herein, following the seminal contributions as reported by Jaganathan et al. (Functional genomics and evolution of photosynthetic systems, vol 33, advances in photosynthesis and respiration, Springer, Dordrecht, 2012), how these changes affected carriers and enzymes at the acceptor side of photosystem I (PSI): the electron shuttle ferredoxin (Fd), its isofunctional counterpart flavodoxin (Fld), their redox partner ferredoxin-NADP+ reductase (FNR), and the primary PSI acceptors F x and F A/F B. Protection of the [4Fe-4S] centers of these proteins from oxidative damage was achieved by strengthening binding between the F A/F B polypeptide and the reaction center core containing F x, therefore impairing O2 access to the clusters. Immobilization of F A/F B in the PSI complex led in turn to the recruitment of new soluble electron shuttles. This function was fulfilled by oxygen-insensitive [2Fe-2S] Fd, in which the reactive sulfide atoms of the cluster are shielded from solvent by the polypeptide backbone, and in some algae and cyanobacteria by Fld, which employs a flavin as prosthetic group and is tolerant to oxidants and iron limitation. Tight membrane binding of FNR allowed solid-state electron transfer from PSI bridged by Fd/Fld. Fine tuning of FNR catalytic mechanism led to formidable increases in turnover rates compared with FNRs acting in heterotrophic pathways, favoring Fd/Fld reduction instead of oxygen reduction.
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Affiliation(s)
- Juan José Pierella Karlusich
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Ocampo y Esmeralda, 2000, Rosario, Argentina
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), Ocampo y Esmeralda, 2000, Rosario, Argentina.
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24
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Li Z, Yuan S, Jia H, Gao F, Zhou M, Yuan N, Wu P, Hu Q, Sun D, Luo H. Ectopic expression of a cyanobacterial flavodoxin in creeping bentgrass impacts plant development and confers broad abiotic stress tolerance. Plant Biotechnol J 2017; 15:433-446. [PMID: 27638479 PMCID: PMC5362689 DOI: 10.1111/pbi.12638] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/10/2016] [Accepted: 09/13/2016] [Indexed: 05/18/2023]
Abstract
Flavodoxin (Fld) plays a pivotal role in photosynthetic microorganisms as an alternative electron carrier flavoprotein under adverse environmental conditions. Cyanobacterial Fld has been demonstrated to be able to substitute ferredoxin of higher plants in most electron transfer processes under stressful conditions. We have explored the potential of Fld for use in improving plant stress response in creeping bentgrass (Agrostis stolonifera L.). Overexpression of Fld altered plant growth and development. Most significantly, transgenic plants exhibited drastically enhanced performance under oxidative, drought and heat stress as well as nitrogen (N) starvation, which was associated with higher water retention and cell membrane integrity than wild-type controls, modified expression of heat-shock protein genes, production of more reduced thioredoxin, elevated N accumulation and total chlorophyll content as well as up-regulated expression of nitrite reductase and N transporter genes. Further analysis revealed that the expression of other stress-related genes was also impacted in Fld-expressing transgenics. Our data establish a key role of Fld in modulating plant growth and development and plant response to multiple sources of adverse environmental conditions in crop species. This demonstrates the feasibility of manipulating Fld in crop species for genetic engineering of plant stress tolerance.
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Affiliation(s)
- Zhigang Li
- College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanHubeiChina
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
| | - Shuangrong Yuan
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
| | - Haiyan Jia
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
- The Applied Plant Genomics Laboratory of Crop Genomics and Bioinformatics Centreand National Key Laboratory of Crop Genetics and Germplasm EnhancementNanjing Agricultural UniversityNanjingJiangsuChina
| | - Fangyuan Gao
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
- Crop Research InstituteSichuan Academy of Agricultural SciencesChengduSichuanChina
| | - Man Zhou
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
| | - Ning Yuan
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
| | - Peipei Wu
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
| | - Qian Hu
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
| | - Dongfa Sun
- College of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanHubeiChina
| | - Hong Luo
- Department of Genetics and BiochemistryClemson UniversityClemsonSCUSA
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25
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Graff van Creveld S, Rosenwasser S, Levin Y, Vardi A. Chronic Iron Limitation Confers Transient Resistance to Oxidative Stress in Marine Diatoms. Plant Physiol 2016; 172:968-979. [PMID: 27503604 PMCID: PMC5047098 DOI: 10.1104/pp.16.00840] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 08/02/2016] [Indexed: 05/04/2023]
Abstract
Diatoms are single-celled, photosynthetic, bloom-forming algae that are responsible for at least 20% of global primary production. Nevertheless, more than 30% of the oceans are considered "ocean deserts" due to iron limitation. We used the diatom Phaeodactylum tricornutum as a model system to explore diatom's response to iron limitation and its interplay with susceptibility to oxidative stress. By analyzing physiological parameters and proteome profiling, we defined two distinct phases: short-term (<3 d, phase I) and chronic (>5 d, phase II) iron limitation. While at phase I no significant changes in physiological parameters were observed, molecular markers for iron starvation, such as Iron Starvation Induced Protein and flavodoxin, were highly up-regulated. At phase II, down-regulation of numerous iron-containing proteins was detected in parallel to reduction in growth rate, chlorophyll content, photosynthetic activity, respiration rate, and antioxidant capacity. Intriguingly, while application of oxidative stress to phase I and II iron-limited cells similarly oxidized the reduced glutathione (GSH) pool, phase II iron limitation exhibited transient resistance to oxidative stress, despite the down regulation of many antioxidant proteins. By comparing proteomic profiles of P. tricornutum under iron limitation and metatranscriptomic data of an iron enrichment experiment conducted in the Pacific Ocean, we propose that iron-limited cells in the natural environment resemble the phase II metabolic state. These results provide insights into the trade-off between optimal growth rate and susceptibility to oxidative stress in the response of diatoms to iron quota in the marine environment.
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Affiliation(s)
- Shiri Graff van Creveld
- Department of Plant and Environmental Sciences (S.G.v.C., S.R., A.V.),and Israel National Center for Personalized Medicine (Y.L.), Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Shilo Rosenwasser
- Department of Plant and Environmental Sciences (S.G.v.C., S.R., A.V.),and Israel National Center for Personalized Medicine (Y.L.), Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yishai Levin
- Department of Plant and Environmental Sciences (S.G.v.C., S.R., A.V.),and Israel National Center for Personalized Medicine (Y.L.), Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Assaf Vardi
- Department of Plant and Environmental Sciences (S.G.v.C., S.R., A.V.),and Israel National Center for Personalized Medicine (Y.L.), Weizmann Institute of Science, Rehovot 7610001, Israel
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26
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Rodríguez-Cárdenas Á, Rojas AL, Conde-Giménez M, Velázquez-Campoy A, Hurtado-Guerrero R, Sancho J. Streptococcus pneumoniae TIGR4 Flavodoxin: Structural and Biophysical Characterization of a Novel Drug Target. PLoS One 2016; 11:e0161020. [PMID: 27649488 PMCID: PMC5029806 DOI: 10.1371/journal.pone.0161020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 07/28/2016] [Indexed: 12/30/2022] Open
Abstract
Streptococcus pneumoniae (Sp) strain TIGR4 is a virulent, encapsulated serotype that causes bacteremia, otitis media, meningitis and pneumonia. Increased bacterial resistance and limited efficacy of the available vaccine to some serotypes complicate the treatment of diseases associated to this microorganism. Flavodoxins are bacterial proteins involved in several important metabolic pathways. The Sp flavodoxin (Spfld) gene was recently reported to be essential for the establishment of meningitis in a rat model, which makes SpFld a potential drug target. To facilitate future pharmacological studies, we have cloned and expressed SpFld in E. coli and we have performed an extensive structural and biochemical characterization of both the apo form and its active complex with the FMN cofactor. SpFld is a short-chain flavodoxin containing 146 residues. Unlike the well-characterized long-chain apoflavodoxins, the Sp apoprotein displays a simple two-state thermal unfolding equilibrium and binds FMN with moderate affinity. The X-ray structures of the apo and holo forms of SpFld differ at the FMN binding site, where substantial rearrangement of residues at the 91-100 loop occurs to permit cofactor binding. This work will set up the basis for future studies aiming at discovering new potential drugs to treat S. pneumoniae diseases through the inhibition of SpFld.
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Affiliation(s)
- Ángela Rodríguez-Cárdenas
- Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza, Zaragoza, Spain
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Joint Unit IQFR-CSIC-BIFI, Joint Unit EEAD-CSIC-BIFI, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Zaragoza, Spain
| | - Adriana L. Rojas
- Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, Derio, Spain
| | - María Conde-Giménez
- Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza, Zaragoza, Spain
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Joint Unit IQFR-CSIC-BIFI, Joint Unit EEAD-CSIC-BIFI, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Zaragoza, Spain
| | - Adrián Velázquez-Campoy
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Joint Unit IQFR-CSIC-BIFI, Joint Unit EEAD-CSIC-BIFI, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), University of Zaragoza, Zaragoza, Spain
- Fundación ARAID, Government of Aragón, Zaragoza, Spain
| | - Ramón Hurtado-Guerrero
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Joint Unit IQFR-CSIC-BIFI, Joint Unit EEAD-CSIC-BIFI, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), University of Zaragoza, Zaragoza, Spain
- Fundación ARAID, Government of Aragón, Zaragoza, Spain
- * E-mail: (RHG); (JS)
| | - Javier Sancho
- Department of Biochemistry and Molecular and Cell Biology, University of Zaragoza, Zaragoza, Spain
- Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Joint Unit IQFR-CSIC-BIFI, Joint Unit EEAD-CSIC-BIFI, Mariano Esquillor s/n, Campus Rio Ebro, Edificio I+D, Zaragoza, Spain
- Aragon Health Research Institute (IIS Aragón), University of Zaragoza, Zaragoza, Spain
- * E-mail: (RHG); (JS)
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Lodeyro AF, Giró M, Poli HO, Bettucci G, Cortadi A, Ferri AM, Carrillo N. Suppression of Reactive Oxygen Species Accumulation in Chloroplasts Prevents Leaf Damage but Not Growth Arrest in Salt-Stressed Tobacco Plants. PLoS One 2016; 11:e0159588. [PMID: 27441560 PMCID: PMC4956149 DOI: 10.1371/journal.pone.0159588] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 07/06/2016] [Indexed: 11/19/2022] Open
Abstract
Crop yield reduction due to salinity is a growing agronomical concern in many regions. Increased production of reactive oxygen species (ROS) in plant cells accompanies many abiotic stresses including salinity, acting as toxic and signaling molecules during plant stress responses. While ROS are generated in various cellular compartments, chloroplasts represent a main source in the light, and plastid ROS synthesis and/or elimination have been manipulated to improve stress tolerance. Transgenic tobacco plants expressing a plastid-targeted cyanobacterial flavodoxin, a flavoprotein that prevents ROS accumulation specifically in chloroplasts, displayed increased tolerance to many environmental stresses, including drought, excess irradiation, extreme temperatures and iron starvation. Surprisingly, flavodoxin expression failed to protect transgenic plants against NaCl toxicity. However, when high salt was directly applied to leaf discs, flavodoxin did increase tolerance, as reflected by preservation of chlorophylls, carotenoids and photosynthetic activities. Flavodoxin decreased salt-dependent ROS accumulation in leaf tissue from discs and whole plants, but this decline did not improve tolerance at the whole plant level. NaCl accumulation in roots, as well as increased osmotic pressure and salt-induced root damage, were not prevented by flavodoxin expression. The results indicate that ROS formed in chloroplasts have a marginal effect on plant responses during salt stress, and that sensitive targets are present in roots which are not protected by flavodoxin.
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Affiliation(s)
- Anabella F. Lodeyro
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
| | - Mariana Giró
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
| | - Hugo O. Poli
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
| | - Gabriel Bettucci
- Department of Biological Sciences, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
| | - Adriana Cortadi
- Department of Biological Sciences, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
| | - Alejandro M. Ferri
- Department of Analytical Chemistry, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000, Rosario, Argentina
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Li L, Naseem S, Sharma S, Konopka JB. Flavodoxin-Like Proteins Protect Candida albicans from Oxidative Stress and Promote Virulence. PLoS Pathog 2015; 11:e1005147. [PMID: 26325183 PMCID: PMC4556627 DOI: 10.1371/journal.ppat.1005147] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/13/2015] [Indexed: 12/26/2022] Open
Abstract
The fungal pathogen Candida albicans causes lethal systemic infections in humans. To better define how pathogens resist oxidative attack by the immune system, we examined a family of four Flavodoxin-Like Proteins (FLPs) in C. albicans. In agreement with previous studies showing that FLPs in bacteria and plants act as NAD(P)H quinone oxidoreductases, a C. albicans quadruple mutant lacking all four FLPs (pst1Δ, pst2Δ, pst3Δ, ycp4Δ) was more sensitive to benzoquinone. Interestingly, the quadruple mutant was also more sensitive to a variety of oxidants. Quinone reductase activity confers important antioxidant effects because resistance to oxidation was restored in the quadruple mutant by expressing either Escherichia coli wrbA or mammalian NQO1, two distinct types of quinone reductases. FLPs were detected at the plasma membrane in C. albicans, and the quadruple mutant was more sensitive to linolenic acid, a polyunsaturated fatty acid that can auto-oxidize and promote lipid peroxidation. These observations suggested that FLPs reduce ubiquinone (coenzyme Q), enabling it to serve as an antioxidant in the membrane. In support of this, a C. albicans coq3Δ mutant that fails to synthesize ubiquinone was also highly sensitive to oxidative stress. FLPs are critical for survival in the host, as the quadruple mutant was avirulent in a mouse model of systemic candidiasis under conditions where infection with wild type C. albicans was lethal. The quadruple mutant cells initially grew well in kidneys, the major site of C. albicans growth in mice, but then declined after the influx of neutrophils and by day 4 post-infection 33% of the mice cleared the infection. Thus, FLPs and ubiquinone are important new antioxidant mechanisms that are critical for fungal virulence. The potential of FLPs as novel targets for antifungal therapy is further underscored by their absence in mammalian cells.
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Affiliation(s)
- Lifang Li
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Shamoon Naseem
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Sahil Sharma
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - James B. Konopka
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
- * E-mail:
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29
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Chappell PD, Whitney LP, Wallace JR, Darer AI, Jean-Charles S, Jenkins BD. Genetic indicators of iron limitation in wild populations of Thalassiosira oceanica from the northeast Pacific Ocean. ISME J 2015; 9:592-602. [PMID: 25333460 PMCID: PMC4331588 DOI: 10.1038/ismej.2014.171] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 05/15/2014] [Accepted: 07/11/2014] [Indexed: 11/18/2022]
Abstract
Assessing the iron (Fe) nutritional status of natural diatom populations has proven challenging as physiological and molecular responses can differ in diatoms of the same genus. We evaluated expression of genes encoding flavodoxin (FLDA1) and an Fe-starvation induced protein (ISIP3) as indicators of Fe limitation in the marine diatom Thalassiosira oceanica. The specificity of the response to Fe limitation was tested in cultures grown under Fe- and macronutrient-deficient conditions, as well as throughout the diurnal light cycle. Both genes showed a robust and specific response to Fe limitation in laboratory cultures and were detected in small volume samples collected from the northeast Pacific, demonstrating the sensitivity of this method. Overall, FLDA1 and ISIP3 expression was inversely related to Fe concentrations and offered insight into the Fe nutritional health of T. oceanica in the field. As T. oceanica is a species tolerant to low Fe, indications of Fe limitation in T. oceanica populations may serve as a proxy for severe Fe stress in the overall diatom community. At two shallow coastal locations, FLD1A and ISIP3 expression revealed Fe stress in areas where dissolved Fe concentrations were high, demonstrating that this approach may be powerful for identifying regions where Fe supply may not be biologically available.
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Affiliation(s)
- P Dreux Chappell
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, USA
| | - LeAnn P Whitney
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, USA
| | - Joselynn R Wallace
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, USA
| | - Adam I Darer
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, USA
| | - Samua Jean-Charles
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, USA
| | - Bethany D Jenkins
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, RI, USA
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
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Gharechahi J, Hajirezaei MR, Salekdeh GH. Comparative proteomic analysis of tobacco expressing cyanobacterial flavodoxin and its wild type under drought stress. J Plant Physiol 2015; 175:48-58. [PMID: 25506766 DOI: 10.1016/j.jplph.2014.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 11/05/2014] [Accepted: 11/13/2014] [Indexed: 05/02/2023]
Abstract
Tobacco plants expressing cyanobacterial flavodoxin (Fld) show enhanced tolerance to a wide range of abiotic stresses including drought, temperature and UV. The mechanisms of adaptation to stress conditions under Fld expression are largely unknown. Here, we applied comparative proteomic analysis to uncover the changes in the proteome profile of Fld-expressing plants in response to drought stress. Using high-resolution two-dimensional gel electrophoresis, we were able to detect 930 protein spots and compare their abundance. We found changes up to 1.5 fold for 52 spots under drought in transgenic and/or wild type plants. Using combined MALDI-TOF/TOF and ESI-Q/TOF analysis 39 (24 in wild type, 11 in transgenic, and 4 in both) drought-responsive proteins (DRPs) could be identified. The majority of DRPs are known to be involved in photosynthesis, carbohydrate and energy metabolism, amino acid and protein synthesis and processing, and oxidative stress responses. Among candidate DRPs, the abundance of remurin, ferredoxin-NADP reductase, chloroplast manganese stabilizing protein-II, phosphoglycerate mutase, and glutathione S-transferase decreased in drought stressed Fld-tobacco while S-formylglutathione hydrolase and pyridoxine biosynthesis protein abundance increased. In wild type plants, drought caused a reduction of proteins related to carbohydrate metabolism. These results suggest that the stress tolerance conferred by Fld expression is strongly related to control mechanisms regarding carbohydrate and energy metabolism as well as oxidative stress responses.
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Affiliation(s)
- Javad Gharechahi
- Department of Systems Biology, Agricultural Biotechnology Research Institute of Iran (ABRII), Karaj, Iran
| | - Mohammad-Reza Hajirezaei
- Leibniz Institute of Plant Genetics and Crop Plant Research (Leibniz-IPK), Corrensstraße 3, 06466 Gatersleben, Germany
| | - Ghasem Hosseini Salekdeh
- Department of Systems Biology, Agricultural Biotechnology Research Institute of Iran (ABRII), Karaj, Iran.
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Culka M, Milichovsky J, Jerabek P, Stiborova M, Martinek V. Ferrous and ferric state of cytochromes P450 in intact Escherichia coli cells: a possible role of cytochrome P450-flavodoxin interactions. Neuro Endocrinol Lett 2015; 36 Suppl 1:29-37. [PMID: 26757119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 09/09/2015] [Indexed: 06/05/2023]
Abstract
OBJECTIVES Cytochromes P450 (CYPs) are heme enzymes oxygenating a broad range of substrates. Their activity is dependent on the presence of a suitable electron donor (eukaryotic NADPH:CYP oxidoreductase or cytochrome b5). The Escherichia naturally contain no CYPs and no NADPH:CYP oxidoreductase, however it was reported that some CYPs heterologously expressed in E. coli may exist in the ferrous form. A small bacterial flavoprotein, flavodoxin is considered to be responsible for reduction some of these CYPs. METHODS The reduction state of several human CYPs expressed in the intact living E. coli cells was examined. In addition, molecular dynamics and steered molecular dynamics simulations were performed to predict and compare affinity of flavodoxin toward selected CYPs. RESULTS We determined the reduction state of five human CYPs heterologously expressed in E. coli. The computationally predicted stabilities of CYP-flavodoxin complexes correlate with the percentage of reduced CYPs in bacterial cells. The mean electron transfer distance within optimized complexes was also related to the percentage of reduced CYPs. CONCLUSION Depending on the resting state, the CYPs heterologously expressed in E. coli could be divided into two groups; CYP2C8, 2C9, 3A4 are in E. coli present mainly in the oxidized form; while CYP1A1, 1A2, 2A6, 2A13, 2B6, 2D6 are found predominantly in the reduced form. We found a significant correlation between the stability of CYP-flavodoxin complexes and the percentage of reduced CYPs in bacteria. Hence, the naturally expressed flavodoxin is probably responsible for reduction of a larger group of human CYPs in bacterial cells.
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Affiliation(s)
- Martin Culka
- Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jan Milichovsky
- Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Petr Jerabek
- Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Marie Stiborova
- Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Vaclav Martinek
- Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
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Pierella Karlusich JJ, Lodeyro AF, Carrillo N. The long goodbye: the rise and fall of flavodoxin during plant evolution. J Exp Bot 2014; 65:5161-78. [PMID: 25009172 PMCID: PMC4400536 DOI: 10.1093/jxb/eru273] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 05/27/2014] [Accepted: 05/28/2014] [Indexed: 05/18/2023]
Abstract
Ferredoxins are electron shuttles harbouring iron-sulfur clusters that connect multiple oxido-reductive pathways in organisms displaying different lifestyles. Some prokaryotes and algae express an isofunctional electron carrier, flavodoxin, which contains flavin mononucleotide as cofactor. Both proteins evolved in the anaerobic environment preceding the appearance of oxygenic photosynthesis. The advent of an oxygen-rich atmosphere proved detrimental to ferredoxin owing to iron limitation and oxidative damage to the iron-sulfur cluster, and many microorganisms induced flavodoxin expression to replace ferredoxin under stress conditions. Paradoxically, ferredoxin was maintained throughout the tree of life, whereas flavodoxin is absent from plants and animals. Of note is that flavodoxin expression in transgenic plants results in increased tolerance to multiple stresses and iron deficit, through mechanisms similar to those operating in microorganisms. Then, the question remains open as to why a trait that still confers plants such obvious adaptive benefits was not retained. We compare herein the properties of ferredoxin and flavodoxin, and their contrasting modes of expression in response to different environmental stimuli. Phylogenetic analyses suggest that the flavodoxin gene was already absent in the algal lineages immediately preceding land plants. Geographical distribution of phototrophs shows a bias against flavodoxin-containing organisms in iron-rich coastal/freshwater habitats. Based on these observations, we propose that plants evolved from freshwater macroalgae that already lacked flavodoxin because they thrived in an iron-rich habitat with no need to back up ferredoxin functions and therefore no selective pressure to keep the flavodoxin gene. Conversely, ferredoxin retention in the plant lineage is probably related to its higher efficiency as an electron carrier, compared with flavodoxin. Several lines of evidence supporting these contentions are presented and discussed.
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Affiliation(s)
- Juan J Pierella Karlusich
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
| | - Anabella F Lodeyro
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
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Ye Q, Hu Y, Jin C. Conformational dynamics of Escherichia coli flavodoxins in apo- and holo-states by solution NMR spectroscopy. PLoS One 2014; 9:e103936. [PMID: 25093851 PMCID: PMC4122359 DOI: 10.1371/journal.pone.0103936] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 07/08/2014] [Indexed: 11/23/2022] Open
Abstract
Flavodoxins are a family of small FMN-binding proteins that commonly exist in prokaryotes. They utilize a non-covalently bound FMN molecule to act as the redox center during the electron transfer processes in various important biological pathways. Although extensive investigations were performed, detailed molecular mechanisms of cofactor binding and electron transfer remain elusive. Herein we report the solution NMR studies on Escherichia coli flavodoxins FldA and YqcA, belonging to the long-chain and short-chain flavodoxin subfamilies respectively. Our structural studies demonstrate that both proteins show the typical flavodoxin fold, with extensive conformational exchanges observed near the FMN binding pocket in their apo-forms. Cofactor binding significantly stabilizes both proteins as revealed by the extension of secondary structures in the holo-forms, and the overall rigidity shown by the backbone dynamics data. However, the 50 s loops of both proteins in the holo-form still show conformational exchanges on the µs-ms timescales, which appears to be a common feature in the flavodoxin family, and might play an important role in structural fine-tuning during the electron transfer reactions.
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Affiliation(s)
- Qian Ye
- Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing, China
- College of Life Sciences, Peking University, Beijing, China
| | - Yunfei Hu
- Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing, China
- College of Chemistry and Molecular Engineering, Peking University, Beijing, China
- * E-mail: (YF); (CJ)
| | - Changwen Jin
- Beijing Nuclear Magnetic Resonance Center, Peking University, Beijing, China
- College of Life Sciences, Peking University, Beijing, China
- College of Chemistry and Molecular Engineering, Peking University, Beijing, China
- Beijing National Laboratory for Molecular Sciences, Peking University, Beijing, China
- * E-mail: (YF); (CJ)
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Moyano AJ, Tobares RA, Rizzi YS, Krapp AR, Mondotte JA, Bocco JL, Saleh MC, Carrillo N, Smania AM. A long-chain flavodoxin protects Pseudomonas aeruginosa from oxidative stress and host bacterial clearance. PLoS Genet 2014; 10:e1004163. [PMID: 24550745 PMCID: PMC3923664 DOI: 10.1371/journal.pgen.1004163] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 12/20/2013] [Indexed: 12/12/2022] Open
Abstract
Long-chain flavodoxins, ubiquitous electron shuttles containing flavin mononucleotide (FMN) as prosthetic group, play an important protective role against reactive oxygen species (ROS) in various microorganisms. Pseudomonas aeruginosa is an opportunistic pathogen which frequently has to face ROS toxicity in the environment as well as within the host. We identified a single ORF, hereafter referred to as fldP (for flavodoxin from P. aeruginosa), displaying the highest similarity in length, sequence identity and predicted secondary structure with typical long-chain flavodoxins. The gene was cloned and expressed in Escherichia coli. The recombinant product (FldP) could bind FMN and exhibited flavodoxin activity in vitro. Expression of fldP in P. aeruginosa was induced by oxidative stress conditions through an OxyR-independent mechanism, and an fldP-null mutant accumulated higher intracellular ROS levels and exhibited decreased tolerance to H2O2 toxicity compared to wild-type siblings. The mutant phenotype could be complemented by expression of a cyanobacterial flavodoxin. Overexpression of FldP in a mutT-deficient P. aeruginosa strain decreased H2O2-induced cell death and the hypermutability caused by DNA oxidative damage. FldP contributed to the survival of P. aeruginosa within cultured mammalian macrophages and in infected Drosophila melanogaster, which led in turn to accelerated death of the flies. Interestingly, the fldP gene is present in some but not all P. aeruginosa strains, constituting a component of the P. aeruginosa accessory genome. It is located in a genomic island as part of a self-regulated polycistronic operon containing a suite of stress-associated genes. The collected results indicate that the fldP gene encodes a long-chain flavodoxin, which protects the cell from oxidative stress, thereby expanding the capabilities of P. aeruginosa to thrive in hostile environments. Coping with toxic reactive oxygen species (ROS) generated as by-products of aerobic metabolism is a major challenge for O2-thriving organisms, which deploy multilevel responses to prevent ROS-triggered damage, including membrane modifications, induction of antioxidant and repair systems and/or replacement of ROS-sensitive targets by resistant isofunctional versions, among others. The opportunistic pathogen Pseudomonas aeruginosa is frequently exposed to ROS in the environment as well as within the host, and we describe herein a new response by which this microorganism can deal with oxidative stress. This pathway depends on a previously uncharacterized gene that we named fldP (for flavodoxin from P. aeruginosa), which encodes a flavoprotein that belongs to the family of long-chain flavodoxins. FldP exhibited a protective role against ROS-dependent physiological and mutational damage, and contributed to the survival of P. aeruginosa during in vivo infection of flies as well as within mammalian macrophagic cells. Thus, fldP increases the adaptive repertoire of P. aeruginosa to face oxidative stress.
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Affiliation(s)
- Alejandro J. Moyano
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Romina A. Tobares
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Yanina S. Rizzi
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Adriana R. Krapp
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Juan A. Mondotte
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR3569, Paris, France
| | - José L. Bocco
- Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI), CONICET, Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Maria-Carla Saleh
- Institut Pasteur, Viruses and RNA Interference, Centre National de la Recherche Scientifique UMR3569, Paris, France
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Andrea M. Smania
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
- * E-mail:
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Abstract
Intraprotein electron transfer (ET) in flavoproteins is important for understanding the correlation of their redox, configuration, and reactivity at the active site. Here, we used oxidized flavodoxin as a model system and report our complete characterization of a photoinduced redox cycle from the initial charge separation in 135-340 fs to subsequent charge recombination in 0.95-1.6 ps and to the final cooling relaxation of the product(s) in 2.5-4.3 ps. With 11 mutations at the active site, we observed that these ultrafast ET dynamics, much faster than active-site relaxation, mainly depend on the reduction potentials of the electron donors with minor changes caused by mutations, reflecting a highly localized ET reaction between the stacked donor and acceptor at a van der Waals distance and leading to a gas-phase type of bimolecular ET reaction confined in the active-site nanospace. Significantly, these ultrafast ET reactions ensure our direct observation of vibrationally excited reaction product(s), suggesting that the back ET barrier is effectively reduced because of the decrease in the total free energy in the Marcus inverted region, leading to the accelerated charge recombination. Such vibrationally coupled charge recombination should be a general feature of flavoproteins with similar configurations and interactions between the cofactor flavin and neighboring aromatic residues.
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Affiliation(s)
| | | | - Xunmin Guo
- Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Chih-Wei Chang
- Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Lijuan Wang
- Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, OH 43210
| | - Dongping Zhong
- Department of Physics, Department of Chemistry and Biochemistry, and Programs of Biophysics, Chemical Physics, and Biochemistry, The Ohio State University, Columbus, OH 43210
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Feng J, Wu J, Dai N, Lin S, Xu HH, Deng Z, He X. Discovery and characterization of BlsE, a radical S-adenosyl-L-methionine decarboxylase involved in the blasticidin S biosynthetic pathway. PLoS One 2013; 8:e68545. [PMID: 23874663 PMCID: PMC3715490 DOI: 10.1371/journal.pone.0068545] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/30/2013] [Indexed: 11/19/2022] Open
Abstract
BlsE, a predicted radical S-adenosyl-L-methionine (SAM) protein, was anaerobically purified and reconstituted in vitro to study its function in the blasticidin S biosynthetic pathway. The putative role of BlsE was elucidated based on bioinformatics analysis, genetic inactivation and biochemical characterization. Biochemical results showed that BlsE is a SAM-dependent radical enzyme that utilizes cytosylglucuronic acid, the accumulated intermediate metabolite in blsE mutant, as substrate and catalyzes decarboxylation at the C5 position of the glucoside residue to yield cytosylarabinopyranose. Additionally, we report the purification and reconstitution of BlsE, characterization of its [4Fe-4S] cluster using UV-vis and electron paramagnetic resonance (EPR) spectroscopic analysis, and investigation of the ability of flavodoxin (Fld), flavodoxin reductase (Fpr) and NADPH to reduce the [4Fe-4S](2+) cluster. Mutagenesis studies demonstrated that Cys31, Cys35, Cys38 in the C×××C×MC motif and Gly73, Gly74, Glu75, Pro76 in the GGEP motif were crucial amino acids for BlsE activity while mutation of Met37 had little effect on its function. Our results indicate that BlsE represents a typical [4Fe-4S]-containing radical SAM enzyme and it catalyzes decarboxylation in blasticidin S biosynthesis.
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Affiliation(s)
- Jun Feng
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Jun Wu
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Nan Dai
- New England Biolabs, Inc., Research Department, Ipswich, Massachusetts, United States of America
| | - Shuangjun Lin
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - H. Howard Xu
- Department of Biological Sciences, California State University Los Angeles, Los Angeles, California, United States of America
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Xinyi He
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
- * E-mail:
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Hsieh YC, Chia TS, Fun HK, Chen CJ. Crystal structure of dimeric flavodoxin from Desulfovibrio gigas suggests a potential binding region for the electron-transferring partner. Int J Mol Sci 2013; 14:1667-83. [PMID: 23322018 PMCID: PMC3565340 DOI: 10.3390/ijms14011667] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 12/03/2012] [Accepted: 12/25/2012] [Indexed: 11/16/2022] Open
Abstract
Flavodoxins, which exist widely in microorganisms, have been found in various pathways with multiple physiological functions. The flavodoxin (Fld) containing the cofactor flavin mononucleotide (FMN) from sulfur-reducing bacteria Desulfovibrio gigas (D. gigas) is a short-chain enzyme that comprises 146 residues with a molecular mass of 15 kDa and plays important roles in the electron-transfer chain. To investigate its structure, we purified this Fld directly from anaerobically grown D. gigas cells. The crystal structure of Fld, determined at resolution 1.3 Å, is a dimer with two FMN packing in an orientation head to head at a distance of 17 Å, which generates a long and connected negatively charged region. Two loops, Thr59-Asp63 and Asp95-Tyr100, are located in the negatively charged region and between two FMN, and are structurally dynamic. An analysis of each monomer shows that the structure of Fld is in a semiquinone state; the positions of FMN and the surrounding residues in the active site deviate. The crystal structure of Fld from D. gigas agrees with a dimeric form in the solution state. The dimerization area, dynamic characteristics and structure variations between monomers enable us to identify a possible binding area for its functional partners.
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Affiliation(s)
- Yin-Cheng Hsieh
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan; E-Mail:
| | - Tze Shyang Chia
- X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia; E-Mails: (T.S.C.); (H.-K.F.)
| | - Hoong-Kun Fun
- X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia; E-Mails: (T.S.C.); (H.-K.F.)
- Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia; E-Mail:
| | - Chun-Jung Chen
- Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan; E-Mail:
- Department of Physics, National Tsing Hua University, Hsinchu 30043, Taiwan
- Institute of Biotechnology, National Cheng Kung University, Tainan City 70101, Taiwan
- University Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan City 70101, Taiwan
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +886-3-5780281 (ext. 7330); Fax: +886-3-5783813
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Redondo FJ, Coba de la Peña T, Lucas MM, Pueyo JJ. Alfalfa nodules elicited by a flavodoxin-overexpressing Ensifer meliloti strain display nitrogen-fixing activity with enhanced tolerance to salinity stress. Planta 2012; 236:1687-1700. [PMID: 22864594 DOI: 10.1007/s00425-012-1725-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 07/19/2012] [Indexed: 06/01/2023]
Abstract
Nitrogen fixation by legumes is very sensitive to salinity stress, which can severely reduce the productivity of legume crops and their soil-enriching capacity. Salinity is known to cause oxidative stress in the nodule by generating reactive oxygen species (ROS). Flavodoxins are involved in the response to oxidative stress in bacteria and cyanobacteria. Prevention of ROS production by flavodoxin overexpression in bacteroids might lead to a protective effect on nodule functioning under salinity stress. Tolerance to salinity stress was evaluated in alfalfa nodules elicited by an Ensifer meliloti strain that overexpressed a cyanobacterial flavodoxin compared with nodules produced by the wild-type bacteria. Nitrogen fixation, antioxidant and carbon metabolism enzyme activities were determined. The decline in nitrogenase activity associated to salinity stress was significantly less in flavodoxin-expressing than in wild-type nodules. We detected small but significant changes in nodule antioxidant metabolism involving the ascorbate-glutathione cycle enzymes and metabolites, as well as differences in activity of the carbon metabolism enzyme sucrose synthase, and an atypical starch accumulation pattern in flavodoxin-containing nodules. Salt-induced structural and ultrastructural alterations were examined in detail in alfalfa wild-type nodules by light and electron microscopy and compared to flavodoxin-containing nodules. Flavodoxin reduced salt-induced structural damage, which primarily affected young infected tissues and not fully differentiated bacteroids. The results indicate that overexpression of flavodoxin in bacteroids has a protective effect on the function and structure of alfalfa nodules subjected to salinity stress conditions. Putative protection mechanisms are discussed.
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Ceccoli RD, Blanco NE, Segretin ME, Melzer M, Hanke GT, Scheibe R, Hajirezaei MR, Bravo-Almonacid FF, Carrillo N. Flavodoxin displays dose-dependent effects on photosynthesis and stress tolerance when expressed in transgenic tobacco plants. Planta 2012; 236:1447-58. [PMID: 22763502 DOI: 10.1007/s00425-012-1695-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 06/16/2012] [Indexed: 05/18/2023]
Abstract
Ferredoxins are iron-sulfur proteins involved in various one-electron transfer pathways. Ferredoxin levels decrease under adverse environmental conditions in photosynthetic organisms. In cyanobacteria, this decline is compensated by induction of flavodoxin, an isofunctional flavoprotein. Flavodoxin is not present in higher plants, but transgenic Nicotiana tabacum lines accumulating Anabaena flavodoxin in plastids display increased tolerance to different sources of environmental stress. As the degree of tolerance correlated with flavodoxin dosage in plastids of nuclear-transformed transgenic tobacco, we prepared plants expressing even higher levels of flavodoxin by direct plastid transformation. A suite of nuclear- and chloroplast-transformed lines expressing a wide range of flavodoxin levels, from 0.3 to 10.8 μmol m(-2), did not exhibit any detectable growth phenotype relative to the wild type. In the absence of stress, the contents of both chlorophyll a and carotenoids, as well as the photosynthetic performance (photosystem II maximum efficiency, photosystem II operating efficiency, electron transport rates and carbon assimilation rates), displayed a moderate increase with flavodoxin concentrations up to 1.3-2.6 μmol flavodoxin m(-2), and then declined to wild-type levels. Stress tolerance, as estimated by the damage inflicted on exposure to the pro-oxidant methyl viologen, also exhibited a bell-shaped response, with a significant, dose-dependent increase in tolerance followed by a drop in the high-expressing lines. The results indicate that optimal photosynthetic performance and stress tolerance were observed at flavodoxin levels comparable to those of endogenous ferredoxin. Further increases in flavodoxin content become detrimental to plant fitness.
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Affiliation(s)
- Romina D Ceccoli
- División Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario, Universidad Nacional de Rosario, Suipacha 531, S2002LRK, Rosario, Argentina
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40
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Lans I, Frago S, Medina M. Understanding the FMN cofactor chemistry within the Anabaena Flavodoxin environment. Biochim Biophys Acta 2012; 1817:2118-27. [PMID: 22982476 DOI: 10.1016/j.bbabio.2012.08.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 08/26/2012] [Accepted: 08/31/2012] [Indexed: 11/19/2022]
Abstract
The chemical versatility of flavin cofactors within the flavoprotein environment allows them to play main roles in the bioenergetics of all type of organisms, particularly in energy transformation processes such as photosynthesis or oxidative phosphorylation. Despite the large diversity of properties shown by flavoproteins and of the biological processes in which they are involved, only two flavin cofactors, FMN and FAD (both derived from the 7,8-dimethyl-10-(1'-D-ribityl)-isoalloxazine), are usually found in these proteins. Using theoretical and experimental approaches we have carried out an evaluation of the effects introduced upon substituting the 7- and/or 8-methyls of the isoalloxazine ring in the chemical and oxido-reduction properties of the different atoms of the ring on free flavins and on the photosynthetic Anabaena Flavodoxin (a flavoprotein that replaces Ferredoxin as electron carrier from Photosystem I to Ferredoxin-NADP(+) reductase). In Anabaena Flavodoxin both the protein environment and the redox state contribute to modulate the chemical reactivity of the isoalloxazine ring. Anabaena apoflavodoxin is shown to be designed to stabilise/destabilise each one of the FMN redox states (but not of the analogues produced upon substitution of the 7- and/or 8-methyls groups) in the adequate proportions to provide Flavodoxin with the particular properties required for the functions in which it is involved in vivo. The 7- and/or 8-methyl groups of the ixoalloxazine can be discarded as the gate for electrons exchange in Anabaena Fld, but a key role in this process is envisaged for the C6 atom of the flavin and the backbone atoms of Asn58.
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Affiliation(s)
- Isaias Lans
- Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, 50009, Zaragoza, Spain
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41
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Lindhoud S, van den Berg WAM, van den Heuvel RHH, Heck AJR, van Mierlo CPM, van Berkel WJH. Cofactor binding protects flavodoxin against oxidative stress. PLoS One 2012; 7:e41363. [PMID: 22829943 PMCID: PMC3400614 DOI: 10.1371/journal.pone.0041363] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 06/20/2012] [Indexed: 11/23/2022] Open
Abstract
In organisms, various protective mechanisms against oxidative damaging of proteins exist. Here, we show that cofactor binding is among these mechanisms, because flavin mononucleotide (FMN) protects Azotobacter vinelandii flavodoxin against hydrogen peroxide-induced oxidation. We identify an oxidation sensitive cysteine residue in a functionally important loop close to the cofactor, i.e., Cys69. Oxidative stress causes dimerization of apoflavodoxin (i.e., flavodoxin without cofactor), and leads to consecutive formation of sulfinate and sulfonate states of Cys69. Use of 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) reveals that Cys69 modification to a sulfenic acid is a transient intermediate during oxidation. Dithiothreitol converts sulfenic acid and disulfide into thiols, whereas the sulfinate and sulfonate forms of Cys69 are irreversible with respect to this reagent. A variable fraction of Cys69 in freshly isolated flavodoxin is in the sulfenic acid state, but neither oxidation to sulfinic and sulfonic acid nor formation of intermolecular disulfides is observed under oxidising conditions. Furthermore, flavodoxin does not react appreciably with NBD-Cl. Besides its primary role as redox-active moiety, binding of flavin leads to considerably improved stability against protein unfolding and to strong protection against irreversible oxidation and other covalent thiol modifications. Thus, cofactors can protect proteins against oxidation and modification.
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Affiliation(s)
- Simon Lindhoud
- Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands
| | | | - Robert H. H. van den Heuvel
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Albert J. R. Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
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Bui SH, McLean KJ, Cheesman MR, Bradley JM, Rigby SEJ, Levy CW, Leys D, Munro AW. Unusual spectroscopic and ligand binding properties of the cytochrome P450-flavodoxin fusion enzyme XplA. J Biol Chem 2012; 287:19699-714. [PMID: 22500029 PMCID: PMC3366004 DOI: 10.1074/jbc.m111.319202] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 04/05/2012] [Indexed: 11/06/2022] Open
Abstract
The Rhodococcus rhodochrous strain 11Y XplA enzyme is an unusual cytochrome P450-flavodoxin fusion enzyme that catalyzes reductive denitration of the explosive hexahydro-1,3,5-trinitro-1,3,5-triazene (RDX). We show by light scattering that XplA is a monomeric enzyme. XplA has high affinity for imidazole (K(d) = 1.6 μM), explaining previous reports of a red-shifted XplA Soret band in pure enzyme. The true Soret maximum of XplA is at 417 nm. Similarly, unusually weak XplA flavodoxin FMN binding (K(d) = 1.09 μM) necessitates its purification in the presence of the cofactor to produce hallmark flavin contributions absent in previously reported spectra. Structural and ligand-binding data reveal a constricted active site able to accommodate RDX and small inhibitory ligands (e.g. 4-phenylimidazole and morpholine) while discriminating against larger azole drugs. The crystal structure also identifies a high affinity imidazole binding site, consistent with its low K(d), and shows active site penetration by PEG, perhaps indicative of an evolutionary lipid-metabolizing function for XplA. EPR studies indicate heterogeneity in binding mode for RDX and other ligands. The substrate analog trinitrobenzene does not induce a substrate-like type I optical shift but creates a unique low spin EPR spectrum due to influence on structure around the distal water heme ligand. The substrate-free heme iron potential (-268 mV versus NHE) is positive for a low spin P450, and the elevated potential of the FMN semiquinone/hydroquinone couple (-172 mV) is also an adaptation that may reflect (along with the absence of a key Thr/Ser residue conserved in oxygen-activating P450s) the evolution of XplA as a specialized RDX reductase catalyst.
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Affiliation(s)
- Soi H. Bui
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
| | - Kirsty J. McLean
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
| | - Myles R. Cheesman
- the School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Justin M. Bradley
- the School of Chemical Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Stephen E. J. Rigby
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
| | - Colin W. Levy
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
| | - David Leys
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
| | - Andrew W. Munro
- From the Manchester Interdisciplinary Biocentre, Faculty of Life Sciences, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom and
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Mulrooney SB, Howard MJ, Hausinger RP. The Escherichia coli alkylation response protein AidB is a redox partner of flavodoxin and binds RNA and acyl carrier protein. Arch Biochem Biophys 2011; 513:81-6. [PMID: 21782785 DOI: 10.1016/j.abb.2011.07.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 07/05/2011] [Accepted: 07/07/2011] [Indexed: 11/19/2022]
Abstract
Microorganisms are exposed to a wide variety of exogenous and endogenous chemical agents that alkylate DNA. Escherichia coli cells exhibit an adaptive response that recognizes and repairs alkylated DNA lesions using Ada, AlkA, and AlkB enzymes. Another alkylation response protein, the DNA-binding flavoprotein AidB, was proposed to repair DNA or protect it from chemical alkylating agents, but direct evidence for its role is lacking. Here, AidB was shown to form tight complexes with both flavodoxin and acyl carrier protein. In addition, electron transfer between 1-electron and 2-electron reduced flavodoxin to oxidized AidB was observed, although with very small rate constants. AidB was found to bind to RNA, raising the prospect that the protein may have a role in protection of RNA from chemical alkylation. Finally, the reagent N-methyl-N'-nitro-N-nitrosoguanidine was eliminated as a direct substrate of the enzyme.
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Affiliation(s)
- Scott B Mulrooney
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.
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Blanco NE, Ceccoli RD, Segretin ME, Poli HO, Voss I, Melzer M, Bravo-Almonacid FF, Scheibe R, Hajirezaei MR, Carrillo N. Cyanobacterial flavodoxin complements ferredoxin deficiency in knocked-down transgenic tobacco plants. Plant J 2011; 65:922-35. [PMID: 21205028 DOI: 10.1111/j.1365-313x.2010.04479.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Ferredoxins are the main electron shuttles in chloroplasts, accepting electrons from photosystem I and delivering them to essential oxido-reductive pathways in the stroma. Ferredoxin levels decrease under adverse environmental conditions in both plants and photosynthetic micro-organisms. In cyanobacteria and some algae, this decrease is compensated for by induction of flavodoxin, an isofunctional flavoprotein that can replace ferredoxin in many reactions. Flavodoxin is not present in plants, but tobacco lines expressing a plastid-targeted cyanobacterial flavodoxin developed increased tolerance to environmental stress. Chloroplast-located flavodoxin interacts productively with endogenous ferredoxin-dependent pathways, suggesting that its protective role results from replacement of stress-labile ferredoxin. We tested this hypothesis by using RNA antisense and interference techniques to decrease ferredoxin levels in transgenic tobacco. Ferredoxin-deficient lines showed growth arrest, leaf chlorosis and decreased CO(2) assimilation. Chlorophyll fluorescence measurements indicated impaired photochemistry, over-reduction of the photosynthetic electron transport chain and enhanced non-photochemical quenching. Expression of flavodoxin from the nuclear or plastid genome restored growth, pigment contents and photosynthetic capacity, and relieved the electron pressure on the electron transport chain. Tolerance to oxidative stress also recovered. In the absence of flavodoxin, ferredoxin could not be decreased below 45% of physiological content without fatally compromising plant survival, but in its presence, lines with only 12% remaining ferredoxin could grow autotrophically, with almost wild-type phenotypes. The results indicate that the stress tolerance conferred by flavodoxin expression in plants stems largely from functional complementation of endogenous ferredoxin by the cyanobacterial flavoprotein.
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Affiliation(s)
- Nicolás E Blanco
- División Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET), Universidad Nacional de Rosario, S2002LRK Rosario, Argentina
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Coba de la Peña T, Redondo FJ, Manrique E, Lucas MM, Pueyo JJ. Nitrogen fixation persists under conditions of salt stress in transgenic Medicago truncatula plants expressing a cyanobacterial flavodoxin. Plant Biotechnol J 2010; 8:954-65. [PMID: 20353403 DOI: 10.1111/j.1467-7652.2010.00519.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Several recent studies have demonstrated that the expression of a cyanobacterial flavodoxin in plants can provide tolerance to a wide range of environmental stresses. Indeed, this strategy has been proposed as a potentially powerful biotechnological tool to generate multiple-tolerant crops. To determine whether flavodoxin expression specifically increased tolerance to salt stress and whether it might also preserve legume nitrogen fixation under saline conditions, the flavodoxin gene was introduced into the model legume Medicago truncatula. Expression of flavodoxin did not confer saline tolerance to the whole plant, although the sensitive nitrogen-fixing activity was maintained under salt stress in flavodoxin-expressing plants. Our results indicate that flavodoxin induced small but significant changes in the enzymatic activities involved in the nodule redox balance that might be responsible for the positive effect on nitrogen fixation. Expression of flavodoxin can be regarded as a potential tool to improve legume symbiotic performance under salt stress, and possibly other environmental stresses.
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Affiliation(s)
- Teodoro Coba de la Peña
- Department of Plant Physiology and Ecology, Instituto de Recursos Naturales, Centro de Ciencias Medioambientales, CSIC, Serrano, Madrid, Spain
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Mediavilla MG, Di Venanzio GA, Guibert EE, Tiribelli C. Heterologous ferredoxin reductase and flavodoxin protect Cos-7 cells from oxidative stress. PLoS One 2010; 5:e13501. [PMID: 20976072 PMCID: PMC2957446 DOI: 10.1371/journal.pone.0013501] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 09/27/2010] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Ferredoxin-NADP(H) reductase (FNR) from Pisum sativum and Flavodoxin (Fld) from Anabaena PCC 7119 have been reported to protect a variety of cells and organisms from oxidative insults. In this work, these two proteins were expressed in mitochondria of Cos-7 cells and tested for their efficacy to protect these cells from oxidative stress in vitro. PRINCIPAL FINDINGS Cos-7/pFNR and Cos-7/pFld cell lines expressing FNR and Fld, respectively, showed a significantly higher resistance to 24 h exposure to 300-600 µM hydrogen peroxide measured by LDH retention, MTT reduction, malondialdehyde (MDA) levels and lipid peroxide (LPO; FOX assay) levels. However, FNR and Fld did not exhibit any protection at shorter incubation times (2 h and 4 h) to 4 mM hydrogen peroxide or to a 48 h exposure to 300 µM methyl viologen. We found enhanced methyl viologen damage exerted by FNR that may be due to depletion of NADPH pools through NADPH-MV diaphorase activity as previously observed for other overexpressed enzymes. SIGNIFICANCE The results presented are a first report of antioxidant function of these heterologous enzymes of vegetal and cyanobacterial origin in mammalian cells.
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Affiliation(s)
- María G Mediavilla
- Centro Binacional Argentina-Italia de Investigaciones en Criobiología Clínica y Aplicada CAIC and Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario, Argentina.
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Zurbriggen MD, Carrillo N, Tognetti VB, Melzer M, Peisker M, Hause B, Hajirezaei MR. Chloroplast-generated reactive oxygen species play a major role in localized cell death during the non-host interaction between tobacco and Xanthomonas campestris pv. vesicatoria. Plant J 2009; 60:962-73. [PMID: 19719480 DOI: 10.1111/j.1365-313x.2009.04010.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Attempted infection of plants by pathogens elicits a complex defensive response. In many non-host and incompatible host interactions it includes the induction of defence-associated genes and a form of localized cell death (LCD), purportedly designed to restrict pathogen advance, collectively known as the hypersensitive response (HR). It is preceded by an oxidative burst, generating reactive oxygen species (ROS) that are proposed to cue subsequent deployment of the HR, although neither the origin nor the precise role played by ROS in the execution of this response are completely understood. We used tobacco plants expressing cyanobacterial flavodoxin to address these questions. Flavodoxin is an electron shuttle present in prokaryotes and algae that, when expressed in chloroplasts, specifically prevents ROS formation in plastids during abiotic stress episodes. Infiltration of tobacco wild-type leaves with high titres of Xanthomonas campestris pv. vesicatoria (Xcv), a non-host pathogen, resulted in ROS accumulation in chloroplasts, followed by the appearance of localized lesions typical of the HR. In contrast, chloroplast ROS build-up and LCD were significantly reduced in Xcv-inoculated plants expressing plastid-targeted flavodoxin. Metabolic routes normally inhibited by pathogens were protected in the transformants, whereas other aspects of the HR, including the induction of defence-associated genes and synthesis of salicylic and jasmonic acid, proceeded as in inoculated wild-type plants. Therefore, ROS generated in chloroplasts during this non-host interaction are essential for the progress of LCD, but do not contribute to the induction of pathogenesis-related genes or other signalling components of the response.
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Affiliation(s)
- Matias D Zurbriggen
- Instituto de Biología Molecular y Celular de Rosario (IBR, UNR/CONICET), División Biología Molecular, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
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Szu PH, Ruszczycky MW, Choi SH, Yan F, Liu HW. Characterization and mechanistic studies of DesII: a radical S-adenosyl-L-methionine enzyme involved in the biosynthesis of TDP-D-desosamine. J Am Chem Soc 2009; 131:14030-42. [PMID: 19746907 PMCID: PMC2780582 DOI: 10.1021/ja903354k] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
D-desosamine (1) is a 3-(N,N-dimethylamino)-3,4,6-trideoxyhexose found in a number of macrolide antibiotics including methymycin (2), neomethymycin (3), pikromycin (4), and narbomycin (5) produced by Streptomyces venezuelae . It plays an essential role in conferring biological activities to its parent aglycones. Previous genetic and biochemical studies of the biosynthesis of desosamine in S. venezuelae showed that the conversion of TDP-4-amino-4,6-dideoxy-D-glucose (8) to TDP-3-keto-4,6-dideoxy-D-glucose (9) is catalyzed by DesII, which is a member of the radical S-adenosyl-L-methionine (SAM) enzyme superfamily. Here, we report the purification and reconstitution of His(6)-tagged DesII, characterization of its [4Fe-4S] cluster using UV-vis and EPR spectroscopies, and the capability of flavodoxin, flavodoxin reductase, and NADPH to reduce the [4Fe-4S](2+) cluster. Also included are a steady-state kinetic analysis of DesII-catalyzed reaction and an investigation of the substrate flexibility of DesII. Studies of deuterium incorporation into SAM using TDP-[3-(2)H]-4-amino-4,6-dideoxy-D-glucose as the substrate provides strong evidence for direct hydrogen atom transfer to a 5'-deoxyadenosyl radical in the catalytic cycle. The fact that hydrogen atom abstraction occurs at C-3 also sheds light on the mechanism of this intriguing deamination reaction.
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Affiliation(s)
- Ping-Hui Szu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA
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Guelker M, Stagg L, Wittung-Stafshede P, Shamoo Y. Pseudosymmetry, high copy number and twinning complicate the structure determination of Desulfovibrio desulfuricans (ATCC 29577) flavodoxin. Acta Crystallogr D Biol Crystallogr 2009; 65:523-34. [PMID: 19465766 PMCID: PMC2685730 DOI: 10.1107/s0907444909010075] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Accepted: 03/18/2009] [Indexed: 11/10/2022]
Abstract
The crystal structure of oxidized flavodoxin from Desulfovibrio desulfuricans (ATCC 29577) was determined by molecular replacement in two crystal forms, P3(1)21 and P4(3), at 2.5 and 2.0 A resolution, respectively. Structure determination in space group P3(1)21 was challenging owing to the presence of pseudo-translational symmetry and a high copy number in the asymmetric unit (8). Initial phasing attempts in space group P3(1)21 by molecular replacement using a poor search model (46% identity) and multi-wavelength anomalous dispersion were unsuccessful. It was necessary to solve the structure in a second crystal form, space group P4(3), which was characterized by almost perfect twinning, in order to obtain a suitable search model for molecular replacement. This search model with complementary approaches to molecular replacement utilizing the pseudo-translational symmetry operators determined by analysis of the native Patterson map facilitated the selection and manual placement of molecules to generate an initial solution in the P3(1)21 crystal form. During the early stages of refinement, application of the appropriate twin law, (-h, -k, l), was required to converge to reasonable R-factor values despite the fact that in the final analysis the data were untwinned and the twin law could subsequently be removed. The approaches used in structure determination and refinement may be applicable to other crystal structures characterized by these complicating factors. The refined model shows flexibility of the flavin mononucleotide coordinating loops indicated by the isolation of two loop conformations and provides a starting point for the elucidation of the mechanism used for protein-partner recognition.
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Affiliation(s)
- Megan Guelker
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, MS-140, Houston, TX 77005, USA
| | - Loren Stagg
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, MS-140, Houston, TX 77005, USA
| | - Pernilla Wittung-Stafshede
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, MS-140, Houston, TX 77005, USA
- Department of Chemistry, Umeå University, 901 87 Umeå, Sweden
| | - Yousif Shamoo
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street, MS-140, Houston, TX 77005, USA
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Goñi G, Herguedas B, Hervás M, Peregrina JR, De la Rosa MA, Gómez-Moreno C, Navarro JA, Hermoso JA, Martínez-Júlvez M, Medina M. Flavodoxin: a compromise between efficiency and versatility in the electron transfer from Photosystem I to Ferredoxin-NADP(+) reductase. Biochim Biophys Acta 2008; 1787:144-54. [PMID: 19150326 DOI: 10.1016/j.bbabio.2008.12.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Revised: 12/01/2008] [Accepted: 12/09/2008] [Indexed: 11/18/2022]
Abstract
Under iron-deficient conditions Flavodoxin (Fld) replaces Ferredoxin in Anabaena as electron carrier from Photosystem I (PSI) to Ferredoxin-NADP(+) reductase (FNR). Several residues modulate the Fld interaction with FNR and PSI, but no one appears as specifically critical for efficient electron transfer (ET). Fld shows a strong dipole moment, with its negative end directed towards the flavin ring. The role of this dipole moment in the processes of interaction and ET with positively charged surfaces exhibited by PSI and FNR has been analysed by introducing single and multiple charge reversal mutations on the Fld surface. Our data confirm that in this system interactions do not rely on a precise complementary surface of the reacting molecules. In fact, they indicate that the initial orientation driven by the alignment of dipole moment of the Fld molecule with that of the partner contributes to the formation of a bunch of alternative binding modes competent for the efficient ET reaction. Additionally, the fact that Fld uses different interaction surfaces to dock to PSI and to FNR is confirmed.
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Affiliation(s)
- Guillermina Goñi
- Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, 50009-Zaragoza, Spain
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