951
|
Dharmaraja AT, Ravikumar G, Chakrapani H. Arylboronate Ester Based Diazeniumdiolates (BORO/NO), a Class of Hydrogen Peroxide Inducible Nitric Oxide (NO) Donors. Org Lett 2014; 16:2610-3. [DOI: 10.1021/ol5010643] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Allimuthu T. Dharmaraja
- Indian Institute of Science
Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India
| | - Govindan Ravikumar
- Indian Institute of Science
Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India
| | - Harinath Chakrapani
- Indian Institute of Science
Education and Research Pune, Dr. Homi Bhabha Road, Pashan, Pune 411 008, Maharashtra, India
| |
Collapse
|
952
|
Usselman RJ, Hill I, Singel DJ, Martino CF. Spin biochemistry modulates reactive oxygen species (ROS) production by radio frequency magnetic fields. PLoS One 2014; 9:e93065. [PMID: 24681944 PMCID: PMC3969378 DOI: 10.1371/journal.pone.0093065] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 02/28/2014] [Indexed: 01/24/2023] Open
Abstract
The effects of weak magnetic fields on the biological production of reactive oxygen species (ROS) from intracellular superoxide (O2•-) and extracellular hydrogen peroxide (H2O2) were investigated in vitro with rat pulmonary arterial smooth muscle cells (rPASMC). A decrease in O2•- and an increase in H2O2 concentrations were observed in the presence of a 7 MHz radio frequency (RF) at 10 μTRMS and static 45 μT magnetic fields. We propose that O2•- and H2O2 production in some metabolic processes occur through singlet-triplet modulation of semiquinone flavin (FADH•) enzymes and O2•- spin-correlated radical pairs. Spin-radical pair products are modulated by the 7 MHz RF magnetic fields that presumably decouple flavin hyperfine interactions during spin coherence. RF flavin hyperfine decoupling results in an increase of H2O2 singlet state products, which creates cellular oxidative stress and acts as a secondary messenger that affects cellular proliferation. This study demonstrates the interplay between O2•- and H2O2 production when influenced by RF magnetic fields and underscores the subtle effects of low-frequency magnetic fields on oxidative metabolism, ROS signaling, and cellular growth.
Collapse
Affiliation(s)
- Robert J. Usselman
- Electromagnetics Division, National Institute of Standards and Technology, Boulder, Colorado, United States of America
| | - Iain Hill
- Department of Mechanical Engineering, University of Nevada Reno, Reno, Nevada, United States of America
| | - David J. Singel
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, United States of America
| | - Carlos F. Martino
- Department of Mechanical Engineering, University of Nevada Reno, Reno, Nevada, United States of America
| |
Collapse
|
953
|
Chan SW. Establishment of chronic hepatitis C virus infection: Translational evasion of oxidative defence. World J Gastroenterol 2014; 20:2785-2800. [PMID: 24659872 PMCID: PMC3961964 DOI: 10.3748/wjg.v20.i11.2785] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 12/03/2013] [Accepted: 01/15/2014] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) causes a clinically important disease affecting 3% of the world population. HCV is a single-stranded, positive-sense RNA virus belonging to the genus Hepacivirus within the Flaviviridae family. The virus establishes a chronic infection in the face of an active host oxidative defence, thus adaptation to oxidative stress is key to virus survival. Being a small RNA virus with a limited genomic capacity, we speculate that HCV deploys a different strategy to evade host oxidative defence. Instead of counteracting oxidative stress, it utilizes oxidative stress to facilitate its own survival. Translation is the first step in the replication of a plus strand RNA virus so it would make sense if the virus can exploit the host oxidative defence in facilitating this very first step. This is particularly true when HCV utilizes an internal ribosome entry site element in translation, which is distinctive from that of cap-dependent translation of the vast majority of cellular genes, thus allowing selective translation of genes under conditions when global protein synthesis is compromised. Indeed, we were the first to show that HCV translation was stimulated by an important pro-oxidant-hydrogen peroxide in hepatocytes, suggesting that HCV is able to adapt to and utilize the host anti-viral response to facilitate its own translation thus allowing the virus to thrive under oxidative stress condition to establish chronicity. Understanding how HCV translation is regulated under oxidative stress condition will advance our knowledge on how HCV establishes chronicity. As chronicity is the initiator step in disease progression this will eventually lead to a better understanding of pathogenicity, which is particularly relevant to the development of anti-virals and improved treatments of HCV patients using anti-oxidants.
Collapse
|
954
|
Intracellular hydrogen peroxide and superoxide poison 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase, the first committed enzyme in the aromatic biosynthetic pathway of Escherichia coli. J Bacteriol 2014; 196:1980-91. [PMID: 24659765 DOI: 10.1128/jb.01573-14] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In Escherichia coli, aromatic compound biosynthesis is the process that has shown the greatest sensitivity to hydrogen peroxide stress. This pathway has long been recognized to be sensitive to superoxide as well, but the molecular target was unknown. Feeding experiments indicated that the bottleneck lies early in the pathway, and the suppressive effects of fur mutations and manganese supplementation suggested the involvement of a metalloprotein. The 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase (DAHP synthase) activity catalyzes the first step in the pathway, and it is provided by three isozymes known to rely upon a divalent metal. This activity progressively declined when cells were stressed with either oxidant. The purified enzyme was activated more strongly by ferrous iron than by other metals, and only this metalloform could be inactivated by hydrogen peroxide or superoxide. We infer that iron is the prosthetic metal in vivo. Both oxidants displace the iron atom from the enzyme. In peroxide-stressed cells, the enzyme accumulated as an apoprotein, potentially with an oxidized cysteine residue. In superoxide-stressed cells, the enzyme acquired a nonactivating zinc ion in its active site, an apparent consequence of the repeated ejection of iron. Manganese supplementation protected the activity in both cases, which matches the ability of manganese to metallate the enzyme and to provide substantial oxidant-resistant activity. DAHP synthase thus belongs to a family of mononuclear iron-containing enzymes that are disabled by oxidative stress. To date, all the intracellular injuries caused by physiological doses of these reactive oxygen species have arisen from the oxidation of reduced iron centers.
Collapse
|
955
|
Johnson GA, Ellis EA, Kim H, Muthukrishnan N, Snavely T, Pellois JP. Photoinduced membrane damage of E. coli and S. aureus by the photosensitizer-antimicrobial peptide conjugate eosin-(KLAKLAK)2. PLoS One 2014; 9:e91220. [PMID: 24608860 PMCID: PMC3946741 DOI: 10.1371/journal.pone.0091220] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 02/07/2014] [Indexed: 01/17/2023] Open
Abstract
Background/Objectives Upon irradiation with visible light, the photosensitizer-peptide conjugate eosin-(KLAKLAK)2 kills a broad spectrum of bacteria without damaging human cells. Eosin-(KLAKLAK)2 therefore represents an interesting lead compound for the treatment of local infection by photodynamic bacterial inactivation. The mechanisms of cellular killing by eosin-(KLAKLAK)2, however, remain unclear and this lack of knowledge hampers the development of optimized therapeutic agents. Herein, we investigate the localization of eosin-(KLAKLAK)2 in bacteria prior to light treatment and examine the molecular basis for the photodynamic activity of this conjugate. Methodology/Principal Findings By employing photooxidation of 3,3-diaminobenzidine (DAB), (scanning) transmission electron microscopy ((S)TEM), and energy dispersive X-ray spectroscopy (EDS) methodologies, eosin-(KLAKLAK)2 is visualized at the surface of E. coli and S. aureus prior to photodynamic irradiation. Subsequent irradiation leads to severe membrane damage. Consistent with these observations, eosin-(KLAKLAK)2 binds to liposomes of bacterial lipid composition and causes liposomal leakage upon irradiation. The eosin moiety of the conjugate mediates bacterial killing and lipid bilayer leakage by generating the reactive oxygen species singlet oxygen and superoxide. In contrast, the (KLAKLAK)2 moiety targets the photosensitizer to bacterial lipid bilayers. In addition, while (KLAKLAK)2 does not disrupt intact liposomes, the peptide accelerates the leakage of photo-oxidized liposomes. Conclusions/Significance Together, our results suggest that (KLAKLAK)2 promotes the binding of eosin Y to bacteria cell walls and lipid bilayers. Subsequent light irradiation results in membrane damage from the production of both Type I & II photodynamic products. Membrane damage by oxidation is then further aggravated by the (KLAKLAK)2 moiety and membrane lysis is accelerated by the peptide. These results therefore establish how photosensitizer and peptide act in synergy to achieve bacterial photo-inactivation. Learning how to exploit and optimize this synergy should lead to the development of future bacterial photoinactivation agents that are effective at low concentrations and at low light doses.
Collapse
Affiliation(s)
- Gregory A. Johnson
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - E. Ann Ellis
- Microscopy & Imaging Center, Texas A&M University, College Station, Texas, United States of America
| | - Hansoo Kim
- Microscopy & Imaging Center, Texas A&M University, College Station, Texas, United States of America
| | - Nandhini Muthukrishnan
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Thomas Snavely
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Jean-Philippe Pellois
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
| |
Collapse
|
956
|
Mai-Prochnow A, Murphy AB, McLean KM, Kong MG, Ostrikov KK. Atmospheric pressure plasmas: infection control and bacterial responses. Int J Antimicrob Agents 2014; 43:508-17. [PMID: 24637224 DOI: 10.1016/j.ijantimicag.2014.01.025] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/25/2014] [Accepted: 01/27/2014] [Indexed: 12/26/2022]
Abstract
Cold atmospheric pressure plasma (APP) is a recent, cutting-edge antimicrobial treatment. It has the potential to be used as an alternative to traditional treatments such as antibiotics and as a promoter of wound healing, making it a promising tool in a range of biomedical applications with particular importance for combating infections. A number of studies show very promising results for APP-mediated killing of bacteria, including removal of biofilms of pathogenic bacteria such as Pseudomonas aeruginosa. However, the mode of action of APP and the resulting bacterial response are not fully understood. Use of a variety of different plasma-generating devices, different types of plasma gases and different treatment modes makes it challenging to show reproducibility and transferability of results. This review considers some important studies in which APP was used as an antibacterial agent, and specifically those that elucidate its mode of action, with the aim of identifying common bacterial responses to APP exposure. The review has a particular emphasis on mechanisms of interactions of bacterial biofilms with APP.
Collapse
Affiliation(s)
- Anne Mai-Prochnow
- CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070, Australia.
| | - Anthony B Murphy
- CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070, Australia
| | - Keith M McLean
- CSIRO Materials Science and Engineering, Bayview Avenue, Clayton, VIC 3168, Australia
| | - Michael G Kong
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Suite 422, 4211 Monarch Way, Norfolk, VA 23529, USA
| | - Kostya Ken Ostrikov
- CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070, Australia
| |
Collapse
|
957
|
Gerber GK. The dynamic microbiome. FEBS Lett 2014; 588:4131-9. [PMID: 24583074 DOI: 10.1016/j.febslet.2014.02.037] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 02/19/2014] [Accepted: 02/19/2014] [Indexed: 12/20/2022]
Abstract
While our genomes are essentially static, our microbiomes are inherently dynamic. The microbial communities we harbor in our bodies change throughout our lives due to many factors, including maturation during childhood, alterations in our diets, travel, illnesses, and medical treatments. Moreover, there is mounting evidence that our microbiomes change us, by promoting health through their beneficial actions or by increasing our susceptibility to diseases through a process termed dysbiosis. Recent technological advances are enabling unprecedentedly detailed studies of the dynamics of the microbiota in animal models and human populations. This review will highlight key areas of investigation in the field, including establishment of the microbiota during early childhood, temporal variability of the microbiome in healthy adults, responses of the microbiota to intentional perturbations such as antibiotics and dietary changes, and prospective analyses linking changes in the microbiota to host disease status. Given the importance of computational methods in the field, this review will also discuss issues and pitfalls in the analysis of microbiome time-series data, and explore several promising new directions for mathematical model and algorithm development.
Collapse
Affiliation(s)
- Georg K Gerber
- Brigham and Women's Hospital and Harvard Medical School, Department of Pathology, Center for Clinical and Translational Metagenomics, 221 Longwood Avenue, EBRC 422B, Boston, MA 02115, United States.
| |
Collapse
|
958
|
Engineering Synechocystis PCC6803 for hydrogen production: influence on the tolerance to oxidative and sugar stresses. PLoS One 2014; 9:e89372. [PMID: 24586727 PMCID: PMC3933540 DOI: 10.1371/journal.pone.0089372] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 01/20/2014] [Indexed: 11/23/2022] Open
Abstract
In the prospect of engineering cyanobacteria for the biological photoproduction of hydrogen, we have studied the hydrogen production machine in the model unicellular strain Synechocystis PCC6803 through gene deletion, and overexpression (constitutive or controlled by the growth temperature). We demonstrate that the hydrogenase-encoding hoxEFUYH operon is dispensable to standard photoautotrophic growth in absence of stress, and it operates in cell defense against oxidative (H2O2) and sugar (glucose and glycerol) stresses. Furthermore, we showed that the simultaneous over-production of the proteins HoxEFUYH and HypABCDE (assembly of hydrogenase), combined to an increase in nickel availability, led to an approximately 20-fold increase in the level of active hydrogenase. These novel results and mutants have major implications for those interested in hydrogenase, hydrogen production and redox metabolism, and their connections with environmental conditions.
Collapse
|
959
|
Gray MJ, Wholey WY, Wagner NO, Cremers CM, Mueller-Schickert A, Hock NT, Krieger AG, Smith EM, Bender RA, Bardwell JCA, Jakob U. Polyphosphate is a primordial chaperone. Mol Cell 2014; 53:689-99. [PMID: 24560923 DOI: 10.1016/j.molcel.2014.01.012] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 12/10/2013] [Accepted: 01/16/2014] [Indexed: 11/29/2022]
Abstract
Composed of up to 1,000 phospho-anhydride bond-linked phosphate monomers, inorganic polyphosphate (polyP) is one of the most ancient, conserved, and enigmatic molecules in biology. Here we demonstrate that polyP functions as a hitherto unrecognized chaperone. We show that polyP stabilizes proteins in vivo, diminishes the need for other chaperone systems to survive proteotoxic stress conditions, and protects a wide variety of proteins against stress-induced unfolding and aggregation. In vitro studies reveal that polyP has protein-like chaperone qualities, binds to unfolding proteins with high affinity in an ATP-independent manner, and supports their productive refolding once nonstress conditions are restored. Our results uncover a universally important function for polyP and suggest that these long chains of inorganic phosphate may have served as one of nature's first chaperones, a role that continues to the present day.
Collapse
Affiliation(s)
- Michael J Gray
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Wei-Yun Wholey
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA; Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Nico O Wagner
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Claudia M Cremers
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Antje Mueller-Schickert
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA; Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Nathaniel T Hock
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Adam G Krieger
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Erica M Smith
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Robert A Bender
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - James C A Bardwell
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA; Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA; Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ursula Jakob
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA; Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA.
| |
Collapse
|
960
|
Hess WR, Berghoff BA, Wilde A, Steglich C, Klug G. Riboregulators and the role of Hfq in photosynthetic bacteria. RNA Biol 2014; 11:413-26. [PMID: 24651049 PMCID: PMC4152350 DOI: 10.4161/rna.28035] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 01/29/2014] [Indexed: 12/25/2022] Open
Abstract
Anoxygenic and oxygenic bacteria directly convert solar energy into biomass using photosynthesis. The formation and composition of photosynthetic complexes has to be tightly controlled in response to environmental conditions, as exposure to sunlight can be harmful due to the generation of reactive oxygen species and the damaging effects of UV irradiation. Therefore, photosynthetic bacteria are exposed to a particular set of regulatory challenges in addition to those that also affect other bacteria, requiring sophisticated regulatory systems. Indeed, hundreds of potential regulatory RNAs have been identified in photosynthetic model bacteria as well as antisense RNAs (asRNAs) of up to several kb in length that protect certain mRNAs from degradation. The trans-acting small non-coding RNAs (sRNAs), PcrZ and PsrR1, control pigment and photosystem biogenesis in Rhodobacter sphaeroides and cyanobacteria, respectively. The asRNAs IsrR and As1_flv4 act as negative regulators and the asRNAs PsbA2R and PsbA3R as positive effectors of photosynthesis gene expression in Synechocystis 6803.
Collapse
Affiliation(s)
- Wolfgang R Hess
- Faculty of Biology; Institute for Biology III; University of Freiburg; Freiburg, Germany
| | - Bork A Berghoff
- Institute for Microbiology and Molecular Biology; University of Giessen; Giessen, Germany
| | - Annegret Wilde
- Faculty of Biology; Institute for Biology III; University of Freiburg; Freiburg, Germany
| | - Claudia Steglich
- Faculty of Biology; Institute for Biology III; University of Freiburg; Freiburg, Germany
| | - Gabriele Klug
- Institute for Microbiology and Molecular Biology; University of Giessen; Giessen, Germany
| |
Collapse
|
961
|
The role of iron and reactive oxygen species in cell death. Nat Chem Biol 2014; 10:9-17. [PMID: 24346035 DOI: 10.1038/nchembio.1416] [Citation(s) in RCA: 1491] [Impact Index Per Article: 149.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 11/19/2013] [Indexed: 02/06/2023]
Abstract
The transition metal iron is essential for life, yet potentially toxic iron-catalyzed reactive oxygen species (ROS) are unavoidable in an oxygen-rich environment. Iron and ROS are increasingly recognized as important initiators and mediators of cell death in a variety of organisms and pathological situations. Here, we review recent discoveries regarding the mechanism by which iron and ROS participate in cell death. We describe the different roles of iron in triggering cell death, targets of iron-dependent ROS that mediate cell death and a new form of iron-dependent cell death termed ferroptosis. Recent advances in understanding the role of iron and ROS in cell death offer unexpected surprises and suggest new therapeutic avenues to treat cancer, organ damage and degenerative disease.
Collapse
|
962
|
Boronat S, Domènech A, Paulo E, Calvo IA, García-Santamarina S, García P, Encinar del Dedo J, Barcons A, Serrano E, Carmona M, Hidalgo E. Thiol-based H2O2 signalling in microbial systems. Redox Biol 2014; 2:395-9. [PMID: 24563858 PMCID: PMC3926117 DOI: 10.1016/j.redox.2014.01.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Accepted: 01/16/2014] [Indexed: 11/19/2022] Open
Abstract
Cysteine residues, and in particular their thiolate groups, react not only with reactive oxygen species but also with electrophiles and with reactive nitrogen species. Thus, cysteine oxidation has often been linked to the toxic effects of some of these reactive molecules. However, thiol-based switches are common in protein sensors of antioxidant cascades, in both prokaryotic and eukaryotic organisms. We will describe here three redox sensors, the transcription factors OxyR, Yap1 and Pap1, which respond by disulfide bond formation to hydrogen peroxide stress, focusing specially on the differences among the three peroxide-sensing mechanisms.
Collapse
|
963
|
PerR-regulated manganese ion uptake contributes to oxidative stress defense in an oral streptococcus. Appl Environ Microbiol 2014; 80:2351-9. [PMID: 24487543 DOI: 10.1128/aem.00064-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Metal homeostasis plays a critical role in antioxidative stress. Streptococcus oligofermentans, an oral commensal facultative anaerobe lacking catalase activity, produces and tolerates abundant H2O2, whereas Dpr (an Fe(2+)-chelating protein)-dependent H2O2 protection does not confer such high tolerance. Here, we report that inactivation of perR, a peroxide-responsive repressor that regulates zinc and iron homeostasis in Gram-positive bacteria, increased the survival of H2O2-pulsed S. oligofermentans 32-fold and elevated cellular manganese 4.5-fold. perR complementation recovered the wild-type phenotype. When grown in 0.1 to 0.25 mM MnCl2, S. oligofermentans increased survival after H2O2 stress 2.5- to 23-fold, and even greater survival was found for the perR mutant, indicating that PerR is involved in Mn(2+)-mediated H2O2 resistance in S. oligofermentans. Mutation of mntA could not be obtained in brain heart infusion (BHI) broth (containing ~0.4 μM Mn(2+)) unless it was supplemented with ≥2.5 μM MnCl2 and caused 82 to 95% reduction of the cellular Mn(2+) level, while mntABC overexpression increased cellular Mn(2+) 2.1- to 4.5-fold. Thus, MntABC was identified as a high-affinity Mn(2+) transporter in S. oligofermentans. mntA mutation reduced the survival of H2O2-pulsed S. oligofermentans 5.7-fold, while mntABC overexpression enhanced H2O2-challenged survival 12-fold, indicating that MntABC-mediated Mn(2+) uptake is pivotal to antioxidative stress in S. oligofermentans. perR mutation or H2O2 pulsing upregulated mntABC, while H2O2-induced upregulation diminished in the perR mutant. This suggests that perR represses mntABC expression but H2O2 can release the suppression. In conclusion, this work demonstrates that PerR regulates manganese homeostasis in S. oligofermentans, which is critical to H2O2 stress defenses and may be distributed across all oral streptococci lacking catalase.
Collapse
|
964
|
Lu H, Patil S, Keener K, Cullen P, Bourke P. Bacterial inactivation by high-voltage atmospheric cold plasma: influence of process parameters and effects on cell leakage and DNA. J Appl Microbiol 2014; 116:784-94. [DOI: 10.1111/jam.12426] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/15/2013] [Accepted: 12/16/2013] [Indexed: 11/26/2022]
Affiliation(s)
- H. Lu
- School of Food Science and Environmental Health; Dublin Institute of Technology; Dublin 1 Ireland
| | - S. Patil
- School of Food Science and Environmental Health; Dublin Institute of Technology; Dublin 1 Ireland
| | - K.M. Keener
- Nelson Hall of Food Science; Rm 3215, 745 Agriculture Mall DriveWest Lafayette; Purdue University; West Lafayette IN USA
| | - P.J. Cullen
- School of Food Science and Environmental Health; Dublin Institute of Technology; Dublin 1 Ireland
| | - P. Bourke
- School of Food Science and Environmental Health; Dublin Institute of Technology; Dublin 1 Ireland
| |
Collapse
|
965
|
Siedler S, Schendzielorz G, Binder S, Eggeling L, Bringer S, Bott M. SoxR as a single-cell biosensor for NADPH-consuming enzymes in Escherichia coli. ACS Synth Biol 2014; 3:41-7. [PMID: 24283989 DOI: 10.1021/sb400110j] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An ultra-high-throughput screening system for NADPH-dependent enzymes, such as stereospecific alcohol dehydrogenases, was established. It is based on the [2Fe-2S] cluster-containing transcriptional regulator SoxR of Escherichia coli that activates expression of soxS in the oxidized but not in the reduced state of the cluster. As SoxR is kept in its reduced state by NADPH-dependent reductases, an increased NADPH demand of the cell counteracts SoxR reduction and increases soxS expression. We have taken advantage of these properties by placing the eyfp gene under the control of the soxS promoter and analyzed the response of E. coli cells expressing an NADPH-dependent alcohol dehydrogenase from Lactobacillus brevis (LbAdh), which reduces methyl acetoacetate to (R)-methyl 3-hydroxybutyrate. Under suitable conditions, the specific fluorescence of the cells correlated with the substrate concentration added and with LbAdh enzyme activity, supporting the NADPH responsiveness of the sensor. These properties enabled sorting of single cells harboring wild-type LbAdh from those with lowered or without LbAdh activity by fluorescence-activated cell sorting (FACS). In a proof-of-principle application, the system was used successfully to screen a mutant LbAdh library for variants showing improved activity with the substrate 4-methyl-2-pentanone.
Collapse
Affiliation(s)
- Solvej Siedler
- IBG-1:
Biotechnology, Institute
of Bio- and Geosciences, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Georg Schendzielorz
- IBG-1:
Biotechnology, Institute
of Bio- and Geosciences, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Stephan Binder
- IBG-1:
Biotechnology, Institute
of Bio- and Geosciences, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Lothar Eggeling
- IBG-1:
Biotechnology, Institute
of Bio- and Geosciences, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Stephanie Bringer
- IBG-1:
Biotechnology, Institute
of Bio- and Geosciences, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Michael Bott
- IBG-1:
Biotechnology, Institute
of Bio- and Geosciences, Forschungszentrum Jülich, D-52425 Jülich, Germany
| |
Collapse
|
966
|
Kim E, Leverage WT, Liu Y, White IM, Bentley WE, Payne GF. Redox-capacitor to connect electrochemistry to redox-biology. Analyst 2014; 139:32-43. [DOI: 10.1039/c3an01632c] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
967
|
Angelé-Martínez C, Goodman C, Brumaghim J. Metal-mediated DNA damage and cell death: mechanisms, detection methods, and cellular consequences. Metallomics 2014; 6:1358-81. [DOI: 10.1039/c4mt00057a] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Metal ions cause various types of DNA damage by multiple mechanisms, and this damage is a primary cause of cell death and disease.
Collapse
Affiliation(s)
| | - Craig Goodman
- Department of Chemistry
- Clemson University
- Clemson, USA
| | | |
Collapse
|
968
|
Essential roles of iron superoxide dismutase in photoautotrophic growth of Synechocystis sp. PCC 6803 and heterogeneous expression of marine Synechococcus sp. CC9311 copper/zinc superoxide dismutase within its sodB knockdown mutant. Microbiology (Reading) 2014; 160:228-241. [DOI: 10.1099/mic.0.073080-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Synechocystis sp. PCC 6803 possesses only one sod gene, sodB, encoding iron superoxide dismutase (FeSOD). It could not be knocked out completely by direct insertion of the kanamycin resistance cassette. When the promoter of sodB in WT Synechocystis was replaced with the copper-regulated promoter PpetE, a completely segregated PpetE–sodB strain could be obtained. When this strain was cultured in copper-starved BG11 medium, the chlorophyll a content was greatly reduced, growth was seriously inhibited and the strain was nearly dead during the 8 days of growth, whilst the WT strain grew well under the same growth conditions. These results indicated that sodB was essential for photoautotrophic growth of Synechocystis. The reduction of sodB gene copies in the Synechocystis genome rendered the cells more sensitive to oxidative stress produced by methyl viologen and norflurazon. sodB still could not be knocked out completely after active expression of sodC (encoding Cu/ZnSOD) from Synechococcus sp. CC9311 in the neutral site slr0168 under the control of the psbAII promoter, which means the function of FeSOD could not be complemented completely by Cu/ZnSOD. Heterogeneously expressed sodC increased the oxidation and photoinhibition tolerance of the Synechocystis sodB knockdown mutant. Membrane fractionation followed by immunoblotting revealed that FeSOD was localized in the cytoplasm, and Cu/ZnSOD was localized in the soluble and thylakoid membrane fractions of the transformed Synechocystis. Cu/ZnSOD has a predicted N-terminal signal peptide, so it is probably a lumen protein. The different subcellular localization of these two SODs may have resulted in the failure of substitution of sodC for sodB.
Collapse
|
969
|
Marrakchi M, Liu X, Andreescu S. Oxidative stress and antibiotic resistance in bacterial pathogens: state of the art, methodologies, and future trends. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 806:483-98. [PMID: 24952198 DOI: 10.1007/978-3-319-06068-2_23] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Despite the significant advances of modern medicine and the availability of a wide variety of antibiotics for the treatment of microbial infections, there is an alarming increase of multiresistant bacterial pathogens. This chapter discusses the status of bacterial resistance mechanisms and the relationship with oxidative stress and provides an overview of the methods used to assess oxidative conditions and their contribution to the antibiotic resistance.
Collapse
Affiliation(s)
- Mouna Marrakchi
- Department of Chemistry and Biomolecular Science, Clarkson University, 8 Clarkson Ave, Potsdam, NY, 13699-5810, USA,
| | | | | |
Collapse
|
970
|
Dharmaraja AT, Chakrapani H. A Small Molecule for Controlled Generation of Reactive Oxygen Species (ROS). Org Lett 2013; 16:398-401. [DOI: 10.1021/ol403300a] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Allimuthu T. Dharmaraja
- Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road Pashan, Pune 411 008, Maharashtra, India
| | - Harinath Chakrapani
- Indian Institute of Science Education and Research Pune, Dr. Homi Bhabha Road Pashan, Pune 411 008, Maharashtra, India
| |
Collapse
|
971
|
Culture volume and vessel affect long-term survival, mutation frequency, and oxidative stress of Escherichia coli. Appl Environ Microbiol 2013; 80:1732-8. [PMID: 24375138 DOI: 10.1128/aem.03150-13] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Bacteria such as Escherichia coli are frequently studied during exponential- and stationary-phase growth. However, many strains can survive in long-term stationary phase (LTSP), without the addition of nutrients, from days to several years. During LTSP, cells experience a variety of stressors, including reactive oxidative species, nutrient depletion, and metabolic toxin buildup, that lead to physiological responses and changes in genetic stability. In this study, we monitored survival during LTSP, as well as reporters of genetic and physiological change, to determine how the physical environment affects E. coli during long-term batch culture. We demonstrate differences in yield during LTSP in cells incubated in LB medium in test tubes versus Erlenmeyer flasks, as well as growth in different volumes of medium. We determined that these differences are only partially due to differences in oxygen levels by incubating the cells in different volumes of media under anaerobic conditions. Since we hypothesized that differences in long-term survival are the result of changes in physiological outputs during the late log and early stationary phases, we monitored alkalization, mutation frequency, oxidative stress response, and glycation. Although initial cell yields are essentially equivalent under each condition tested, physiological responses vary greatly in response to culture environment. Incubation in lower-volume cultures leads to higher oxyR expression but lower mutation frequency and glycation levels, whereas incubation in high-volume cultures has the opposite effect. We show here that even under commonly used experimental conditions that are frequently treated as equivalent, the stresses experienced by cells can differ greatly, suggesting that culture vessel and incubation conditions should be carefully considered in the planning or analysis of experiments.
Collapse
|
972
|
Lisher JP, Giedroc DP. Manganese acquisition and homeostasis at the host-pathogen interface. Front Cell Infect Microbiol 2013; 3:91. [PMID: 24367765 PMCID: PMC3851752 DOI: 10.3389/fcimb.2013.00091] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 11/18/2013] [Indexed: 11/21/2022] Open
Abstract
Pathogenic bacteria acquire transition metals for cell viability and persistence of infection in competition with host nutritional defenses. The human host employs a variety of mechanisms to stress the invading pathogen with both cytotoxic metal ions and oxidative and nitrosative insults while withholding essential transition metals from the bacterium. For example, the S100 family protein calprotectin (CP) found in neutrophils is a calcium-activated chelator of extracellular Mn and Zn and is found in tissue abscesses at sites of infection by Staphylococcus aureus. In an adaptive response, bacteria have evolved systems to acquire the metals in the face of this competition while effluxing excess or toxic metals to maintain a bioavailability of transition metals that is consistent with a particular inorganic "fingerprint" under the prevailing conditions. This review highlights recent biological, chemical and structural studies focused on manganese (Mn) acquisition and homeostasis and connects this process to oxidative stress resistance and iron (Fe) availability that operates at the human host-pathogen interface.
Collapse
Affiliation(s)
- John P. Lisher
- Graduate Program in Biochemistry, Indiana UniversityBloomington, IN, USA
| | - David P. Giedroc
- Graduate Program in Biochemistry, Indiana UniversityBloomington, IN, USA
- Department of Chemistry, Indiana UniversityBloomington, IN, USA
| |
Collapse
|
973
|
Barakat R, Goubet I, Manon S, Berges T, Rosenfeld E. Unsuspected pyocyanin effect in yeast under anaerobiosis. Microbiologyopen 2013; 3:1-14. [PMID: 24307284 PMCID: PMC3937724 DOI: 10.1002/mbo3.142] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 10/24/2013] [Accepted: 10/28/2013] [Indexed: 11/28/2022] Open
Abstract
The blue–green phenazine, Pyocyanin (PYO), is a well-known virulence factor produced by Pseudomonas aeruginosa, notably during cystic fibrosis lung infections. It is toxic to both eukaryotic and bacterial cells and several mechanisms, including the induction of oxidative stress, have been postulated. However, the mechanism of PYO toxicity under the physiological conditions of oxygen limitation that are encountered by P. aeruginosa and by target organisms in vivo remains unclear. In this study, wild-type and mutant strains of the yeast Saccharomyces cerevisiae were used as an effective eukaryotic model to determine the toxicity of PYO (100–500 μmol/L) under key growth conditions. Under respiro-fermentative conditions (with glucose as substrate), WT strains and certain H2O2-hypersensitive strains showed a low-toxic response to PYO. Under respiratory conditions (with glycerol as substrate) all the strains tested were significantly more sensitive to PYO. Four antioxidants were tested but only N-acetylcysteine was capable of partially counteracting PYO toxicity. PYO did not appear to affect short-term respiratory O2 uptake, but it did seem to interfere with cyanide-poisoned mitochondria through a complex III-dependent mechanism. Therefore, a combination of oxidative stress and respiration disturbance could partly explain aerobic PYO toxicity. Surprisingly, the toxic effects of PYO were more significant under anaerobic conditions. More pronounced effects were observed in several strains including a ‘petite’ strain lacking mitochondrial DNA, strains with increased or decreased levels of ABC transporters, and strains deficient in DNA damage repair. Therefore, even though PYO is toxic for actively respiring cells, O2 may indirectly protect the cells from the higher anaerobic-linked toxicity of PYO. The increased sensitivity to PYO under anaerobic conditions is not unique to S. cerevisiae and was also observed in another yeast, Candida albicans.
Collapse
Affiliation(s)
- Rana Barakat
- Université de La Rochelle - CNRS - UMR 7266 - LIENSs - LIttoral ENvironnement et Sociétés - Team: Approches Moléculaires: Environnement, Santé - Microbial Physiology Group, Avenue Michel Crépeau, 17042, La Rochelle Cedex 1, France
| | | | | | | | | |
Collapse
|
974
|
Martínez-García E, Nikel PI, Chavarría M, de Lorenzo V. The metabolic cost of flagellar motion in Pseudomonas putida KT2440. Environ Microbiol 2013; 16:291-303. [PMID: 24148021 DOI: 10.1111/1462-2920.12309] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 10/16/2013] [Indexed: 01/24/2023]
Abstract
Although the flagellar machinery of environmental bacteria endows cells with a phenomenal survival device, it also consumes much of the metabolic currency necessary for fuelling such a vigorous nano-motor. The physiological cost of flagella-related functions of the soil bacterium Pseudomonas putida KT2440 was examined and quantified through the deletion of a ≈ 70 kb DNA segment of the genome (≈ 1.1%), which includes relevant structural and regulatory genes in this micro-organism. The resulting strain lacked the protruding polar cords that define flagella in the wild-type P. putida strain and was unable of any swimming motility while showing a significant change in surface hydrophobicity. However, these deficiencies were otherwise concomitant with clear physiological advantages: rapid adaptation of the deleted strain to both glycolytic and gluconeogenic carbon sources, increased energy charge and, most remarkably, improved tolerance to oxidative stress, reflecting an increased NADPH/NADP(+) ratio. These qualities improve the endurance of non-flagellated cells to the metabolic fatigue associated with rapid growth in rich medium. Thus, flagellar motility represents the archetypal tradeoff involved in acquiring environmental advantages at the cost of a considerable metabolic burden.
Collapse
Affiliation(s)
- Esteban Martínez-García
- Systems Biology Program, Centro Nacional de Biotecnología-CSIC, Campus de Cantoblanco, 28049, Madrid, Spain
| | | | | | | |
Collapse
|
975
|
Protection from oxidative stress relies mainly on derepression of OxyR-dependent KatB and Dps in Shewanella oneidensis. J Bacteriol 2013; 196:445-58. [PMID: 24214945 DOI: 10.1128/jb.01077-13] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shewanella thrives in redox-stratified environments where accumulation of H2O2 becomes inevitable because of the chemical oxidation of reduced metals, sulfur species, or organic molecules. As a research model, the representative species Shewanella oneidensis has been extensively studied for its response to various stresses. However, little progress has been made toward an understanding of the physiological and genetic responses of this bacterium to oxidative stress, which is critically relevant to its application as a dissimilatory metal-reducing bacterium. In this study, we systematically investigated the mechanism underlying the response to H2O2 at cellular, genomic, and molecular levels. Using transcriptional profiling, we found that S. oneidensis is hypersensitive to H2O2 in comparison with Escherichia coli, and well-conserved defense genes such as ahpCF, katB, katG, and dps appear to form the first line of defense, whereas iron-sulfur-protecting proteins may not play a significant role. Subsequent identification and characterization of an analogue of the E. coli oxyR gene revealed that S. oneidensis OxyR is the master regulator that mediates the bacterial response to H2O2-induced oxidative stress by directly repressing or activating the defense genes. The sensitivity of S. oneidensis to H2O2 is likely attributable to the lack of an inducible manganese import mechanism during stress. To cope with stress, major strategies that S. oneidensis adopts include rapid removal of the oxidant and restriction of intracellular iron concentrations, both of which are achieved predominantly by derepression of the katB and dps genes.
Collapse
|
976
|
Gennaris A, Collet JF. The 'captain of the men of death', Streptococcus pneumoniae, fights oxidative stress outside the 'city wall'. EMBO Mol Med 2013; 5:1798-800. [PMID: 24293314 PMCID: PMC3914527 DOI: 10.1002/emmm.201303482] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Alexandra Gennaris
- Welbio and de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | | |
Collapse
|
977
|
The fluoroquinolone levofloxacin triggers the transcriptional activation of iron transport genes that contribute to cell death in Streptococcus pneumoniae. Antimicrob Agents Chemother 2013; 58:247-57. [PMID: 24145547 DOI: 10.1128/aac.01706-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We studied the transcriptomic response of Streptococcus pneumoniae to levofloxacin (LVX) under conditions inhibiting topoisomerase IV but not gyrase. Although a complex transcriptomic response was observed, the most outstanding result was the upregulation of the genes of the fatDCEB operon, involved in iron (Fe(2+) and Fe(3+)) uptake, which were the only genes varying under every condition tested. Although the inhibition of topoisomerase IV by levofloxacin did not have a detectable effect in the level of global supercoiling, increases in general supercoiling and fatD transcription were observed after topoisomerase I inhibition, while the opposite was observed after gyrase inhibition with novobiocin. Since fatDCEB is located in a topological chromosomal domain downregulated by DNA relaxation, we studied the transcription of a copy of the 422-bp (including the Pfat promoter) region located upstream of fatDCEB fused to the cat reporter inserted into the chromosome 106 kb away from its native position: PfatfatD was upregulated in the presence of LVX in its native location, whereas no change was observed in the Pfatcat construction. Results suggest that topological changes are indeed involved in PfatfatDCE transcription. Upregulation of fatDCEB would lead to an increase of intracellular iron and, in turn, to the activation of the Fenton reaction and the increase of reactive oxygen species. In accordance, we observed an attenuation of levofloxacin lethality in iron-deficient media and in a strain lacking the gene coding for SpxB, the main source of hydrogen peroxide. In addition, we observed an increase of reactive oxygen species that contributed to levofloxacin lethality.
Collapse
|
978
|
Identification of crucial amino acids of bacterial Peptide deformylases affecting enzymatic activity in response to oxidative stress. J Bacteriol 2013; 196:90-9. [PMID: 24142250 DOI: 10.1128/jb.00916-13] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Peptide deformylase (PDF) is an essential bacterial metalloprotease involved in deformylation of N-formyl group from nascent polypeptide chains during protein synthesis. Iron-containing variants of this enzyme from Salmonella enterica serovar Typhimurium (sPDF) and Mycobacterium tuberculosis (mPDF), although inhibited by oxidizing agents like H2O2, exhibited strikingly different 50% inhibitory concentrations (IC50s) that ranged from nanomolar (sPDF) to millimolar (mPDF) levels. Furthermore, the metal dissociation rate was higher in sPDF than mPDF. We hypothesized that a restriction in entry of environmental oxygen or oxidizing agents into the active site of mPDF might be the cause for such discrepancies between two enzymes. Since the active-site residues of the two proteins are similar, we evaluated the role of the oxidation-prone noncatalytic residue(s) in the process. Amino acid sequence analysis revealed that Cys-130 of sPDF corresponds to Met-145 of mPDF and that they are away from the active sites. Swapping methionine with cysteine in mPDF, the M145C protein displayed a drastic decrease in the IC50 for H2O2 and an increased metal dissociation rate compared to the wild type. Matrix-assisted laser desorption ionization (MALDI) analysis of a trypsin-digested fragment containing Cys-145 of the M145C protein also indicated its increased susceptibility to oxidation. To incorporate residues identical to those of mPDF, we created a double mutant of sPDF (C130M-V63C) that showed increased IC50 for H2O2 compared to the wild type. Interestingly, the oxidation state of cysteines in C130M-V63C was unaffected during H2O2 treatment. Taken together, our results unambiguously established the critical role of noncatalytic cysteine/methionine for enzymatic sensitivity to H2O2 and, thus, for conferring behavioral distinction of bacterial PDFs under oxidative stress conditions.
Collapse
|
979
|
Photocatalytic antibacterial effects are maintained on resin-based TiO2 nanocomposites after cessation of UV irradiation. PLoS One 2013; 8:e75929. [PMID: 24146793 PMCID: PMC3798317 DOI: 10.1371/journal.pone.0075929] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 08/22/2013] [Indexed: 11/19/2022] Open
Abstract
Photocatalysis induced by TiO2 and UV light constitutes a decontamination and antibacterial strategy utilized in many applications including self-cleaning environmental surfaces, water and air treatment. The present work reveals that antibacterial effects induced by photocatalysis can be maintained even after the cessation of UV irradiation. We show that resin-based composites containing 20% TiO2 nanoparticles continue to provide a pronounced antibacterial effect against the pathogens Escherichia coli, Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus mutans and Enterococcus faecalis for up to two hours post UV. For biomaterials or implant coatings, where direct UV illumination is not feasible, a prolonged antibacterial effect after the cessation of the illumination would offer new unexplored treatment possibilities.
Collapse
|
980
|
Lisher JP, Higgins KA, Maroney MJ, Giedroc DP. Physical characterization of the manganese-sensing pneumococcal surface antigen repressor from Streptococcus pneumoniae. Biochemistry 2013; 52:7689-701. [PMID: 24067066 DOI: 10.1021/bi401132w] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Transition metals, including manganese, are required for the proper virulence and persistence of many pathogenic bacteria. In Streptococcus pneumoniae (Spn), manganese homeostasis is controlled by a high-affinity Mn(II) uptake complex, PsaBCA, and a constitutively expressed efflux transporter, MntE. psaBCA expression is transcriptionally regulated by the DtxR/MntR family metalloregulatory protein pneumococcal surface antigen repressor (PsaR) in Spn. Here, we present a comprehensive analysis of the metal and DNA binding properties of PsaR. PsaR is a homodimer in the absence and presence of metals and binds two manganese or zinc atoms per protomer (four per dimer) in two pairs of structurally distinct sites, termed site 1 and site 2. Site 1 is likely filled with Zn(II) in vivo (K(Zn1) ≥ 10¹³ M⁻¹; K(Mn1) ≈ 10⁸ M⁻¹). The Zn(II)-site 1 complex adopts a pentacoordinate geometry as determined by X-ray absorption spectroscopy containing a single cysteine and appears to be analogous to the Cd(II) site observed in Streptococcus gordonii ScaR. Site 1 is necessary but not sufficient for full positive allosteric activation of DNA operator binding by metals as measured by ΔGc, the allosteric coupling free energy, because site 1 mutants show an intermediate ΔGc. Site 2 is the primary regulatory site and governs specificity for Mn(II) over Zn(II) in PsaR, where ΔGc(Zn,Mn) >> ΔGc(Zn,Zn) despite the fact that Zn(II) binds site 2 with an affinity 40-fold higher than that of Mn(II); i.e., K(Zn2) > K(Mn2). Mutational studies reveal that Asp7 in site 2 is a critical ligand for Mn(II)-dependent allosteric activation of DNA binding. These findings are discussed in the context of other well-studied DtxR/MntR Mn(II)/Fe(II) metallorepressors.
Collapse
Affiliation(s)
- John P Lisher
- Department of Chemistry and ‡Interdisciplinary Graduate Program in Biochemistry, Indiana University , Bloomington, Indiana 47405-7102, United States
| | | | | | | |
Collapse
|
981
|
Parker BW, Schwessinger EA, Jakob U, Gray MJ. The RclR protein is a reactive chlorine-specific transcription factor in Escherichia coli. J Biol Chem 2013; 288:32574-32584. [PMID: 24078635 DOI: 10.1074/jbc.m113.503516] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Reactive chlorine species (RCS) such as hypochlorous acid are powerful antimicrobial oxidants. Used extensively for disinfection in household and industrial settings (i.e. as bleach), RCS are also naturally generated in high quantities during the innate immune response. Bacterial responses to RCS are complex and differ substantially from the well characterized responses to other physiologically relevant oxidants, like peroxide or superoxide. Several RCS-sensitive transcription factors have been identified in bacteria, but most of them respond to multiple stressors whose damaging effects overlap with those of RCS, including reactive oxygen species and electrophiles. We have now used in vivo genetic and in vitro biochemical methods to identify and demonstrate that Escherichia coli RclR (formerly YkgD) is a redox-regulated transcriptional activator of the AraC family, whose highly conserved cysteine residues are specifically sensitive to oxidation by RCS. Oxidation of these cysteines leads to strong, highly specific activation of expression of genes required for survival of RCS stress. These results demonstrate the existence of a widely conserved bacterial regulon devoted specifically to RCS resistance.
Collapse
Affiliation(s)
- Benjamin W Parker
- From the Department of Molecular, Cellular, and Developmental Biology
| | | | - Ursula Jakob
- From the Department of Molecular, Cellular, and Developmental Biology; the Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan 48109.
| | - Michael J Gray
- From the Department of Molecular, Cellular, and Developmental Biology.
| |
Collapse
|
982
|
Turrientes MC, Baquero F, Levin BR, Martínez JL, Ripoll A, González-Alba JM, Tobes R, Manrique M, Baquero MR, Rodríguez-Domínguez MJ, Cantón R, Galán JC. Normal mutation rate variants arise in a Mutator (Mut S) Escherichia coli population. PLoS One 2013; 8:e72963. [PMID: 24069167 PMCID: PMC3771984 DOI: 10.1371/journal.pone.0072963] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 07/22/2013] [Indexed: 01/08/2023] Open
Abstract
The rate at which mutations are generated is central to the pace of evolution. Although this rate is remarkably similar amongst all cellular organisms, bacterial strains with mutation rates 100 fold greater than the modal rates of their species are commonly isolated from natural sources and emerge in experimental populations. Theoretical studies postulate and empirical studies teort the hypotheses that these “mutator” strains evolved in response to selection for elevated rates of generation of inherited variation that enable bacteria to adapt to novel and/or rapidly changing environments. Less clear are the conditions under which selection will favor reductions in mutation rates. Declines in rates of mutation for established populations of mutator bacteria are not anticipated if such changes are attributed to the costs of augmented rates of generation of deleterious mutations. Here we report experimental evidence of evolution towards reduced mutation rates in a clinical isolate of Escherichia coli with an hyper-mutable phenotype due a deletion in a mismatch repair gene, (ΔmutS). The emergence in a ΔmutS background of variants with mutation rates approaching those of the normal rates of strains carrying wild-type MutS was associated with increase in fitness with respect to ancestral strain. We postulate that such an increase in fitness could be attributed to the emergence of mechanisms driving a permanent “aerobic style of life”, the negative consequence of this behavior being regulated by the evolution of mechanisms protecting the cell against increased endogenous oxidative radicals involved in DNA damage, and thus reducing mutation rate. Gene expression assays and full sequencing of evolved mutator and normo-mutable variants supports the hypothesis. In conclusion, we postulate that the observed reductions in mutation rate are coincidental to, rather than, the selective force responsible for this evolution.
Collapse
Affiliation(s)
- María-Carmen Turrientes
- Department of Microbiology, Ramón y Cajal Institute for Health Research, Madrid, Spain
- Centro de Investigación Biomedica en Red de Epidemiología y Salud Pública, Carlos III Health Institute, Madrid, Spain
| | - Fernando Baquero
- Department of Microbiology, Ramón y Cajal Institute for Health Research, Madrid, Spain
- Centro de Investigación Biomedica en Red de Epidemiología y Salud Pública, Carlos III Health Institute, Madrid, Spain
- Joint Unit for Research in Antibiotic Resistance and Virulence, Madrid, Spain
- * E-mail: (FB); (JCG)
| | - Bruce R. Levin
- Department of Biology, Emory University, Atlanta Georgia, United States of America
| | - José-Luis Martínez
- Joint Unit for Research in Antibiotic Resistance and Virulence, Madrid, Spain
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Madrid, Spain
| | - Aida Ripoll
- Department of Microbiology, Ramón y Cajal Institute for Health Research, Madrid, Spain
- Centro de Investigación Biomedica en Red de Epidemiología y Salud Pública, Carlos III Health Institute, Madrid, Spain
| | - José-María González-Alba
- Department of Microbiology, Ramón y Cajal Institute for Health Research, Madrid, Spain
- Centro de Investigación Biomedica en Red de Epidemiología y Salud Pública, Carlos III Health Institute, Madrid, Spain
| | - Raquel Tobes
- Research Department, Era7 Bioinformatics, Granada, Spain
| | | | | | | | - Rafael Cantón
- Department of Microbiology, Ramón y Cajal Institute for Health Research, Madrid, Spain
- Faculty of Health Sciences, Alfonso X El Sabio University, Madrid, Spain
| | - Juan-Carlos Galán
- Department of Microbiology, Ramón y Cajal Institute for Health Research, Madrid, Spain
- Centro de Investigación Biomedica en Red de Epidemiología y Salud Pública, Carlos III Health Institute, Madrid, Spain
- Joint Unit for Research in Antibiotic Resistance and Virulence, Madrid, Spain
- * E-mail: (FB); (JCG)
| |
Collapse
|
983
|
How Escherichia coli tolerates profuse hydrogen peroxide formation by a catabolic pathway. J Bacteriol 2013; 195:4569-79. [PMID: 23913322 DOI: 10.1128/jb.00737-13] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
When Escherichia coli grows on conventional substrates, it continuously generates 10 to 15 μM/s intracellular H2O2 through the accidental autoxidation of redox enzymes. Dosimetric analyses indicate that scavenging enzymes barely keep this H2O2 below toxic levels. Therefore, it seemed potentially problematic that E. coli can synthesize a catabolic phenylethylamine oxidase that stoichiometrically generates H2O2. This study was undertaken to understand how E. coli tolerates the oxidative stress that must ensue. Measurements indicated that phenylethylamine-fed cells generate H2O2 at 30 times the rate of glucose-fed cells. Two tolerance mechanisms were identified. First, in enclosed laboratory cultures, growth on phenylethylamine triggered induction of the OxyR H2O2 stress response. Null mutants (ΔoxyR) that could not induce that response were unable to grow. This is the first demonstration that OxyR plays a role in protecting cells against endogenous H2O2. The critical element of the OxyR response was the induction of H2O2 scavenging enzymes, since mutants that lacked NADH peroxidase (Ahp) grew poorly, and those that additionally lacked catalase did not grow at all. Other OxyR-controlled genes were expendable. Second, phenylethylamine oxidase is an unusual catabolic enzyme in that it is localized in the periplasm. Calculations showed that when cells grow in an open environment, virtually all of the oxidase-generated H2O2 will diffuse across the outer membrane and be lost to the external world, rather than enter the cytoplasm where H2O2-sensitive enzymes are located. In this respect, the periplasmic compartmentalization of phenylethylamine oxidase serves the same purpose as the peroxisomal compartmentalization of oxidases in eukaryotic cells.
Collapse
|
984
|
Sánchez-Riego AM, López-Maury L, Florencio FJ. Glutaredoxins are essential for stress adaptation in the cyanobacterium Synechocystis sp. PCC 6803. FRONTIERS IN PLANT SCIENCE 2013; 4:428. [PMID: 24204369 PMCID: PMC3816324 DOI: 10.3389/fpls.2013.00428] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 10/10/2013] [Indexed: 05/10/2023]
Abstract
Glutaredoxins are small redox proteins able to reduce disulfides and mixed disulfides between GSH and proteins. Synechocystis sp. PCC 6803 contains three genes coding for glutaredoxins: ssr2061 (grxA) and slr1562 (grxB) code for dithiolic glutaredoxins while slr1846 (grxC) codes for a monothiolic glutaredoxin. We have analyzed the expression of these glutaredoxins in response to different stresses, such as high light, H2O2 and heat shock. Analysis of the mRNA levels showed that grxA is only induced by heat while grxC is repressed by heat shock and is induced by high light and H2O2. In contrast, grxB expression was maintained almost constant under all conditions. Analysis of GrxA and GrxC protein levels by western blot showed that GrxA increases in response to high light, heat or H2O2 while GrxC is only induced by high light and H2O2, in accordance with its mRNA levels. In addition, we have also generated mutants that have interrupted one, two, or three glutaredoxin genes. These mutants were viable and did not show any different phenotype from the WT under standard growth conditions. Nevertheless, analysis of these mutants under several stress conditions revealed that single grxA mutants grow slower after H2O2, heat and high light treatments, while mutants in grxB are indistinguishable from WT. grxC mutants were hypersensitive to treatments with H2O2, heat, high light and metals. A double grxAgrxC mutant was found to be even more sensitive to H2O2 than each corresponding single mutants. Surprisingly a mutation in grxB suppressed totally or partially the phenotypes of grxA and grxC mutants except the H2O2 sensitivity of the grxC mutant. This suggests that grxA and grxC participate in independent pathways while grxA and grxB participate in a common pathway for H2O2 resistance. The data presented here show that glutaredoxins are essential for stress adaptation in cyanobacteria, although their targets and mechanism of action remain unidentified.
Collapse
Affiliation(s)
| | | | - Francisco J. Florencio
- *Correspondence: Francisco J. Florencio, Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Av Americo Vespucio 49, E 41092 Seville, Spain e-mail:
| |
Collapse
|