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Miralles-Robledillo JM, Martínez-Espinosa RM, Pire C. Transcriptomic profiling of haloarchaeal denitrification through RNA-Seq analysis. Appl Environ Microbiol 2024; 90:e0057124. [PMID: 38814058 DOI: 10.1128/aem.00571-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 04/26/2024] [Indexed: 05/31/2024] Open
Abstract
Denitrification, a crucial biochemical pathway prevalent among haloarchaea in hypersaline ecosystems, has garnered considerable attention in recent years due to its ecological implications. Nevertheless, the underlying molecular mechanisms and genetic regulation governing this respiration/detoxification process in haloarchaea remain largely unexplored. In this study, RNA-sequencing was used to compare the transcriptomes of the haloarchaeon Haloferax mediterranei under oxic and denitrifying conditions, shedding light on the intricate metabolic alterations occurring within the cell, such as the accurate control of the metal homeostasis. Furthermore, the investigation identifies several genes encoding transcriptional regulators and potential accessory proteins with putative roles in denitrification. Among these are bacterioopsin-like transcriptional activators, proteins harboring a domain of unknown function (DUF2249), and cyanoglobin. In addition, the study delves into the genetic regulation of denitrification, finding a regulatory motif within promoter regions that activates numerous denitrification-related genes. This research serves as a starting point for future molecular biology studies in haloarchaea, offering a promising avenue to unravel the intricate mechanisms governing haloarchaeal denitrification, a pathway of paramount ecological importance.IMPORTANCEDenitrification, a fundamental process within the nitrogen cycle, has been subject to extensive investigation due to its close association with anthropogenic activities, and its contribution to the global warming issue, mainly through the release of N2O emissions. Although our comprehension of denitrification and its implications is generally well established, most studies have been conducted in non-extreme environments with mesophilic microorganisms. Consequently, there is a significant knowledge gap concerning extremophilic denitrifiers, particularly those inhabiting hypersaline environments. The significance of this research was to delve into the process of haloarchaeal denitrification, utilizing the complete denitrifier haloarchaeon Haloferax mediterranei as a model organism. This research led to the analysis of the metabolic state of this microorganism under denitrifying conditions and the identification of regulatory signals and genes encoding proteins potentially involved in this pathway, serving as a valuable resource for future molecular studies.
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Affiliation(s)
- Jose María Miralles-Robledillo
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
| | - Rosa María Martínez-Espinosa
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
- Multidisciplinary Institute for Environmental Studies "Ramón Margalef", University of Alicante, Alicante, Spain
| | - Carmen Pire
- Biochemistry, Molecular Biology, Edaphology and Agricultural Chemistry Department, Faculty of Sciences, Universitat d'Alacant, Alicante, Spain
- Multidisciplinary Institute for Environmental Studies "Ramón Margalef", University of Alicante, Alicante, Spain
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2
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Lê HG, Kim W, Kang JM, Võ TC, Yoo WG, Cheong H, Na BK. The anti-amoebic activity of Pinus densiflora leaf extract against the brain-eating amoeba Naegleria fowleri. PARASITES, HOSTS AND DISEASES 2024; 62:169-179. [PMID: 38835258 DOI: 10.3347/phd.23103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 02/14/2024] [Indexed: 06/06/2024]
Abstract
Naegleria fowleri invades the brain and causes a fatal primary amoebic meningoencephalitis (PAM). Despite its high mortality rate of approximately 97%, an effective therapeutic drug for PAM has not been developed. Approaches with miltefosine, amphotericin B, and other antimicrobials have been clinically attempted to treat PAM, but their therapeutic efficacy remains unclear. The development of an effective and safe therapeutic drug for PAM is urgently needed. In this study, we investigated the anti-amoebic activity of Pinus densiflora leaf extract (PLE) against N. fowleri. PLE induced significant morphological changes in N. fowleri trophozoites, resulting in the death of the amoeba. The IC50 of PLE on N. fowleri was 62.3±0.95 μg/ml. Alternatively, PLE did not significantly affect the viability of the rat glial cell line C6. Transcriptome analysis revealed differentially expressed genes (DEGs) between PLE-treated and non-treated amoebae. A total of 5,846 DEGs were identified, of which 2,189 were upregulated, and 3,657 were downregulated in the PLE-treated amoebae. The DEGs were categorized into biological process (1,742 genes), cellular component (1,237 genes), and molecular function (846 genes) based on the gene ontology analysis, indicating that PLE may have dramatically altered the biological and cellular functions of the amoeba and contributed to their death. These results suggest that PLE has anti-N. fowleri activity and may be considered as a potential candidate for the development of therapeutic drugs for PAM. It may also be used as a supplement compound to enhance the therapeutic efficacy of drugs currently used to treat PAM.
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Affiliation(s)
- Hương Giang Lê
- Department of Parasitology and Tropical Medicine, Institute of Health Science, Gyeongsang National University College of Medicine, Jinju 52727, Korea
- Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea
| | - Woong Kim
- Department of Biomedical Science, Chosun University, Gwangju 61453, Korea
- Institute of Well-Aging Medicare, Chosun University, Gwangju 61452, Korea
| | - Jung-Mi Kang
- Department of Parasitology and Tropical Medicine, Institute of Health Science, Gyeongsang National University College of Medicine, Jinju 52727, Korea
| | - Tuấn Cường Võ
- Department of Parasitology and Tropical Medicine, Institute of Health Science, Gyeongsang National University College of Medicine, Jinju 52727, Korea
- Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea
| | - Won Gi Yoo
- Department of Parasitology and Tropical Medicine, Institute of Health Science, Gyeongsang National University College of Medicine, Jinju 52727, Korea
- Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea
| | - Hyeonsook Cheong
- Department of Biomedical Science, Chosun University, Gwangju 61453, Korea
| | - Byoung-Kuk Na
- Department of Parasitology and Tropical Medicine, Institute of Health Science, Gyeongsang National University College of Medicine, Jinju 52727, Korea
- Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea
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Li JL, Li H, Zhao JJ, Yang P, Xiang X, Wei SY, Wang T, Shi YJ, Huang J, He F. Genome-wide identification and characterization of the RZFP gene family and analysis of its expression pattern under stress in Populus trichocarpa. Int J Biol Macromol 2024; 255:128108. [PMID: 37979769 DOI: 10.1016/j.ijbiomac.2023.128108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/11/2023] [Accepted: 11/13/2023] [Indexed: 11/20/2023]
Abstract
Forest trees face many abiotic stressors during their lifetime, including drought, heavy metals, high salinity, and chills, affecting their quality and yield. The RING-type ubiquitin ligase E3 is an invaluable component of the ubiquitin-proteasome system (UPS) and participates in plant growth and environmental interactions. Interestingly, only a few studies have explored the RING ZINC FINGER PROTEIN (RZFP) gene family. This study identified eight PtrRZFPs genes in the Populus genome, and their molecular features were analyzed. Gene structure analysis revealed that all PtrRZFPs genes contained >10 introns. Evolutionarily, the RZFPs were separated into four categories, and segmental replication events facilitated their amplification. Notably, many stress-related elements have been identified in the promoters of PtrRZFPs using Cis-acting element analysis. Moreover, some PtrRZFPs were significantly induced by drought and sorbitol, revealing their potential roles in regulating stress responses. Particularly, overexpression of the PtrRZFP1 gene in poplars conferred excellent drought tolerance; however, PtrRZFP1 knockdown plants were drought-sensitive. We identified the potential upstream transcription factors of PtrRZFPs and revealed the possible biological functions of RZFP1/4/7 in resisting osmotic and salt stress, laying the foundation for subsequent biological function studies and providing genetic resources for genetic engineering breeding for drought resistance in forest trees. This study offers crucial information for the further exploration of the functions of RZFPs in poplars.
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Affiliation(s)
- Jun-Lin Li
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China
| | - Hao Li
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China
| | - Jiu-Jiu Zhao
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China
| | - Peng Yang
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China
| | - Xiang Xiang
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China
| | - Shu-Ying Wei
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China
| | - Ting Wang
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China
| | - Yu-Jie Shi
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China
| | - Jinliang Huang
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China
| | - Fang He
- National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River & Forestry Ecological Engineering in the Upper Reaches of the Yangtze River Key Laboratory of Sichuan Province, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China.
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Soares NR, Huguet-Tapia JC, Guan D, Clark CA, Yang KT, Kluchka OR, Thombal RS, Kartika R, Badger JH, Pettis GS. Comparative genomics of the niche-specific plant pathogen Streptomyces ipomoeae reveal novel genome content and organization. Appl Environ Microbiol 2023; 89:e0030823. [PMID: 38009923 PMCID: PMC10734452 DOI: 10.1128/aem.00308-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 09/28/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE While most plant-pathogenic Streptomyces species cause scab disease on a variety of plant hosts, Streptomyces ipomoeae is the sole causative agent of soil rot disease of sweet potato and closely related plant species. Here, genome sequencing of virulent and avirulent S. ipomoeae strains coupled with comparative genomic analyses has identified genome content and organization features unique to this streptomycete plant pathogen. The results here will enable future research into the mechanisms used by S. ipomoeae to cause disease and to persist in its niche environment.
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Affiliation(s)
- Natasha R. Soares
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | | | - Dongli Guan
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Christopher A. Clark
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
| | - Kuei-Ting Yang
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Olivia R. Kluchka
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Raju S. Thombal
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Rendy Kartika
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Jonathan H. Badger
- Laboratory of Integrative Cancer Immunology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Gregg S. Pettis
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
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Poptic AL, Klinger JK, Carter SL, Moore CE, Zhang S. Nitrite Formation at a Diiron Dinitrosyl Complex. J Am Chem Soc 2023; 145:22993-22999. [PMID: 37815989 DOI: 10.1021/jacs.3c05155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
Pathogenic bacteria employ iron-containing enzymes to detoxify nitric oxide (NO•) produced by mammals as part of their immune response. Two classes of diiron proteins, flavodiiron nitric oxide reductases (FNORs) and the hemerythrin-like proteins from mycobacteria (HLPs), are upregulated in bacteria in response to an increased local NO• concentration. While FNORs reduce NO• to nitrous oxide (N2O), the HLPs have been found to either reduce nitrite to NO• (YtfE), or oxidize NO• to nitrite (Mka-HLP). Various structural and functional models of the diiron site in FNORs have been developed over the years. However, the NO• oxidation reactivity of Mka-HLP has yet to be replicated with a synthetic complex. Compared to the FNORs, the coordination environment of the diiron site in Mka-HLP contains one less carboxylate ligand and, therefore, is expected to be more electron-poor. Herein, we synthesized a new diiron complex that models the electron-poor coordination environment of the Mka-HLP diiron site. The diferrous precursor FeIIFeII reacts with NO• to form a diiron dinitrosyl species ({FeNO}72), which is in equilibrium with a mononitrosyl diiron species (FeII{FeNO}7) in solution. Both complexes can be isolated and fully characterized. However, only oxidation of {FeNO}72 produced nitrite in high yield (71%). Our study provides the first model that reproduces the NO• oxidase reactivity of Mka-HLP and suggests intermediacy of an {FeNO}6/{FeNO}7 species.
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Affiliation(s)
- Anna L Poptic
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio43210, United States
| | - Jeffrey K Klinger
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio43210, United States
| | - Samantha L Carter
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio43210, United States
| | - Curtis E Moore
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio43210, United States
| | - Shiyu Zhang
- Department of Chemistry & Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio43210, United States
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6
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Dobesova M, Kolackova M, Pencik O, Capal P, Chaloupsky P, Svec P, Ridoskova A, Motola M, Cicmancova V, Sopha H, Macak JM, Richtera L, Adam V, Huska D. Transcriptomic hallmarks of in vitro TiO 2 nanotubes toxicity in Chlamydomonas reinhardtii. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2023; 256:106419. [PMID: 36807021 DOI: 10.1016/j.aquatox.2023.106419] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
Recently, more accessible transcriptomic approaches have provided a new and deeper understanding of environmental toxicity. The present study focuses on the transcriptomic profiles of green microalgae Chlamydomonas reinhardtii exposed to new industrially promising material, TiO2 nanotubes (NTs), as an example of a widely used one-dimensional nanomaterial. The first algal in vitro assay included 2.5 and 7.5 mg/L TiO2 NTs, resulting in a dose-dependent negative effect on biological endpoints. At a working concentration of 7.5 mg/L, RNA-sequencing showed a mainly negative effect on the cells. In summary, the results indicated metabolic disruption, such as ATP loss, damage to mitochondria and chloroplasts, loss of solutes due to permeated membranes, and cell wall damage. Moreover, apoptosis-induced transcripts were detected. Interestingly, reactivation of transposons was observed. In signalling and transcription pathways, including chromatin remodelling and locking, the annotated genes were downregulated.
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Affiliation(s)
- Marketa Dobesova
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 613 00, Brno, Czech Republic
| | - Martina Kolackova
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 613 00, Brno, Czech Republic
| | - Ondrej Pencik
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 613 00, Brno, Czech Republic
| | - Petr Capal
- Institute of Experimental Botany, Centre of the Region Hana for Biotechnological and Agricultural Research, Slechtitelu 241/27, 783 71, Olomouc, Czech Republic
| | - Pavel Chaloupsky
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 613 00, Brno, Czech Republic
| | - Pavel Svec
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 613 00, Brno, Czech Republic; Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic
| | - Andrea Ridoskova
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 613 00, Brno, Czech Republic
| | - Martin Motola
- Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 530 02 Pardubice, Czech Republic
| | - Veronika Cicmancova
- Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic; Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 530 02 Pardubice, Czech Republic
| | - Hanna Sopha
- Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic; Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 530 02 Pardubice, Czech Republic
| | - Jan M Macak
- Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic; Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 530 02 Pardubice, Czech Republic
| | - Lukas Richtera
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 613 00, Brno, Czech Republic; Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic
| | - Vojtech Adam
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 613 00, Brno, Czech Republic
| | - Dalibor Huska
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 613 00, Brno, Czech Republic.
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Ximinies AD, Dou Y, Mishra A, Zhang K, Deivanayagam C, Wang C, Fletcher HM. The Oxidative Stress-Induced Hypothetical Protein PG_0686 in Porphyromonas gingivalis W83 Is a Novel Diguanylate Cyclase. Microbiol Spectr 2023; 11:e0441122. [PMID: 36719196 PMCID: PMC10101095 DOI: 10.1128/spectrum.04411-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 01/06/2023] [Indexed: 02/01/2023] Open
Abstract
The survival/adaptation of Porphyromonas gingivalis to the inflammatory environment of the periodontal pocket requires an ability to overcome oxidative stress. Several functional classes of genes, depending on the severity and duration of the exposure, were induced in P. gingivalis under H2O2-induced oxidative stress. The PG_0686 gene was highly upregulated under prolonged oxidative stress. PG_0686, annotated as a hypothetical protein of unknown function, is a 60 kDa protein that carries several domains including hemerythrin, PAS10, and domain of unknown function (DUF)-1858. Although PG_0686 showed some relatedness to several diguanylate cyclases (DGCs), it is missing the classical conserved, active site sequence motif (GGD[/E]EF), commonly observed in other bacteria. PG_0686-related proteins are observed in other anaerobic bacterial species. The isogenic mutant P. gingivalis FLL361 (ΔPG_0686::ermF) showed increased sensitivity to H2O2, and decreased gingipain activity compared to the parental strain. Transcriptome analysis of P. gingivalis FLL361 showed the dysregulation of several gene clusters/operons, known oxidative stress resistance genes, and transcriptional regulators, including PG_2212, CdhR and PG_1181 that were upregulated under normal anaerobic conditions. The intracellular level of c-di-GMP in P. gingivalis FLL361 was significantly decreased compared to the parental strain. The purified recombinant PG_0686 (rPG_0686) protein catalyzed the formation of c-di-GMP from GTP. Collectively, our data suggest a global regulatory property for PG_0686 that may be part of an unconventional second messenger signaling system in P. gingivalis. Moreover, it may coordinately regulate a pathway(s) vital for protection against environmental stress, and is significant in the pathogenicity of P. gingivalis and other anaerobes. IMPORTANCE Porphyromonas gingivalis is an important etiological agent in periodontitis and other systemic diseases. There is still a gap in our understanding of the mechanisms that P. gingivalis uses to survive the inflammatory microenvironment of the periodontal pocket. The hypothetical PG_0686 gene was highly upregulated under prolonged oxidative stress. Although the tertiary structure of PG_0686 showed little relatedness to previously characterized diguanylate cyclases (DGCs), and does not contain the conserved GGD(/E)EF catalytic domain motif sequence, an ability to catalyze the formation of c-di-GMP from GTP is demonstrated. The second messenger pathway for c-di-GMP was previously predicted to be absent in P. gingivalis. PG_0686 paralogs are identified in other anaerobic bacteria. Thus, PG_0686 may represent a novel class of DGCs, which is yet to be characterized. In conclusion, we have shown, for the first time, evidence for the presence of c-di-GMP signaling with environmental stress protective function in P. gingivalis.
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Affiliation(s)
- Alexia D. Ximinies
- Division of Microbiology & Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California, USA
| | - Yuetan Dou
- Division of Microbiology & Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California, USA
| | - Arunima Mishra
- Division of Microbiology & Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California, USA
| | - Kangling Zhang
- Department of Pharmacology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Champion Deivanayagam
- Department of Biochemistry and Molecular Genetics, University of Alabama, Birmingham, Alabama, USA
| | - Charles Wang
- Division of Microbiology & Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California, USA
| | - Hansel M. Fletcher
- Division of Microbiology & Molecular Genetics, School of Medicine, Loma Linda University, Loma Linda, California, USA
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Moubarak S, Rippers Y, Elghobashi-Meinhardt N, Mroginski MA. Structural and electronic properties of the active site of [ZnFe] SulE. Front Mol Biosci 2022; 9:945415. [DOI: 10.3389/fmolb.2022.945415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 09/12/2022] [Indexed: 11/13/2022] Open
Abstract
The function of the recently isolated sulerythrin (SulE) has been investigated using a combination of structural and electronic analyses based on quantum mechanical calculations. In the SulE structure of Fushinobu et al. (2003), isolated from a strictly aerobic archaeon, Sulfolobus tokadaii, a dioxygen-containing species was tentatively included at the active site during crystallographic refinement although the substrate specificity of SulE remains unclear. Studies have suggested that a structurally related enzyme, rubrerythrin, functions as a hydrogen peroxide reductase. Since SulE is a truncated version of rubrerythrin, the enzymes are hypothesized to function similarly. Hence, using available X-ray crystallography data (1.7 Å), we constructed various models of SulE containing a ZnII–Fe active site, differing in the nature of the substrate specificity (O2, H2O2), the oxidation level and the spin state of the iron ion, and the protonation states of the coordinating glutamate residues. Also, the substrate H2O2 is modeled in two possible configurations, differing in the orientation of the hydrogen atoms. Overall, the optimized geometries with an O2 substrate do not show good agreement with the experimentally resolved geometry. In contrast, excellent agreement between crystal structure arrangement and optimized geometries is achieved considering a H2O2 substrate and FeII in both spin states, when Glu92 is protonated. These results suggest that the dioxo species detected at the [ZnFe] active site of sulerythrin is H2O2, rather than an O2 molecule in agreement with experimental data indicating that only the diferrous oxidation state of the dimetal site in rubrerythrin reacts rapidly with H2O2. Based on our computations, we proposed a possible reaction pathway for substrate binding at the ZnFeII site of SulE with a H2O2 substrate. In this reaction pathway, Fe or another electron donor, such as NAD(P)H, catalyzes the reduction of H2O2 to water at the zinc–iron site.
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9
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Riese CN, Wittchen M, Jérôme V, Freitag R, Busche T, Kalinowski J, Schüler D. The transcriptomic landscape of Magnetospirillum gryphiswaldense during magnetosome biomineralization. BMC Genomics 2022; 23:699. [PMID: 36217140 PMCID: PMC9549626 DOI: 10.1186/s12864-022-08913-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 09/23/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND One of the most complex prokaryotic organelles are magnetosomes, which are formed by magnetotactic bacteria as sensors for navigation in the Earth's magnetic field. In the alphaproteobacterium Magnetospirillum gryphiswaldense magnetosomes consist of chains of magnetite crystals (Fe3O4) that under microoxic to anoxic conditions are biomineralized within membrane vesicles. To form such an intricate structure, the transcription of > 30 specific structural genes clustered within the genomic magnetosome island (MAI) has to be coordinated with the expression of an as-yet unknown number of auxiliary genes encoding several generic metabolic functions. However, their global regulation and transcriptional organization in response to anoxic conditions most favorable for magnetite biomineralization are still unclear. RESULTS Here, we compared transcriptional profiles of anaerobically grown magnetosome forming cells with those in which magnetosome biosynthesis has been suppressed by aerobic condition. Using whole transcriptome shotgun sequencing, we found that transcription of about 300 of the > 4300 genes was significantly enhanced during magnetosome formation. About 40 of the top upregulated genes are directly or indirectly linked to aerobic and anaerobic respiration (denitrification) or unknown functions. The mam and mms gene clusters, specifically controlling magnetosome biosynthesis, were highly transcribed, but constitutively expressed irrespective of the growth condition. By Cappable-sequencing, we show that the transcriptional complexity of both the MAI and the entire genome decreased under anaerobic conditions optimal for magnetosome formation. In addition, predominant promoter structures were highly similar to sigma factor σ70 dependent promoters in other Alphaproteobacteria. CONCLUSIONS Our transcriptome-wide analysis revealed that magnetite biomineralization relies on a complex interplay between generic metabolic processes such as aerobic and anaerobic respiration, cellular redox control, and the biosynthesis of specific magnetosome structures. In addition, we provide insights into global regulatory features that have remained uncharacterized in the widely studied model organism M. gryphiswaldense, including a comprehensive dataset of newly annotated transcription start sites and genome-wide operon detection as a community resource (GEO Series accession number GSE197098).
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Affiliation(s)
- Cornelius N Riese
- Department of Microbiology, University of Bayreuth, Bayreuth, Germany
| | - Manuel Wittchen
- Center for Biotechnology (CeBiTec), University of Bielefeld, Bielefeld, Germany
| | - Valérie Jérôme
- Chair for Process Biotechnology, University of Bayreuth, Bayreuth, Germany
| | - Ruth Freitag
- Chair for Process Biotechnology, University of Bayreuth, Bayreuth, Germany
| | - Tobias Busche
- Center for Biotechnology (CeBiTec), University of Bielefeld, Bielefeld, Germany
| | - Jörn Kalinowski
- Center for Biotechnology (CeBiTec), University of Bielefeld, Bielefeld, Germany
| | - Dirk Schüler
- Department of Microbiology, University of Bayreuth, Bayreuth, Germany.
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10
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Albert T, Moënne-Loccoz P. Spectroscopic Characterization of a Diferric Mycobacterial Hemerythrin-Like Protein with Unprecedented Reactivity toward Nitric Oxide. J Am Chem Soc 2022; 144:17611-17621. [PMID: 36099449 DOI: 10.1021/jacs.2c07113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hemerythrin-like proteins (HLPs) are broadly distributed across taxonomic groups and appear to play highly diverse functional roles in prokaryotes. Mycobacterial HLPs contribute to the survival of these pathogenic bacteria in mammalian macrophages, but their modes of action remain unclear. A recent crystallographic characterization of Mycobacterium kansasii HLP (Mka-HLP) revealed the unexpected presence of a tyrosine sidechain (Tyr54) near the coordination sphere of one of the two iron centers. Here, we show that Tyr54 is a true ligand to the Fe2(III) ion which, in conjunction with the presence of a μ-oxo group bridging the two iron(III), brings unique reactivity toward nitric oxide (NO). Monitoring the titration of Mka-HLP with NO by Fourier-transform infrared and electron paramagnetic resonance spectroscopies shows that both diferric and diferrous forms of Mka-HLP accumulate an uncoupled high-spin and low-spin {FeNO}7 pair. We assign the reactivity of the diferric protein to an initial radical reaction between NO and the μ-oxo bridge to form nitrite and a mixed-valent diiron center that can react further with NO. Amperometric measurements of NO consumption by Mka-HLP confirm that this reactivity can proceed at low micromolar concentrations of NO, before additional NO consumption, supporting a NO scavenging role for mycobacterial HLPs.
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Affiliation(s)
- Therese Albert
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Pierre Moënne-Loccoz
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States
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11
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Repair of Iron Center Proteins—A Different Class of Hemerythrin-like Proteins. Molecules 2022; 27:molecules27134051. [PMID: 35807291 PMCID: PMC9268430 DOI: 10.3390/molecules27134051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/14/2022] [Accepted: 06/17/2022] [Indexed: 01/27/2023] Open
Abstract
Repair of Iron Center proteins (RIC) form a family of di-iron proteins that are widely spread in the microbial world. RICs contain a binuclear nonheme iron site in a four-helix bundle fold, two basic features of hemerythrin-like proteins. In this work, we review the data on microbial RICs including how their genes are regulated and contribute to the survival of pathogenic bacteria. We gathered the currently available biochemical, spectroscopic and structural data on RICs with a particular focus on Escherichia coli RIC (also known as YtfE), which remains the best-studied protein with extensive biochemical characterization. Additionally, we present novel structural data for Escherichia coli YtfE harboring a di-manganese site and the protein’s affinity for this metal. The networking of protein interactions involving YtfE is also described and integrated into the proposed physiological role as an iron donor for reassembling of stress-damaged iron-sulfur centers.
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12
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Abstract
Subcellular compartmentalization is a defining feature of all cells. In prokaryotes, compartmentalization is generally achieved via protein-based strategies. The two main classes of microbial protein compartments are bacterial microcompartments and encapsulin nanocompartments. Encapsulins self-assemble into proteinaceous shells with diameters between 24 and 42 nm and are defined by the viral HK97-fold of their shell protein. Encapsulins have the ability to encapsulate dedicated cargo proteins, including ferritin-like proteins, peroxidases, and desulfurases. Encapsulation is mediated by targeting sequences present in all cargo proteins. Encapsulins are found in many bacterial and archaeal phyla and have been suggested to play roles in iron storage, stress resistance, sulfur metabolism, and natural product biosynthesis. Phylogenetic analyses indicate that they share a common ancestor with viral capsid proteins. Many pathogens encode encapsulins, and recent evidence suggests that they may contribute toward pathogenicity. The existing information on encapsulin structure, biochemistry, biological function, and biomedical relevance is reviewed here.
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Affiliation(s)
- Tobias W. Giessen
- Departments of Biomedical Engineering and Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan, USA
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13
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Full-Length Transcriptome Comparison Provides Novel Insights into the Molecular Basis of Adaptation to Different Ecological Niches of the Deep-Sea Hydrothermal Vent in Alvinocaridid Shrimps. DIVERSITY 2022. [DOI: 10.3390/d14050371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The deep-sea hydrothermal vent ecosystem is one of the extreme chemoautotrophic environments. Shinkaicaris leurokolos Kikuchi and Hashimoto, 2000, and Alvinocaris longirostris Kikuchi and Ohta, 1995, are typically co-distributed and closely related alvinocaridid shrimps in hydrothermal vent areas with different ecological niches, providing an excellent model for studying the adaptive evolution mechanism of animals in the extreme deep-sea hydrothermal vent environment. The shrimp S. leurokolos lives in close proximity to the chimney vent discharging high-temperature fluid, while A. longirostris inhabits the peripheral areas of hydrothermal vents. In this study, full-length transcriptomes of S. leurokolos and A. longirostris were generated using a combination of single-molecule real-time (SMRT) and Illumina RNA-seq technology. Expression analyses of the transcriptomes showed that among the top 30% of highly expressed genes of each species, more genes related to sulfide and heavy metal metabolism (sulfide: quinone oxidoreductase, SQR; persulfide dioxygenase, ETHE1; thiosulfate sulfurtransferase, TST, and ferritin, FRI) were specifically highly expressed in S. leurokolos, while genes involved in maintaining epibiotic bacteria or pathogen resistance (beta-1,3-glucan-binding protein, BGBP; endochitinase, CHIT; acidic mammalian chitinase, CHIA, and anti-lipopolysaccharide factors, ALPS) were highly expressed in A. longirostris. Gene family expansion analysis revealed that genes related to anti-oxidant metabolism (cytosolic manganese superoxide dismutase, SODM; glutathione S-transferase, GST, and glutathione peroxidase, GPX) and heat stress (heat shock cognate 70 kDa protein, HSP70 and heat shock 70 kDa protein cognate 4, HSP7D) underwent significant expansion in S. leurokolos, while CHIA and CHIT involved in pathogen resistance significantly expanded in A. longirostris. Finally, 66 positively selected genes (PSGs) were identified in the vent shrimp S. leurokolos. Most of the PSGs were involved in DNA repair, antioxidation, immune defense, and heat stress response, suggesting their function in the adaptive evolution of species inhabiting the extreme vent microhabitat. This study provides abundant genetic resources for deep-sea invertebrates, and is expected to lay the foundation for deep decipherment of the adaptive evolution mechanism of shrimps in a deep-sea chemosynthetic ecosystem based on further whole-genome comparison.
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14
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Crack JC, Balasiny BK, Bennett SP, Rolfe MD, Froes A, MacMillan F, Green J, Cole JA, Le Brun NE. The Di-Iron Protein YtfE Is a Nitric Oxide-Generating Nitrite Reductase Involved in the Management of Nitrosative Stress. J Am Chem Soc 2022; 144:7129-7145. [PMID: 35416044 PMCID: PMC9052748 DOI: 10.1021/jacs.1c12407] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
![]()
Previously characterized
nitrite reductases fall into three classes:
siroheme-containing enzymes (NirBD), cytochrome c hemoproteins (NrfA and NirS), and copper-containing enzymes (NirK).
We show here that the di-iron protein YtfE represents a physiologically
relevant new class of nitrite reductases. Several functions have been
previously proposed for YtfE, including donating iron for the repair
of iron–sulfur clusters that have been damaged by nitrosative
stress, releasing nitric oxide (NO) from nitrosylated iron, and reducing
NO to nitrous oxide (N2O). Here, in vivo reporter assays confirmed that Escherichia coli YtfE increased cytoplasmic NO production from nitrite. Spectroscopic
and mass spectrometric investigations revealed that the di-iron site
of YtfE exists in a mixture of forms, including nitrosylated and nitrite-bound,
when isolated from nitrite-supplemented, but not nitrate-supplemented,
cultures. Addition of nitrite to di-ferrous YtfE resulted in nitrosylated
YtfE and the release of NO. Kinetics of nitrite reduction were dependent
on the nature of the reductant; the lowest Km, measured for the di-ferrous form, was ∼90 μM,
well within the intracellular nitrite concentration range. The vicinal
di-cysteine motif, located in the N-terminal domain of YtfE, was shown
to function in the delivery of electrons to the di-iron center. Notably,
YtfE exhibited very low NO reductase activity and was only able to
act as an iron donor for reconstitution of apo-ferredoxin under conditions
that damaged its di-iron center. Thus, YtfE is a high-affinity, low-capacity
nitrite reductase that we propose functions to relieve nitrosative
stress by acting in combination with the co-regulated NO-consuming
enzymes Hmp and Hcp.
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Affiliation(s)
- Jason C Crack
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Basema K Balasiny
- Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Sophie P Bennett
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Matthew D Rolfe
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Afonso Froes
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Fraser MacMillan
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Jeffrey Green
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Jeffrey A Cole
- Institute of Microbiology and Infection and School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Nick E Le Brun
- Centre for Molecular and Structural Biochemistry, School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
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15
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Malych R, Füssy Z, Ženíšková K, Arbon D, Hampl V, Hrdý I, Sutak R. The response of Naegleria gruberi to oxidative stress. Metallomics 2022; 14:6527579. [PMID: 35150262 DOI: 10.1093/mtomcs/mfac009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 02/06/2022] [Indexed: 11/14/2022]
Abstract
Aerobic organisms require oxygen for respiration but must simultaneously cope with oxidative damages inherently linked with this molecule. Unicellular amoeboflagellates of the genus Naegleria, containing both free-living species and opportunistic parasite, thrive in aerobic environments. However, they are also known to maintain typical features of anaerobic organisms. Here, we describe the mechanisms of oxidative damage mitigation in Naegleria gruberi and focus on the molecular characteristics of three noncanonical proteins interacting with oxygen and its derived reactive forms. We show that this protist expresses hemerythrin, protoglobin and an aerobic-type rubrerythrin, with spectral properties characteristic of the cofactors they bind. We provide evidence that protoglobin and hemerythrin interact with oxygen in vitro and confirm the mitochondrial localization of rubrerythrin by immunolabeling. Our proteomic analysis and immunoblotting following heavy metal treatment revealed upregulation of hemerythrin, while rotenone treatment resulted in an increase in rubrerythrin protein levels together with vast upregulation of alternative oxidase. Our study provided new insights into the mechanisms employed by N. gruberi to cope with different types of oxidative stress and allowed us to propose specific roles for three unique and understudied proteins: hemerythrin, protoglobin and rubrerythrin.
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Affiliation(s)
- Ronald Malych
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Zoltán Füssy
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Kateřina Ženíšková
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Dominik Arbon
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Vladimír Hampl
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Ivan Hrdý
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Robert Sutak
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
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16
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Ma Z, Holland AA, Szlamkowicz I, Anagnostopoulos V, Caldas Nogueira ML, Caranto JD, Davidson VL. The hemerythrin-like diiron protein from Mycobacterium kansasii is a nitric oxide peroxidase. J Biol Chem 2022; 298:101696. [PMID: 35150744 PMCID: PMC8913304 DOI: 10.1016/j.jbc.2022.101696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 02/03/2022] [Accepted: 02/04/2022] [Indexed: 11/30/2022] Open
Abstract
The hemerythrin-like protein from Mycobacterium kansasii (Mka HLP) is a member of a distinct class of oxo-bridged diiron proteins that are found only in mycobacterial species that cause respiratory disorders in humans. Because it had been shown to exhibit weak catalase activity and a change in absorbance on exposure to nitric oxide (NO), the reactivity of Mka HLP toward NO was examined under a variety of conditions. Under anaerobic conditions, we found that NO was converted to nitrite (NO2−) via an intermediate, which absorbed light at 520 nm. Under aerobic conditions NO was converted to nitrate (NO3−). In each of these two cases, the maximum amount of nitrite or nitrate formed was at best stoichiometric with the concentration of Mka HLP. When incubated with NO and H2O2, we observed NO peroxidase activity yielding nitrite and water as reaction products. Steady-state kinetic analysis of NO consumption during this reaction yielded a Km for NO of 0.44 μM and a kcat/Km of 2.3 × 105 M−1s−1. This high affinity for NO is consistent with a physiological role for Mka HLP in deterring nitrosative stress. This is the first example of a peroxidase that uses an oxo-bridged diiron center and a rare example of a peroxidase utilizing NO as an electron donor and cosubstrate. This activity provides a mechanism by which the infectious Mycobacterium may combat against the cocktail of NO and superoxide (O2•−) generated by macrophages to defend against bacteria, as well as to produce NO2− to adapt to hypoxic conditions.
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Affiliation(s)
- Zhongxin Ma
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827 United States
| | - Ashley A Holland
- Department of Chemistry, University of Central Florida, 4111 Libra Drive, Room 255, Orlando, Florida 32816, United States
| | - Ilana Szlamkowicz
- Department of Chemistry, University of Central Florida, 4111 Libra Drive, Room 255, Orlando, Florida 32816, United States
| | - Vasileios Anagnostopoulos
- Department of Chemistry, University of Central Florida, 4111 Libra Drive, Room 255, Orlando, Florida 32816, United States
| | - Maria Luiza Caldas Nogueira
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827 United States
| | - Jonathan D Caranto
- Department of Chemistry, University of Central Florida, 4111 Libra Drive, Room 255, Orlando, Florida 32816, United States.
| | - Victor L Davidson
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827 United States.
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17
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Ruhl IA, Sheremet A, Furgason CC, Krause S, Bowers RM, Jarett JK, Tran TM, Grasby SE, Woyke T, Dunfield PF. GAL08, an Uncultivated Group of Acidobacteria, Is a Dominant Bacterial Clade in a Neutral Hot Spring. Front Microbiol 2022; 12:787651. [PMID: 35087491 PMCID: PMC8787282 DOI: 10.3389/fmicb.2021.787651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 11/29/2021] [Indexed: 11/28/2022] Open
Abstract
GAL08 are bacteria belonging to an uncultivated phylogenetic cluster within the phylum Acidobacteria. We detected a natural population of the GAL08 clade in sediment from a pH-neutral hot spring located in British Columbia, Canada. To shed light on the abundance and genomic potential of this clade, we collected and analyzed hot spring sediment samples over a temperature range of 24.2–79.8°C. Illumina sequencing of 16S rRNA gene amplicons and qPCR using a primer set developed specifically to detect the GAL08 16S rRNA gene revealed that absolute and relative abundances of GAL08 peaked at 65°C along three temperature gradients. Analysis of sediment collected over multiple years and locations revealed that the GAL08 group was consistently a dominant clade, comprising up to 29.2% of the microbial community based on relative read abundance and up to 4.7 × 105 16S rRNA gene copy numbers per gram of sediment based on qPCR. Using a medium quality threshold, 25 single amplified genomes (SAGs) representing these bacteria were generated from samples taken at 65 and 77°C, and seven metagenome-assembled genomes (MAGs) were reconstructed from samples collected at 45–77°C. Based on average nucleotide identity (ANI), these SAGs and MAGs represented three separate species, with an estimated average genome size of 3.17 Mb and GC content of 62.8%. Phylogenetic trees constructed from 16S rRNA gene sequences and a set of 56 concatenated phylogenetic marker genes both placed the three GAL08 bacteria as a distinct subgroup of the phylum Acidobacteria, representing a candidate order (Ca. Frugalibacteriales) within the class Blastocatellia. Metabolic reconstructions from genome data predicted a heterotrophic metabolism, with potential capability for aerobic respiration, as well as incomplete denitrification and fermentation. In laboratory cultivation efforts, GAL08 counts based on qPCR declined rapidly under atmospheric levels of oxygen but increased slightly at 1% (v/v) O2, suggesting a microaerophilic lifestyle.
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Affiliation(s)
- Ilona A Ruhl
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Andriy Sheremet
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Chantel C Furgason
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Susanne Krause
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Robert M Bowers
- U.S. Department of Energy Joint Genome Institute, Berkeley, CA, United States
| | - Jessica K Jarett
- U.S. Department of Energy Joint Genome Institute, Berkeley, CA, United States
| | - Triet M Tran
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Stephen E Grasby
- Department of Geoscience, University of Calgary, Calgary, AB, Canada.,Geological Survey of Canada, Calgary, AB, Canada
| | - Tanja Woyke
- U.S. Department of Energy Joint Genome Institute, Berkeley, CA, United States
| | - Peter F Dunfield
- Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
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18
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Alves SR, Santos RLSR, Fornaciari B, Colquhoun A, de Oliveira Silva D. A novel μ-oxo-diruthenium(III,III)-ibuprofen-(4-aminopyridine) chloride derived from the diruthenium(II,III)-ibuprofen paddlewheel metallodrug shows anticancer properties. J Inorg Biochem 2021; 225:111596. [PMID: 34601164 DOI: 10.1016/j.jinorgbio.2021.111596] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 08/24/2021] [Accepted: 08/28/2021] [Indexed: 10/20/2022]
Abstract
Diruthenium(II,III) metal-metal multiply bonded paddlewheel complexes bearing non-steroidal anti-inflammatory drugs are promising anticancer metallodrugs. The [Ru2(Ibp)4Cl] (Ibp, ibuprofenate anion from HIbp ibuprofen drug), free or encapsulated, shows anticancer activity against glioblastoma (in vitro, in vivo), and against human breast and prostate cancer cells. Herein we report the interaction of [Ru2(Ibp)4Cl] and of [Ru2(Ac)4(H2O)2]PF6 (Ac, acetate) with the 4-aminopyridine (4Apy) drug. The N-ligand was capable of cleaving the paddlewheel unit with oxidation of Ru2(II,III) to Ru2(III,III)O μ-oxo core in the ibuprofen complex while the acetate complex underwent axial substitution of water by 4Apy. Carefully designed synthetic and chromatographic methods succeeded in giving the novel [Ru2O(Ibp)2(4Apy)6]Cl2 metallodrug, the first diruthenium(III,III) μ-oxo having chloride as counterion. Characterization was performed by elemental analysis, mass spectrometry, thermogravimetric analysis, electronic absorption and vibrational spectroscopies, molar conductivity and cyclic voltammetry. Kinetic studies for the μ-oxo complex (in 50:50 v/v ethanol:water) suggested an aquation/complexation equilibrium in consecutive step reactions with the exchange of the two 4Apy trans to the μ-oxo bridge by water (aquation) and the back coordination of 4Apy in excess of the N-ligand (complexation). Trypan blue assays for the novel compound showed time- and dose- dependent antiproliferative effects (at 5-50 μmol L-1) and cytotoxicity (> 20 μmol L-1), and MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assays gave IC50 value of 7.6 ± 1.5 μmol L-1 (at 48 h, 1-20 μmol L-1) against U87MG human glioblastoma cells (aggressive brain glioma cancer) pointing the metallodrug as potential candidate for novel therapies in gliomas.
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Affiliation(s)
- Samara R Alves
- Laboratory for Synthetic and Structural Inorganic Chemistry - Bioinorganic and Metallodrugs, Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, B2T, 05508-000 São Paulo, SP, Brazil
| | - Rodrigo L S R Santos
- Laboratory for Synthetic and Structural Inorganic Chemistry - Bioinorganic and Metallodrugs, Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, B2T, 05508-000 São Paulo, SP, Brazil; Department of Exact and Technological Sciences, State University of Santa Cruz, Rod. Jorge Amado, Km 16, 45662-900 Ilhéus, BA, Brazil
| | - Bárbara Fornaciari
- Laboratory for Synthetic and Structural Inorganic Chemistry - Bioinorganic and Metallodrugs, Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, B2T, 05508-000 São Paulo, SP, Brazil
| | - Alison Colquhoun
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 1524, 05508-000 São Paulo, SP, Brazil
| | - Denise de Oliveira Silva
- Laboratory for Synthetic and Structural Inorganic Chemistry - Bioinorganic and Metallodrugs, Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, B2T, 05508-000 São Paulo, SP, Brazil.
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19
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Andreas MP, Giessen TW. Large-scale computational discovery and analysis of virus-derived microbial nanocompartments. Nat Commun 2021; 12:4748. [PMID: 34362927 PMCID: PMC8346489 DOI: 10.1038/s41467-021-25071-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/12/2021] [Indexed: 02/06/2023] Open
Abstract
Encapsulins are a class of microbial protein compartments defined by the viral HK97-fold of their capsid protein, self-assembly into icosahedral shells, and dedicated cargo loading mechanism for sequestering specific enzymes. Encapsulins are often misannotated and traditional sequence-based searches yield many false positive hits in the form of phage capsids. Here, we develop an integrated search strategy to carry out a large-scale computational analysis of prokaryotic genomes with the goal of discovering an exhaustive and curated set of all HK97-fold encapsulin-like systems. We find over 6,000 encapsulin-like systems in 31 bacterial and four archaeal phyla, including two novel encapsulin families. We formulate hypotheses about their potential biological functions and biomedical relevance, which range from natural product biosynthesis and stress resistance to carbon metabolism and anaerobic hydrogen production. An evolutionary analysis of encapsulins and related HK97-type virus families shows that they share a common ancestor, and we conclude that encapsulins likely evolved from HK97-type bacteriophages.
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Affiliation(s)
- Michael P Andreas
- Department of Biomedical Engineering, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Tobias W Giessen
- Department of Biomedical Engineering, University of Michigan Medical School, Ann Arbor, MI, USA.
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA.
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20
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Silva LSO, Matias PM, Romão CV, Saraiva LM. Structural Basis of RICs Iron Donation for Iron-Sulfur Cluster Biogenesis. Front Microbiol 2021; 12:670681. [PMID: 33995335 PMCID: PMC8117158 DOI: 10.3389/fmicb.2021.670681] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
Escherichia coli YtfE is a di-iron protein of the widespread Repair of Iron Centers proteins (RIC) family that has the capacity to donate iron, which is a crucial component of the biogenesis of the ubiquitous family of iron-sulfur proteins. In this work we identify in E. coli a previously unrecognized link between the YtfE protein and the major bacterial system for iron-sulfur cluster (ISC) assembly. We show that YtfE establishes protein-protein interactions with the scaffold IscU, where the transient cluster is formed, and the cysteine desulfurase IscS. Moreover, we found that promotion by YtfE of the formation of an Fe-S cluster in IscU requires two glutamates, E125 and E159 in YtfE. Both glutamates form part of the entrance of a protein channel in YtfE that links the di-iron center to the surface. In particular, E125 is crucial for the exit of iron, as a single mutation to leucine closes the channel rendering YtfE inactive for the build-up of Fe-S clusters. Hence, we provide evidence for the key role of RICs as bacterial iron donor proteins involved in the biogenesis of Fe-S clusters.
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Affiliation(s)
- Liliana S O Silva
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Pedro M Matias
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.,iBET, Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
| | - Célia V Romão
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Lígia M Saraiva
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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21
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Caldas Nogueira ML, Pastore AJ, Davidson VL. Diversity of structures and functions of oxo-bridged non-heme diiron proteins. Arch Biochem Biophys 2021; 705:108917. [PMID: 33991497 DOI: 10.1016/j.abb.2021.108917] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/04/2021] [Accepted: 05/06/2021] [Indexed: 02/07/2023]
Abstract
Oxo-bridged diiron proteins are a distinct class of non-heme iron proteins. Their active sites are composed of two irons that are coordinated by amino acid side chains, and a bridging oxygen that interacts with each iron. These proteins are members of the ferritin superfamily and share the structural feature of a four α-helix bundle that provides the residues that coordinate the irons. The different proteins also display a wide range of structures and functions. A prototype of this family is hemerythrin, which functions as an oxygen transporter. Several other hemerythrin-like proteins have been described with a diversity of functions including oxygen and iron sensing, and catalytic activities. Rubrerythrins react with hydrogen peroxide and rubrerythrin-like proteins possess a rubredoxin domain, in addition to the oxo-bridged diiron center. Other redox enzymes with oxo-bridged irons include flavodiiron proteins that act as O2 or NO reductases, ribonucleotide reductase and methane monooxygenase. Ferritins have an oxo-bridged diiron in the ferroxidase center of the protein, which plays a role in the iron storage function of these proteins. There are also bacterial ferritins that exhibit catalytic activities. The structures and functions of this broad class of oxo-bridged diiron proteins are described and compared in this review.
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Affiliation(s)
- Maria Luiza Caldas Nogueira
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32827, United States
| | - Anthony J Pastore
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32827, United States
| | - Victor L Davidson
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32827, United States.
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22
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Tsai RF, Lin NC, Kao TY, Kuo YH, Lo FC, Liaw WF, Chiang YW. Nitrosylation of the Diiron Core Mediated by the N Domain of YtfE. J Phys Chem Lett 2020; 11:8538-8542. [PMID: 32940468 DOI: 10.1021/acs.jpclett.0c02200] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The YtfE protein catalyzes the reduction of NO to N2O, protecting iron-sulfur clusters from nitrosylation. The structure of YtfE has a two-domain architecture, with a diiron-containing C-terminal domain linked to an N-terminal domain, in which the function of the latter is enigmatic. Here, by using electron spin resonance (ESR) spectroscopy, we show that YtfE exists in two conformational states, one of which has not been reported. Under high osmotic stress, YtfE adopts a homogeneous conformation (C state) similar to the known crystal structure. In a regular buffer, the N-terminal domain switches between the C state and a previously unidentified conformation (C' state), the latter of which has more space at the domain interface to allow the trafficking of NO molecules and thus is proposed to be a functionally active state. The conformational switch between the C and C' states is pivotal for facilitating NO access to the diiron core.
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Affiliation(s)
- Ruei-Fong Tsai
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Nien-Chen Lin
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Te-Yu Kao
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Yun-Hsuan Kuo
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Feng-Chun Lo
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Wen-Feng Liaw
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
| | - Yun-Wei Chiang
- Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan
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23
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Grechnikova M, Ženíšková K, Malych R, Mach J, Sutak R. Copper detoxification machinery of the brain-eating amoeba Naegleria fowleri involves copper-translocating ATPase and the antioxidant system. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2020; 14:126-135. [PMID: 33096396 PMCID: PMC7578549 DOI: 10.1016/j.ijpddr.2020.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 09/29/2020] [Accepted: 10/02/2020] [Indexed: 11/19/2022]
Abstract
Copper is a trace metal that is necessary for all organisms but toxic when present in excess. Different mechanisms to avoid copper toxicity have been reported to date in pathogenic organisms such as Cryptococcus neoformans and Candida albicans. However, little if anything is known about pathogenic protozoans despite their importance in human and veterinary medicine. Naegleria fowleri is a free-living amoeba that occurs naturally in warm fresh water and can cause a rapid and deadly brain infection called primary amoebic meningoencephalitis (PAM). Here, we describe the mechanisms employed by N. fowleri to tolerate high copper concentrations, which include various strategies such as copper efflux mediated by a copper-translocating ATPase and upregulation of the expression of antioxidant enzymes and obscure hemerythrin-like and protoglobin-like proteins. The combination of different mechanisms efficiently protects the cell and ensures its high copper tolerance, which can be advantageous both in the natural environment and in the host. Nevertheless, we demonstrate that copper ionophores are potent antiamoebic agents; thus, copper metabolism may be considered a therapeutic target. N. fowleri employs the combination of copper efflux and antioxidant system to ensure a high copper tolerance. Copper efflux in N. fowleri is mediated by a copper-translocating P-type ATPase. Copper ionophores have amoebicidal effect against N. fowleri and thus may be potentially used as antiamoebic agents. Iron-binding proteins hemerythrin and protoglobin are highly upregulated in N. fowleri under copper overload.
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Affiliation(s)
- Maria Grechnikova
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Kateřina Ženíšková
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Ronald Malych
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Jan Mach
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Robert Sutak
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic.
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24
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Ma Z, Caldas Nogueira ML, Marchi-Salvador DP, Davidson VL. Correlation of Conservation of Sequence and Structures of Mycobacterial Hemerythrin-like Proteins with Evolutionary Relationship and Host Pathogenicity. ACS OMEGA 2020; 5:23385-23392. [PMID: 32954191 PMCID: PMC7496005 DOI: 10.1021/acsomega.0c03338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 08/18/2020] [Indexed: 06/11/2023]
Abstract
The Rv2633c gene of Mycobacterium tuberculosis, which plays a role in infection, encodes a hemerythrin-like protein (HLP). The crystal structure of an orthologue of Rv2633c, the HLP from Mycobacterium kansasii, revealed that it possessed structural features that were distinct from other hemerythrins and HLPs. These and other orthologous proteins comprise a distinct class of non-heme di-iron HLPs that are only found in mycobacteria. This study presents an analysis and comparison of protein sequences, putative structures, and evolutionary relationship of HLPs from 20 mycobacterial species that are known to cause tuberculosis or pulmonary disorders in humans. The results of this analysis allowed correlation of the physicochemical characteristics of amino acid residues that are substituted in these highly conserved sequences with their position in structures, possible effects on function, and evolutionary relationships. The sequences of the proteins from M. tuberculosis, Mycobacterium bovis, and other members of the M. tuberculosis complex, which cause tuberculosis, have substitutions not seen in the other non-tuberculous mycobacteria. Furthermore, groups of species that are closely related, based on phylogenetic analysis, possess substitutions of otherwise conserved residues not seen in other species that are less related. This information is correlated with the occurrence and clinical presentations of these groups of mycobacterial species. The results of this study provide a framework for structure-function studies to determine how subtle differences in the primary sequences of members of this family of proteins correlate with their structures and activities and how this may influence the infectious properties of the host species.
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Affiliation(s)
- Zhongxin Ma
- Burnett
School of Biomedical Sciences, College of Medicine, University of Central Florida, 6900 Lake Nona Blvd., Orlando, Florida 32827, United
States
| | - Maria Luiza Caldas Nogueira
- Burnett
School of Biomedical Sciences, College of Medicine, University of Central Florida, 6900 Lake Nona Blvd., Orlando, Florida 32827, United
States
| | | | - Victor L. Davidson
- Burnett
School of Biomedical Sciences, College of Medicine, University of Central Florida, 6900 Lake Nona Blvd., Orlando, Florida 32827, United
States
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25
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Crystal structure of a hemerythrin-like protein from Mycobacterium kansasii and homology model of the orthologous Rv2633c protein of M. tuberculosis. Biochem J 2020; 477:567-581. [PMID: 31913442 PMCID: PMC6993866 DOI: 10.1042/bcj20190827] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 01/06/2020] [Accepted: 01/08/2020] [Indexed: 11/17/2022]
Abstract
Pathogenic and opportunistic mycobacteria have a distinct class of non-heme di-iron hemerythrin-like proteins (HLPs). The first to be isolated was the Rv2633c protein, which plays a role in infection by Mycobacterium tuberculosis (Mtb), but could not be crystallized. This work presents the first crystal structure of an ortholog of Rv2633c, the mycobacterial HLP from Mycobacterium kansasii (Mka). This structure differs from those of hemerythrins and other known HLPs. It consists of five α-helices, whereas all other HLP domains have four. In contrast with other HLPs, the HLP domain is not fused to an additional protein domain. The residues ligating and surrounding the di-iron site are also unique among HLPs. Notably, a tyrosine occupies the position normally held by one of the histidine ligands in hemerythrin. This structure was used to construct a homology model of Rv2633c. The structure of five α-helices is conserved and the di-iron site ligands are identical in Rv2633c. Two residues near the ends of helices in the Mka HLP structure are replaced with prolines in the Rv2633c model. This may account for structural perturbations that decrease the solubility of Rv2633c relative to Mka HLP. Clusters of residues that differ in charge or polarity between Rv2633c and Mka HLP that point outward from the helical core could reflect a specificity for potential differential interactions with other protein partners in vivo, which are related to function. The Mka HLP exhibited weaker catalase activity than Rv2633c. Evidence was obtained for the interaction of Mka HLP irons with nitric oxide.
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26
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Singh B, Das RS. Studies on the oxidative degradation of paracetamol by a μ-oxo-diiron(III) complex. CAN J CHEM 2020. [DOI: 10.1139/cjc-2019-0193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In higher organisms, metalloenzymes like cytochrome P450, containing a Fe(III) metal center, play an active role in metabolism of paracetamol (APAP). Here, we have chosen a mimicking μ-oxo-diiron complex, [Fe(III)2(μ-O)(phen)4(H2O)2]4+(1, phen = 1,10-phenanthroline), to study spectrophotometrically the kinetics of the redox interactions with APAP. In acidic buffer media (pH = 3.4–5.1), APAP quantitatively reduces 1 following first-order reaction kinetics. Each molecule of 1 accepts two electrons from APAP and is reduced to ferroin [Fe(phen)3]2+. On oxidation, APAP produces N-acetyl-p-benzoquinone imine (NAPQI), which on hydrolysis results in a mixture of benzoquinone, quinone oxime, acetamide, and acetic acid. In reaction media due to successive deprotonations, 1 exists in equilibrium with the species [Fe(III)2(μ-O)(phen)4(H2O)(OH)]3+(1a) and [Fe(III)2(μ-O)(phen)4(OH)2]2+(1b) (pKa= 3.71 and 5.28, respectively). The kinetic analyses suggest for an unusual reactivity order as 1 < 1a ≫ 1b. The mechanistic possibilities suggest that although 1 is reduced by concerted electron transfer (ET) – proton transfer (PT) mechanism, 1a and 1b may be reduced by a concerted PT–ET mechanism where a slow proton-abstraction step is followed by a rapid ET process. It seems that the initial activation of the bridging μ-oxo group by a proton-abstraction results in the higher reactivity of 1a.
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Affiliation(s)
- Bula Singh
- Department of Chemistry, Visva-Bharati, Santiniketan 731235, India
| | - Ranendu Sekhar Das
- Department of Chemistry, Ranaghat College, Nadia, West Bengal 741201, India
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27
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Nariya S, Kalyuzhnaya MG. Hemerythrins enhance aerobic respiration in Methylomicrobium alcaliphilum 20ZR, a methane-consuming bacterium. FEMS Microbiol Lett 2020; 367:5735436. [PMID: 32053143 DOI: 10.1093/femsle/fnaa003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 02/03/2020] [Indexed: 01/04/2023] Open
Abstract
Numerous hemerythrins, di-iron proteins, have been identified in prokaryote genomes, but in most cases their function remains elusive. Bacterial hemerythrin homologs (bacteriohemerythrins, Bhrs) may contribute to various cellular functions, including oxygen sensing, metal binding and antibiotic resistance. It has been proposed that methanotrophic Bhrs support methane oxidation by supplying oxygen to a core enzyme, particulate methane monooxygenase. In this study, the consequences of the overexpression or deletion of the Bhr gene (bhr) in Methylomicrobiam alcaliphillum 20ZR were investigated. We found that the bhrknockout (20ZRΔbhr) displays growth kinetics and methane consumption rates similar to wild type. However, the 20ZRΔbhr accumulates elevated concentrations of acetate at aerobic conditions, indicating slowed respiration. The methanotrophic strain overproducing Bhr shows increased oxygen consumption and reduced carbon-conversion efficiency, while its methane consumption rates remain unchanged. These results suggest that the methanotrophic Bhr proteins specifically contribute to oxygen-dependent respiration, while they have minimal, if any, input of oxygen for the methane oxidation machinery.
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Affiliation(s)
- Snehal Nariya
- Biology Department, 5500 Campanile Drive, San Diego, CA, USA
| | - Marina G Kalyuzhnaya
- Biology Department, 5500 Campanile Drive, San Diego, CA, USA.,Viral Information Institute, San Diego State University, 5500 Campanile Drive, San Diego, CA
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28
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Rahalkar MC, Bahulikar RA. Hemerythrins are widespread and conserved for methanotrophic guilds. GENE REPORTS 2018. [DOI: 10.1016/j.genrep.2018.04.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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