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Wang L, Guo Y, Shen Y, Yang K, Cai X, Zhang B, Liu Z, Zheng Y. Microbial production of sulfur-containing amino acids using metabolically engineered Escherichia coli. Biotechnol Adv 2024; 73:108353. [PMID: 38593935 DOI: 10.1016/j.biotechadv.2024.108353] [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: 12/21/2023] [Revised: 04/03/2024] [Accepted: 04/03/2024] [Indexed: 04/11/2024]
Abstract
L-Cysteine and L-methionine, as the only two sulfur-containing amino acids among the canonical 20 amino acids, possess distinct characteristics and find wide-ranging industrial applications. The use of different organisms for fermentative production of L-cysteine and L-methionine is gaining increasing attention, with Escherichia coli being extensively studied as the preferred strain. This preference is due to its ability to grow rapidly in cost-effective media, its robustness for industrial processes, the well-characterized metabolism, and the availability of molecular tools for genetic engineering. This review focuses on the genetic and molecular mechanisms involved in the production of these sulfur-containing amino acids in E. coli. Additionally, we systematically summarize the metabolic engineering strategies employed to enhance their production, including the identification of new targets, modulation of metabolic fluxes, modification of transport systems, dynamic regulation strategies, and optimization of fermentation conditions. The strategies and design principles discussed in this review hold the potential to facilitate the development of strain and process engineering for direct fermentation of sulfur-containing amino acids.
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Affiliation(s)
- Lijuan Wang
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China
| | - Yingying Guo
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China
| | - Yizhou Shen
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China
| | - Kun Yang
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China
| | - Xue Cai
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China
| | - Bo Zhang
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China
| | - Zhiqiang Liu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China.
| | - Yuguo Zheng
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China; Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, PR China
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Aoki H, Shinkai Y, Akiyama M, Yamazaki S, Nishida M, Kumagai Y. Extracellularly secreted cysteine derived from cystine regulates oxidative and electrophilic stress in HepG2 cells. Free Radic Res 2024:1-10. [PMID: 38733204 DOI: 10.1080/10715762.2024.2350524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/03/2024] [Indexed: 05/13/2024]
Abstract
While cysteine (CysSH) is known to be exported into the extracellular space, its biological significance is not well understood. The present study examined the movement of extracellular CysSH using stable isotope-labeled cystine (CysSSCys), which is transported into cells and reduced to CysSH. Exposure of HepG2 cells to 100 µM stable isotope-labeled CysSSCys resulted in 70 µM labeled CysSH in cell medium 1 h after CysSSCys exposure. When the cell medium was collected and incubated with either hydrogen peroxide (H2O2) or atmospheric electrophiles, such as 1,2-naphthoquinone, 1,4-naphthoquinone and 1,4-benzoquinone, CysSH in the cell medium was almost completely consumed. In contrast, extracellular levels of CysSH were unaltered during exposure of HepG2 cells to H2O2 for up to 2 h, suggesting redox cycling of CysSSCys/CysSH in the cell system. Experiments with and without changing cell medium containing CysSH from HepG2 cells revealed that oxidative and electrophilic modifications of cellular proteins, caused by exposure to H2O2 and 1,2-naphthoquinone, were significantly repressed by CysSH in the medium. We also examined participation of enzymes and/or antioxidants in intracellular reduction of CysSSCys to CysSH. These results provide new findings that extracellular CysSH derived from CysSSCys plays a role in the regulation of oxidative and electrophilic stress.
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Affiliation(s)
- Hanako Aoki
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan
| | - Yasuhiro Shinkai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan
- Environmental Biology Laboratory, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Tokyo, Japan
| | - Masahiro Akiyama
- Faculty of Pharmacy and Graduate School of Pharmaceutical Science, Keio University, Tokyo, Japan
| | - Satoshi Yamazaki
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan
| | - Motohiro Nishida
- Graduate School of Pharmaceutical Sciences, Kyusyu University, Fukuoka, Japan
| | - Yoshito Kumagai
- Environmental Biology Laboratory, Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan
- Graduate School of Pharmaceutical Sciences, Kyusyu University, Fukuoka, Japan
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Smirnova G, Tyulenev A, Sutormina L, Kalashnikova T, Muzyka N, Ushakov V, Samoilova Z, Oktyabrsky O. Regulation of Cysteine Homeostasis and Its Effect on Escherichia coli Sensitivity to Ciprofloxacin in LB Medium. Int J Mol Sci 2024; 25:4424. [PMID: 38674008 PMCID: PMC11050555 DOI: 10.3390/ijms25084424] [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: 03/28/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
Cysteine and its derivatives, including H2S, can influence bacterial virulence and sensitivity to antibiotics. In minimal sulfate media, H2S is generated under stress to prevent excess cysteine and, together with incorporation into glutathione and export into the medium, is a mechanism of cysteine homeostasis. Here, we studied the features of cysteine homeostasis in LB medium, where the main source of sulfur is cystine, whose import can create excess cysteine inside cells. We used mutants in the mechanisms of cysteine homeostasis and a set of microbiological and biochemical methods, including the real-time monitoring of sulfide and oxygen, the determination of cysteine and glutathione (GSH), and the expression of the Fur, OxyR, and SOS regulons genes. During normal growth, the parental strain generated H2S when switching respiration to another substrate. The mutations affected the onset time, the intensity and duration of H2S production, cysteine and glutathione levels, bacterial growth and respiration rates, and the induction of defense systems. Exposure to chloramphenicol and high doses of ciprofloxacin increased cysteine content and GSH synthesis. A high inverse relationship between log CFU/mL and bacterial growth rate before ciprofloxacin addition was revealed. The study points to the important role of maintaining cysteine homeostasis during normal growth and antibiotic exposure in LB medium.
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Affiliation(s)
- Galina Smirnova
- Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, Goleva 13, 614081 Perm, Russia; (A.T.); (L.S.); (T.K.); (N.M.); (V.U.); (Z.S.); (O.O.)
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Yang H, Zhang B, Wu Z, Pan J, Chen L, Xiu X, Cai X, Liu Z, Zheng Y. Synergistic application of atmospheric and room temperature plasma mutagenesis and adaptive laboratory evolution improves the tolerance of Escherichia coli to L-cysteine. Biotechnol J 2024; 19:e2300648. [PMID: 38403408 DOI: 10.1002/biot.202300648] [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: 11/20/2023] [Revised: 01/16/2024] [Accepted: 01/27/2024] [Indexed: 02/27/2024]
Abstract
L-Cysteine production through fermentation stands as a promising technology. However, excessive accumulation of L-cysteine poses a challenge due to the potential to inflict damage on cellular DNA. In this study, we employed a synergistic approach encompassing atmospheric and room temperature plasma mutagenesis (ARTP) and adaptive laboratory evolution (ALE) to improve L-cysteine tolerance in Escherichia coli. ARTP-treated populations obtained substantial enhancement in L-cysteine tolerance by ALE. Whole-genome sequencing, transcription analysis, and reverse engineering, revealed the pivotal role of an effective export mechanism mediated by gene eamB in augmenting L-cysteine resistance. The isolated tolerant strain, 60AP03/pTrc-cysEf , achieved a 2.2-fold increase in L-cysteine titer by overexpressing the critical gene cysEf during batch fermentation, underscoring its enormous potential for L-cysteine production. The production evaluations, supplemented with L-serine, further demonstrated the stability and superiority of tolerant strains in L-cysteine production. Overall, our work highlighted the substantial impact of the combined ARTP and ALE strategy in increasing the tolerance of E. coli to L-cysteine, providing valuable insights into improving L-cysteine overproduction, and further emphasized the potential of biotechnology in industrial production.
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Affiliation(s)
- Hui Yang
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
| | - Bo Zhang
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
| | - Zidan Wu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
| | - Jiayuan Pan
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
| | - Lifeng Chen
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
| | - Xiaoling Xiu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
| | - Xue Cai
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
| | - Zhiqiang Liu
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
| | - Yuguo Zheng
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, P. R. China
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Tikhomirova A, Rahman MM, Kidd SP, Ferrero RL, Roujeinikova A. Cysteine and resistance to oxidative stress: implications for virulence and antibiotic resistance. Trends Microbiol 2024; 32:93-104. [PMID: 37479622 DOI: 10.1016/j.tim.2023.06.010] [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: 05/18/2023] [Revised: 06/28/2023] [Accepted: 06/30/2023] [Indexed: 07/23/2023]
Abstract
Reactive oxygen species (ROS), including the superoxide radical anion (O2•-), hydrogen peroxide (H2O2), and the hydroxyl radical (•HO), are inherent components of bacterial metabolism in an aerobic environment. Bacteria also encounter exogenous ROS, such as those produced by the host cells during the respiratory burst. As ROS have the capacity to damage bacterial DNA, proteins, and lipids, detoxification of ROS is critical for bacterial survival. It has been recently recognised that low-molecular-weight (LMW) thiols play a central role in this process. Here, we review the emerging role of cysteine in bacterial resistance to ROS with a link to broader elements of bacterial lifestyle closely associated with cysteine-mediated oxidative stress response, including virulence and antibiotic resistance.
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Affiliation(s)
- Alexandra Tikhomirova
- Monash University, Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Melbourne, VIC 3800, Australia
| | - Mohammad M Rahman
- University of Kentucky, Department of Microbiology, Immunology and Molecular Genetics, Lexington, KY, USA
| | - Stephen P Kidd
- University of Adelaide, Department of Molecular and Biomedical Sciences, School of Biological Sciences, Adelaide, SA 5005, Australia; University of Adelaide, Research Centre for Infectious Disease (RCID) and Australian Centre for Antimicrobial Resistance Ecology (ACARE), Adelaide, SA 5005, Australia
| | - Richard L Ferrero
- Monash University, Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Melbourne, VIC 3800, Australia; Hudson Institute of Medical Research, Centre for Innate Immunity and Infectious Diseases, Melbourne, VIC 3168, Australia; Monash University, Department of Molecular and Translational Science, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Melbourne, VIC 3800, Australia
| | - Anna Roujeinikova
- Monash University, Department of Microbiology, Infection and Immunity Program, Monash Biomedicine Discovery Institute, Melbourne, VIC 3800, Australia; Monash University, Department of Biochemistry and Molecular Biology, Melbourne, VIC 3800, Australia.
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Srivastava A, De Corte D, Garcia JAL, Swan BK, Stepanauskas R, Herndl GJ, Sintes E. Interplay between autotrophic and heterotrophic prokaryotic metabolism in the bathypelagic realm revealed by metatranscriptomic analyses. MICROBIOME 2023; 11:239. [PMID: 37925458 PMCID: PMC10625248 DOI: 10.1186/s40168-023-01688-7] [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: 03/08/2023] [Accepted: 10/02/2023] [Indexed: 11/06/2023]
Abstract
BACKGROUND Heterotrophic microbes inhabiting the dark ocean largely depend on the settling of organic matter from the sunlit ocean. However, this sinking of organic materials is insufficient to cover their demand for energy and alternative sources such as chemoautotrophy have been proposed. Reduced sulfur compounds, such as thiosulfate, are a potential energy source for both auto- and heterotrophic marine prokaryotes. METHODS Seawater samples were collected from Labrador Sea Water (LSW, ~ 2000 m depth) in the North Atlantic and incubated in the dark at in situ temperature unamended, amended with 1 µM thiosulfate, or with 1 µM thiosulfate plus 10 µM glucose and 10 µM acetate (thiosulfate plus dissolved organic matter, DOM). Inorganic carbon fixation was measured in the different treatments and samples for metatranscriptomic analyses were collected after 1 h and 72 h of incubation. RESULTS Amendment of LSW with thiosulfate and thiosulfate plus DOM enhanced prokaryotic inorganic carbon fixation. The energy generated via chemoautotrophy and heterotrophy in the amended prokaryotic communities was used for the biosynthesis of glycogen and phospholipids as storage molecules. The addition of thiosulfate stimulated unclassified bacteria, sulfur-oxidizing Deltaproteobacteria (SAR324 cluster bacteria), Epsilonproteobacteria (Sulfurimonas sp.), and Gammaproteobacteria (SUP05 cluster bacteria), whereas, the amendment with thiosulfate plus DOM stimulated typically copiotrophic Gammaproteobacteria (closely related to Vibrio sp. and Pseudoalteromonas sp.). CONCLUSIONS The gene expression pattern of thiosulfate utilizing microbes specifically of genes involved in energy production via sulfur oxidation and coupled to CO2 fixation pathways coincided with the change in the transcriptional profile of the heterotrophic prokaryotic community (genes involved in promoting energy storage), suggesting a fine-tuned metabolic interplay between chemoautotrophic and heterotrophic microbes in the dark ocean. Video Abstract.
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Affiliation(s)
- Abhishek Srivastava
- Department of Functional and Evolutionary Ecology, Bio-Oceanography and Marine Biology Unit, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria.
- Konrad Lorenz Institute of Ethology, University of Veterinary Medicine Vienna, Savoyenstrasse 1a, 1160, Vienna, Austria.
| | - Daniele De Corte
- Institute for Chemistry and Biology of the Marine Environment, Carl Von Ossietzky University, Oldenburg, Germany
- Currently at Ocean Technology and Engineering Department, National Oceanography Centre, Southampton, UK
| | - Juan A L Garcia
- Department of Functional and Evolutionary Ecology, Bio-Oceanography and Marine Biology Unit, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
- Department of Informatics, INS La Ferreria, 08110, Montcada i Reixach, Spain
| | - Brandon K Swan
- National Biodefense Analysis and Countermeasures Center, Frederick, MD, 21702, USA
| | | | - Gerhard J Herndl
- Department of Functional and Evolutionary Ecology, Bio-Oceanography and Marine Biology Unit, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
- Department of Marine Microbiology and Biogeochemistry, NIOZ, Royal Netherlands Institute for Sea Research, AB Den Burg, The Netherlands
| | - Eva Sintes
- Ecosystem Oceanography Group (GRECO), Instituto Español de Oceanografía (IEO-CSIC), Centro Oceanográfico de Baleares, Palma, Spain.
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Smirnova GV, Tyulenev AV, Bezmaternykh KV, Muzyka NG, Ushakov VY, Oktyabrsky ON. Phosphate starvation is accompanied by disturbance of intracellular cysteine homeostasis in Escherichia coli. Res Microbiol 2023; 174:104108. [PMID: 37516155 DOI: 10.1016/j.resmic.2023.104108] [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: 06/05/2023] [Revised: 07/19/2023] [Accepted: 07/24/2023] [Indexed: 07/31/2023]
Abstract
Metabolic rearrangements that occur during depletion of essential nutrients can lead to accumulation of potentially dangerous metabolites. Here we showed that depletion of phosphate (Pi), accompanied by a sharp inhibition of growth and respiration, caused a transient excess of intracellular cysteine due to a decrease in the rate of protein synthesis. High cysteine level can be dangerous due to its ability to produce ROS and reduce Fe3+ to Fenton-reactive Fe2+. To prevent these negative effects, excess cysteine was mainly incorporated into glutathione (GSH), the intracellular level of which increased by 3 times, and was also exported to the medium and partially degraded to form H2S with participation of 3-mercaptopyruvate sulfotransferase (3MST). The addition of Pi to starving cells led to a sharp recovery of respiration and growth, GSH efflux into the medium and K+ influx into the cells. A pronounced coupling of Pi, GSH, and K+ fluxes was shown upon Pi depletion and addition, which may be necessary to maintain the ionic balance in the cytoplasm. We suggest that processes aimed at restoring cysteine homeostasis may be an integral part of the universal response to stress under different types of stress and for different types of bacteria.
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Affiliation(s)
- Galina V Smirnova
- Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, ul. Goleva 13, Perm, 614081, Russia.
| | - Aleksey V Tyulenev
- Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, ul. Goleva 13, Perm, 614081, Russia.
| | - Kseniya V Bezmaternykh
- Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, ul. Goleva 13, Perm, 614081, Russia.
| | - Nadezda G Muzyka
- Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, ul. Goleva 13, Perm, 614081, Russia.
| | - Vadim Y Ushakov
- Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, ul. Goleva 13, Perm, 614081, Russia.
| | - Oleg N Oktyabrsky
- Institute of Ecology and Genetics of Microorganisms, Perm Federal Research Center, Russian Academy of Sciences, ul. Goleva 13, Perm, 614081, Russia.
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Abstract
The metabolism of a bacterial cell stretches beyond its boundaries, often connecting with the metabolism of other cells to form extended metabolic networks that stretch across communities, and even the globe. Among the least intuitive metabolic connections are those involving cross-feeding of canonically intracellular metabolites. How and why are these intracellular metabolites externalized? Are bacteria simply leaky? Here I consider what it means for a bacterium to be leaky, and I review mechanisms of metabolite externalization from the context of cross-feeding. Despite common claims, diffusion of most intracellular metabolites across a membrane is unlikely. Instead, passive and active transporters are likely involved, possibly purging excess metabolites as part of homeostasis. Re-acquisition of metabolites by a producer limits the opportunities for cross-feeding. However, a competitive recipient can stimulate metabolite externalization and initiate a positive-feedback loop of reciprocal cross-feeding.
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Affiliation(s)
- James B McKinlay
- Department of Biology, Indiana University, Bloomington, Indiana, USA;
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Hirth N, Gerlach MS, Wiesemann N, Herzberg M, Große C, Nies DH. Full Copper Resistance in Cupriavidus metallidurans Requires the Interplay of Many Resistance Systems. Appl Environ Microbiol 2023:e0056723. [PMID: 37191542 DOI: 10.1128/aem.00567-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023] Open
Abstract
The metal-resistant bacterium Cupriavidus metallidurans uses its copper resistance components to survive the synergistic toxicity of copper ions and gold complexes in auriferous soils. The cup, cop, cus, and gig determinants encode as central component the Cu(I)-exporting PIB1-type ATPase CupA, the periplasmic Cu(I)-oxidase CopA, the transenvelope efflux system CusCBA, and the Gig system with unknown function, respectively. The interplay of these systems with each other and with glutathione (GSH) was analyzed. Copper resistance in single and multiple mutants up to the quintuple mutant was characterized in dose-response curves, Live/Dead-staining, and atomic copper and glutathione content of the cells. The regulation of the cus and gig determinants was studied using reporter gene fusions and in case of gig also RT-PCR studies, which verified the operon structure of gigPABT. All five systems contributed to copper resistance in the order of importance: Cup, Cop, Cus, GSH, and Gig. Only Cup was able to increase copper resistance of the Δcop Δcup Δcus Δgig ΔgshA quintuple mutant but the other systems were required to increase copper resistance of the Δcop Δcus Δgig ΔgshA quadruple mutant to the parent level. Removal of the Cop system resulted in a clear decrease of copper resistance in most strain backgrounds. Cus cooperated with and partially substituted Cop. Gig and GSH cooperated with Cop, Cus, and Cup. Copper resistance is thus the result of an interplay of many systems. IMPORTANCE The ability of bacteria to maintain homeostasis of the essential-but-toxic "Janus"-faced element copper is important for their survival in many natural environments but also in case of pathogenic bacteria in their respective host. The most important contributors to copper homeostasis have been identified in the last decades and comprise PIB1-type ATPases, periplasmic copper- and oxygen-dependent copper oxidases, transenvelope efflux systems, and glutathione; however, it is not known how all these players interact. This publication investigates this interplay and describes copper homeostasis as a trait emerging from a network of interacting resistance systems.
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Affiliation(s)
- Niklas Hirth
- Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | | | - Nicole Wiesemann
- Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Martin Herzberg
- Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Cornelia Große
- Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
| | - Dietrich H Nies
- Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany
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Zhao F, Xu H, Chen Y, Xiao J, Zhang M, Li Z, Liu J, Qi C. Actinobacillus pleuropneumoniae FliY and YdjN are involved in cysteine/cystine utilization, oxidative resistance, and biofilm formation but are not determinants of virulence. Front Microbiol 2023; 14:1169774. [PMID: 37250053 PMCID: PMC10213525 DOI: 10.3389/fmicb.2023.1169774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 04/10/2023] [Indexed: 05/31/2023] Open
Abstract
Introduction Actinobacillus pleuropneumoniae (A. pleuropneumoniae) is a member of Actinobacillus in family Pasteurellaceae. It is the causative agent of porcine pleuropneumonia, which has caused huge economic losses to pig industry over the world. Cysteine is a precursor of many important biomolecules and defense compounds in the cell. However, molecular mechanisms of cysteine transport in A. pleuropneumoniae are unclear. Methods In this study, gene-deleted mutants were generated and investigated, to reveal the roles of potential cysteine/cystine transport proteins FliY and YdjN of A. pleuropneumoniae. Results Our results indicated that the growth of A. pleuropneumoniae was not affected after fliY or ydjN single gene deletion, but absence of both FliY and YdjN decreased the growth ability significantly, when cultured in the chemically defined medium (CDM) supplemented with cysteine or cystine as the only sulfur source. A. pleuropneumoniae double deletion mutant ΔfliYΔydjN showed increased sensitivity to oxidative stress. Besides, trans-complementation of YdjN into ΔfliYΔydjN and wild type leads to increased biofilm formation in CDM. However, the virulence of ΔfliYΔydjN was not attenuated in mice or pigs. Discussion These findings suggest that A. pleuropneumoniae FliY and YdjN are involved in the cysteine/cystine acquisition, oxidative tolerance, and biofilm formation, but not contribute to the pathogenicity of A. pleuropneumoniae.
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Heieck K, Arnold ND, Brück TB. Metabolic stress constrains microbial L-cysteine production in Escherichia coli by accelerating transposition through mobile genetic elements. Microb Cell Fact 2023; 22:10. [PMID: 36642733 PMCID: PMC9841684 DOI: 10.1186/s12934-023-02021-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 01/09/2023] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND L-cysteine is an essential chemical building block in the pharmaceutical-, cosmetic-, food and agricultural sector. Conventionally, L-cysteine production relies on the conversion of keratinous biomass mediated by hydrochloric acid. Today, fermentative production based on recombinant E. coli, where L-cysteine production is streamlined and facilitated by synthetic plasmid constructs, is an alternative process at industrial scale. However, metabolic stress and the resulting production escape mechanisms in evolving populations are severely limiting factors during industrial biomanufacturing. We emulate high generation numbers typically reached in industrial fermentation processes with Escherichia coli harbouring L-cysteine production plasmid constructs. So far no genotypic and phenotypic alterations in early and late L-cysteine producing E. coli populations have been studied. RESULTS In a comparative experimental design, the E. coli K12 production strain W3110 and the reduced genome strain MDS42, almost free of insertion sequences, were used as hosts. Data indicates that W3110 populations acquire growth fitness at the expense of L-cysteine productivity within 60 generations, while production in MDS42 populations remains stable. For the first time, the negative impact of predominantly insertion sequence family 3 and 5 transposases on L-cysteine production is reported, by combining differential transcriptome analysis with NGS based deep plasmid sequencing. Furthermore, metabolic clustering of differentially expressed genes supports the hypothesis, that metabolic stress induces rapid propagation of plasmid rearrangements, leading to reduced L-cysteine yields in evolving populations over industrial fermentation time scales. CONCLUSION The results of this study implicate how selective deletion of insertion sequence families could be a new route for improving industrial L-cysteine or even general amino acid production using recombinant E. coli hosts. Instead of using minimal genome strains, a selective deletion of certain IS families could offer the benefits of adaptive laboratory evolution (ALE) while maintaining enhanced L-cysteine production stability.
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Affiliation(s)
- Kevin Heieck
- grid.6936.a0000000123222966Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
| | - Nathanael David Arnold
- grid.6936.a0000000123222966Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
| | - Thomas Bartholomäus Brück
- grid.6936.a0000000123222966Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
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12
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Li F, Wang J, Jiang Y, Guo Y, Liu N, Xiao S, Yao L, Li J, Zhuo C, He N, Liu B, Zhuo C. Adaptive Evolution Compensated for the Plasmid Fitness Costs Brought by Specific Genetic Conflicts. Pathogens 2023; 12:pathogens12010137. [PMID: 36678485 PMCID: PMC9861728 DOI: 10.3390/pathogens12010137] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/30/2022] [Accepted: 01/09/2023] [Indexed: 01/19/2023] Open
Abstract
New Delhi metallo-β-lactamase (NDM)-carrying IncX3 plasmids is important in the transmission of carbapenem resistance in Escherichia coli. Fitness costs related to plasmid carriage are expected to limit gene exchange; however, the causes of these fitness costs are poorly understood. Compensatory mutations are believed to ameliorate plasmid fitness costs and enable the plasmid's wide spread, suggesting that such costs are caused by specific plasmid-host genetic conflicts. By combining conjugation tests and experimental evolution with comparative genetic analysis, we showed here that the fitness costs related to ndm/IncX3 plasmids in E. coli C600 are caused by co-mutations of multiple host chromosomal genes related to sugar metabolism and cell membrane function. Adaptive evolution revealed that mutations in genes associated with oxidative stress, nucleotide and short-chain fatty acid metabolism, and cell membranes ameliorated the costs associated with plasmid carriage. Specific genetic conflicts associated with the ndm/IncX3 plasmid in E. coli C600 involve metabolism and cell-membrane-related genes, which could be ameliorated by compensatory mutations. Collectively, our findings could explain the wide spread of IncX3 plasmids in bacterial genomes, despite their potential cost.
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Affiliation(s)
- Feifeng Li
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
| | - Jiong Wang
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
| | - Ying Jiang
- Department of Respiratory Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
| | - Yingyi Guo
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
| | - Ningjing Liu
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
| | - Shunian Xiao
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
| | - Likang Yao
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
| | - Jiahui Li
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
| | - Chuyue Zhuo
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
| | - Nanhao He
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
| | - Baomo Liu
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Sun Yat-sen Univesity, Guangzhou 510030, China
- Correspondence: (B.L.); (C.Z.)
| | - Chao Zhuo
- State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510030, China
- Correspondence: (B.L.); (C.Z.)
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13
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The Inactivation of LPS Biosynthesis Genes in E. coli Cells Leads to Oxidative Stress. Cells 2022; 11:cells11172667. [PMID: 36078074 PMCID: PMC9454879 DOI: 10.3390/cells11172667] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/22/2022] [Accepted: 08/25/2022] [Indexed: 11/17/2022] Open
Abstract
Impaired lipopolysaccharide biosynthesis in Gram-negative bacteria results in the “deep rough” phenotype, which is characterized by increased sensitivity of cells to various hydrophobic compounds, including antibiotics novobiocin, actinomycin D, erythromycin, etc. The present study showed that E. coli mutants carrying deletions of the ADP-heptose biosynthesis genes became hypersensitive to a wide range of antibacterial drugs: DNA gyrase inhibitors, protein biosynthesis inhibitors (aminoglycosides, tetracycline), RNA polymerase inhibitors (rifampicin), and β-lactams (carbenicillin). In addition, it was found that inactivation of the gmhA, hldE, rfaD, and waaC genes led to dramatic changes in the redox status of cells: a decrease in the pool of reducing NADPH and ATP equivalents, the concentration of intracellular cysteine, a change in thiol homeostasis, and a deficiency in the formation of hydrogen sulfide. In “deep rough” mutants, intensive formation of reactive oxygen species was observed, which, along with a lack of reducing agents, such as reactive sulfur species or NADPH, leads to oxidative stress and an increase in the number of dead cells in the population. Within the framework of modern ideas about the role of oxidative stress as a universal mechanism of the bactericidal action of antibiotics, inhibition of the enzymes of ADP-heptose biosynthesis is a promising direction for increasing the effectiveness of existing antibiotics and solving the problem of multidrug resistance.
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14
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Characterization of glutamate‐cysteine ligase and glutathione synthetase from the δ‐proteobacterium
Myxococcus xanthus. Proteins 2022; 90:1547-1560. [DOI: 10.1002/prot.26333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/01/2022] [Accepted: 03/07/2022] [Indexed: 11/09/2022]
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15
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Usuda Y, Nishio Y, Nonaka G, Hara Y. Microbial Production Potential of Pantoea ananatis: From Amino Acids to Secondary Metabolites. Microorganisms 2022; 10:microorganisms10061133. [PMID: 35744651 PMCID: PMC9231021 DOI: 10.3390/microorganisms10061133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/25/2022] [Accepted: 05/27/2022] [Indexed: 11/16/2022] Open
Abstract
Pantoea ananatis, a gram-negative bacterium belonging to the Erwiniaceae family, is a well-known phytopathogen isolated from many ecological niches and plant hosts. However, this bacterium also provides us with various beneficial characteristics, such as the growth promotion of their host plants and increased crop yield. Some isolated non-pathogenic strains are promising for the microbial production of useful substances. P. ananatis AJ13355 was isolated as an acidophilic bacterium and was used as an excellent host to produce L-glutamic acid under acidic conditions. The genome sequence of P. ananatis AJ13355 was determined, and specific genome-engineering technologies were developed. As a result, P. ananatis was successfully used to construct a bacterial strain that produces cysteine, a sulfur-containing amino acid that has been difficult to produce through fermentation because of complex regulation. Furthermore, by heterologous expression including plant-derived genes, construction of a strain that produces isoprenoids such as isoprene and linalool as secondary metabolites was achieved. P. ananatis is shown to be a useful host for the production of secondary metabolites, as well as amino acids, and is expected to be used as a platform for microbial production of bioactive substances, aromatic substances, and other high-value-added substances of plant origin in the future.
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Affiliation(s)
- Yoshihiro Usuda
- Research and Business Planning Department, Ajinomoto Co., Inc., Tokyo 104-8315, Japan
- Correspondence: ; Tel.: +81-70-4361-3762; Fax: +81-3-5250-8352
| | - Yousuke Nishio
- Research Institute for Bioscience Products & Fine Chemicals, Ajinomoto Co., Inc., Kawasaki 210-8681, Japan; (Y.N.); (Y.H.)
| | - Gen Nonaka
- Ajinomoto-Genetika Research Institute, Moscow 117545, Russia;
| | - Yoshihiko Hara
- Research Institute for Bioscience Products & Fine Chemicals, Ajinomoto Co., Inc., Kawasaki 210-8681, Japan; (Y.N.); (Y.H.)
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16
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Salaskar DA, Padwal MK, Gupta A, Basu B, Kale SP. Proteomic Perspective of Cadmium Tolerance in Providencia rettgeri Strain KDM3 and Its In-situ Bioremediation Potential in Rice Ecosystem. Front Microbiol 2022; 13:852697. [PMID: 35558133 PMCID: PMC9086847 DOI: 10.3389/fmicb.2022.852697] [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: 01/11/2022] [Accepted: 03/16/2022] [Indexed: 11/13/2022] Open
Abstract
In this study, a multi-metal-tolerant natural bacterial isolate Providencia rettgeri strain KDM3 from an industrial effluent in Mumbai, India, showed high cadmium (Cd) tolerance. Providencia rettgeri grew in the presence of more than 100 ppm (880 μM) Cd (LD50 = 100 ppm) and accumulated Cd intracellularly. Following Cd exposure, a comparative proteome analysis revealed molecular mechanisms underlying Cd tolerance. Among a total of 69 differentially expressed proteins (DEPs) in Cd-exposed cells, de novo induction of ahpCF operon proteins and L-cysteine/L-cystine shuttle protein FliY was observed, while Dps and superoxide dismutase proteins were overexpressed, indicating upregulation of a robust oxidative stress defense. ENTRA1, a membrane transporter showing homology to heavy metal transporter, was also induced de novo. In addition, the protein disaggregation chaperone ClpB, trigger factor, and protease HslU were also overexpressed. Notably, 46 proteins from the major functional category of energy metabolism were found to be downregulated. Furthermore, the addition of P. rettgeri to Cd-spiked soil resulted in a significant reduction in the Cd content [roots (11%), shoot (50%), and grains (46%)] of the rice plants. Cd bioaccumulation of P. rettgeri improved plant growth and grain yield. We conclude that P. rettgeri, a highly Cd-tolerant bacterium, is an ideal candidate for in-situ bioremediation of Cd-contaminated agricultural soils.
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Affiliation(s)
- Darshana A Salaskar
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Mahesh K Padwal
- Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Alka Gupta
- Applied Genomics Section, Bhabha Atomic Research Centre, Mumbai, India
| | - Bhakti Basu
- Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Sharad P Kale
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, India
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17
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Roth M, Jaquet V, Lemeille S, Bonetti EJ, Cambet Y, François P, Krause KH. Transcriptomic Analysis of E. coli after Exposure to a Sublethal Concentration of Hydrogen Peroxide Revealed a Coordinated Up-Regulation of the Cysteine Biosynthesis Pathway. Antioxidants (Basel) 2022; 11:antiox11040655. [PMID: 35453340 PMCID: PMC9026346 DOI: 10.3390/antiox11040655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/24/2022] [Accepted: 03/25/2022] [Indexed: 12/13/2022] Open
Abstract
Hydrogen peroxide (H2O2) is a key defense component of host-microbe interaction. However, H2O2 concentrations generated by immune cells or epithelia are usually insufficient for bacterial killing and rather modulate bacterial responses. Here, we investigated the impact of sublethal H2O2 concentration on gene expression of E. coli BW25113 after 10 and 60 min of exposure. RNA-seq analysis revealed that approximately 12% of bacterial genes were strongly dysregulated 10 min following exposure to 2.5 mM H2O2. H2O2 exposure led to the activation of a specific antioxidant response and a general stress response. The latter was characterized by a transient down-regulation of genes involved in general metabolism, such as nucleic acid biosynthesis and translation, with a striking and coordinated down-regulation of genes involved in ribosome formation, and a sustained up-regulation of the SOS response. We confirmed the rapid transient and specific response mediated by the transcription factor OxyR leading to up-regulation of antioxidant systems, including the catalase-encoding gene (katG), that rapidly degrade extracellular H2O2 and promote bacterial survival. We documented a strong and transient up-regulation of genes involved in sulfur metabolism and cysteine biosynthesis, which are under the control of the transcription factor CysB. This strong specific transcriptional response to H2O2 exposure had no apparent impact on bacterial survival, but possibly replenishes the stores of oxidized cysteine and glutathione. In summary, our results demonstrate that different stress response mechanisms are activated by H2O2 exposure and highlight the cysteine synthesis as an antioxidant response in E. coli.
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Affiliation(s)
- Myriam Roth
- Department of Pathology and Immunology, Medical School, University of Geneva, 1211 Geneva, Switzerland; (V.J.); (S.L.); (K.-H.K.)
- Correspondence: ; Tel.: +41-223-794-257
| | - Vincent Jaquet
- Department of Pathology and Immunology, Medical School, University of Geneva, 1211 Geneva, Switzerland; (V.J.); (S.L.); (K.-H.K.)
- REaders, Assay Development & Screening Unit (READS Unit), Faculty of Medecine, University of Geneva, 1211 Geneva, Switzerland;
| | - Sylvain Lemeille
- Department of Pathology and Immunology, Medical School, University of Geneva, 1211 Geneva, Switzerland; (V.J.); (S.L.); (K.-H.K.)
| | - Eve-Julie Bonetti
- Genomic Research Laboratory, Infectious Diseases Service, University Hospitals Geneva Medical Center, Michel-Servet 1, 1211 Geneva, Switzerland; (E.-J.B.); (P.F.)
| | - Yves Cambet
- REaders, Assay Development & Screening Unit (READS Unit), Faculty of Medecine, University of Geneva, 1211 Geneva, Switzerland;
| | - Patrice François
- Genomic Research Laboratory, Infectious Diseases Service, University Hospitals Geneva Medical Center, Michel-Servet 1, 1211 Geneva, Switzerland; (E.-J.B.); (P.F.)
| | - Karl-Heinz Krause
- Department of Pathology and Immunology, Medical School, University of Geneva, 1211 Geneva, Switzerland; (V.J.); (S.L.); (K.-H.K.)
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18
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Guo K, Feng X, Sun W, Han S, Wu S, Gao H. NapB Restores cytochrome c biosynthesis in bacterial dsbD-deficient mutants. Commun Biol 2022; 5:87. [PMID: 35064202 PMCID: PMC8782879 DOI: 10.1038/s42003-022-03034-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 01/05/2022] [Indexed: 11/10/2022] Open
Abstract
Cytochromes c (cyts c), essential for respiration and photosynthesis in eukaryotes, confer bacteria respiratory versatility for survival and growth in natural environments. In bacteria having a cyt c maturation (CCM) system, DsbD is required to mediate electron transport from the cytoplasm to CcmG of the Ccm apparatus. Here with cyt c-rich Shewanella oneidensis as the research model, we identify NapB, a cyt c per se, that suppresses the CCM defect of a dsbD mutant during anaerobiosis, when NapB is produced at elevated levels, a result of activation by cAMP-Crp. Data are then presented to suggest that NapB reduces CcmG, leading to the suppression. We further show that NapB proteins capable of rescuing CCM in the dsbD mutant form a small distinct clade. The study sheds light on multifunctionality of cyts c, and more importantly, unravels a self-salvation strategy through which bacteria have evolved to better adjust to the natural world. The DsbD protein is normally required for cytochrome c maturation (Ccm) in bacteria. With cytochrome c-rich Shewanella oneidensis as the research model, NapB, the small subunit of the nitrate reductase which is a cytochrome c per se, was found to suppress the Ccm defect resulting from DsbD loss under anaerobic conditions.
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19
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Shahbazi M, Tohidfar M, Azimzadeh Irani M, Moheb Seraj RG. Functional annotation and evaluation of hypothetical proteins in cyanobacterium Synechocystis sp. PCC 6803. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2022. [DOI: 10.1016/j.bcab.2021.102246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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20
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Genetic Determinants of Stress Resistance in Desiccated Salmonella enterica. Appl Environ Microbiol 2021; 87:e0168321. [PMID: 34586905 DOI: 10.1128/aem.01683-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteric pathogens, including Salmonella, are capable of long-term survival after desiccation and resist heat treatments that are lethal to hydrated cells. The mechanisms of dry-heat resistance differ from those of wet-heat resistance. To elucidate the mechanisms of dry-heat resistance in Salmonella, screening of the dry-heat resistance of 108 Salmonella strains, representing 39 serotypes, identified the 22 most resistant and the 8 most sensitive strains for comparative genome analysis. A total of 289 genes of the accessory genome were differently distributed between resistant and sensitive strains. Among these genes, 28 proteins with a putative relationship to stress resistance were selected for to quantify relative gene expression before and after desiccation and expression by solid-state cultures on agar plates relative to cultures growing in liquid culture media. Of these 28 genes, 15 genes were upregulated (P < 0.05) after desiccation or by solid-state cultures on agar plates. These 15 genes were cloned into the low-copy-number vector pRK767 under the control of the lacZ promoter. The expression of 6 of these 15 genes increased (P < 0.05) resistance to dry heat and to treatment with pressure of 500 MPa. Our finding extends the knowledge of mechanisms of stress resistance in desiccated Salmonella to improve control of this bacterium in dry food. IMPORTANCE This study directly targeted an increasing threat to food safety and developed knowledge and targeted strategies that can be used by the food industry to help reduce the risk of foodborne illness in their dry products and thereby reduce the overall burden of foodborne illness. Genomic and physiological analyses have elucidated mechanisms of bacterial resistance to many food preservation technologies, including heat, pressure, disinfection chemicals, and UV light; however, information on bacterial mechanisms of resistance to dry heat is scarce. Mechanisms of tolerance to desiccation likely also contribute to resistance to dry heat, but this assumption has not been verified experimentally. It remains unclear how mechanisms of resistance to wet heat relate to dry-heat resistance. Thus, this study will fill a knowledge gap to improve the safety of dry foods.
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21
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Impact of spaceflight and artificial gravity on sulfur metabolism in mouse liver: sulfur metabolomic and transcriptomic analysis. Sci Rep 2021; 11:21786. [PMID: 34750416 PMCID: PMC8575787 DOI: 10.1038/s41598-021-01129-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 10/11/2021] [Indexed: 12/30/2022] Open
Abstract
Spaceflight induces hepatic damage, partially owing to oxidative stress caused by the space environment such as microgravity and space radiation. We examined the roles of anti-oxidative sulfur-containing compounds on hepatic damage after spaceflight. We analyzed the livers of mice on board the International Space Station for 30 days. During spaceflight, half of the mice were exposed to artificial earth gravity (1 g) using centrifugation cages. Sulfur-metabolomics of the livers of mice after spaceflight revealed a decrease in sulfur antioxidants (ergothioneine, glutathione, cysteine, taurine, thiamine, etc.) and their intermediates (cysteine sulfonic acid, hercynine, N-acethylserine, serine, etc.) compared to the controls on the ground. Furthermore, RNA-sequencing showed upregulation of gene sets related to oxidative stress and sulfur metabolism, and downregulation of gene sets related to glutathione reducibility in the livers of mice after spaceflight, compared to controls on the ground. These changes were partially mitigated by exposure to 1 g centrifugation. For the first time, we observed a decrease in sulfur antioxidants based on a comprehensive analysis of the livers of mice after spaceflight. Our data suggest that a decrease in sulfur-containing compounds owing to both microgravity and other spaceflight environments (radiation and stressors) contributes to liver damage after spaceflight.
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22
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Italiano CJ, Pu L, Violi JP, Duggin IG, Rodgers KJ. Cysteine biosynthesis contributes to β-methylamino-l-alanine tolerance in Escherichia coli. Res Microbiol 2021; 172:103852. [PMID: 34246779 DOI: 10.1016/j.resmic.2021.103852] [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: 03/14/2021] [Revised: 06/26/2021] [Accepted: 06/29/2021] [Indexed: 11/25/2022]
Abstract
In contrast to mammalian cells, bacteria such as Escherichia coli have been shown to display tolerance towards the neurotoxin β-methylamino-l-alanine (BMAA) suggesting that these prokaryotes possess a way to metabolise BMAA or its products, resulting in their export, degradation, or detoxification. Single gene deletion mutants of E. coli K-12 with inactivated amino acid biosynthesis pathways were treated with 500 μg/ml BMAA and the resulting growth was monitored. Wild type E. coli and most of the gene deletion mutants displayed unaltered growth in the presence of BMAA over 12 h. Conversely, deletion of genes in the cysteine biosynthesis pathway, cysE, cysK or cysM resulted in a BMAA dose-dependent growth delay in minimal medium. Through further studies of the ΔcysE strain, we observed increased susceptibility to oxidative stress from H2O2 in minimal medium, and disruptions in glutathione levels and oxidation state. The cysteine biosynthesis pathway is therefore linked to the tolerance of BMAA and oxidative stress in E. coli, which potentially represents a mechanism of BMAA detoxification.
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Affiliation(s)
- Carly J Italiano
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - Lisa Pu
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - Jake P Violi
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - Iain G Duggin
- The iThree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - Kenneth J Rodgers
- School of Life Sciences, University of Technology Sydney, Ultimo, NSW 2007, Australia.
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23
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Goff JL, Schaefer JK, Yee N. Extracellular sulfite is protective against reactive oxygen species and antibiotic stress in Shewanella oneidensis MR-1. ENVIRONMENTAL MICROBIOLOGY REPORTS 2021; 13:394-400. [PMID: 33870629 DOI: 10.1111/1758-2229.12947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/04/2021] [Indexed: 06/12/2023]
Abstract
In this study, we investigated the extracellular reactive sulfur species produced by Shewanella oneidensis MR-1 during growth. The results showed that sulfite is the major extracellular sulfur metabolite released to the growth medium under both aerobic and anaerobic growth conditions. Exogenous sulfite at physiological concentrations protected S. oneidensis MR-1 from hydrogen peroxide toxicity and enhanced tolerance to the beta-lactam antibiotics cefazolin, meropenem, doripenem and ertapenem. These findings suggest that the release of extracellular sulfite is a bacterial defence mechanism that plays a role in the mitigation of environmental stress.
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Affiliation(s)
- Jennifer L Goff
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA
| | - Jeffra K Schaefer
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, USA
| | - Nathan Yee
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, USA
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24
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Wan F, Feng X, Yin J, Gao H. Distinct H 2O 2-Scavenging System in Yersinia pseudotuberculosis: KatG and AhpC Act Together to Scavenge Endogenous Hydrogen Peroxide. Front Microbiol 2021; 12:626874. [PMID: 34025596 PMCID: PMC8139631 DOI: 10.3389/fmicb.2021.626874] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 03/22/2021] [Indexed: 01/09/2023] Open
Abstract
To colonize in the digestive tract of animals and humans, Yersinia pseudotuberculosis has to deal with reactive oxygen species (ROS) produced by host cells and microbiota. However, an understanding of the ROS-scavenging systems and their regulation in this bacterium remains largely elusive. In this study, we identified OxyR as the master transcriptional regulator mediating cellular responses to hydrogen peroxide (H2O2) in Y. pseudotuberculosis through genomics and transcriptomics analyses. OxyR activates transcription of diverse genes, especially the core members of its regulon, including those encoding catalases, peroxidases, and thiol reductases. The data also suggest that sulfur species and manganese may play a particular role in the oxidative stress response of Y. pseudotuberculosis. Among the three H2O2-scavenging systems in Y. pseudotuberculosis, catalase/peroxidase KatE functions as the primary scavenger for high levels of H2O2; NADH peroxidase alkyl hydroperoxide reductase (AhpR) and catalase KatG together are responsible for removing low levels of H2O2. The simultaneous loss of both AhpC (the peroxidatic component of AhpR) and KatG results in activation of OxyR. Moreover, we found that AhpC, unlike its well-characterized Escherichia coli counterpart, has little effect on protecting cells against toxicity of organic peroxides. These findings provide not only novel insights into the structural and functional diversity of bacterial H2O2-scavenging systems but also a basic understanding of how Y. pseudotuberculosis copes with oxidative stress.
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Affiliation(s)
- Fen Wan
- College of Laboratory Medicine, Hangzhou Medical College, Hangzhou, China
| | - Xue Feng
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Jianhua Yin
- College of Biotechnology and Bioengineering, Zhenjiang University of Technology, Hangzhou, China
| | - Haichun Gao
- Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, China
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25
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Jin H, Dhanasingh I, Sung J, La JW, Lee Y, Lee EM, Kang Y, Lee DY, Lee SH, Lee D. The sulfur formation system mediating extracellular cysteine-cystine recycling in Fervidobacterium islandicum AW-1 is associated with keratin degradation. Microb Biotechnol 2021; 14:938-952. [PMID: 33320434 PMCID: PMC8085985 DOI: 10.1111/1751-7915.13717] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 11/08/2020] [Accepted: 11/11/2020] [Indexed: 11/27/2022] Open
Abstract
Most extremophilic anaerobes possess a sulfur formation (Suf) system for Fe-S cluster biogenesis. In addition to its essential role in redox chemistry and stress responses of Fe-S cluster proteins, the Suf system may play an important role in keratin degradation by Fervidobacterium islandicum AW-1. Comparative genomics of the order Thermotogales revealed that the feather-degrading F. islandicum AW-1 has a complete Suf-like machinery (SufCBDSU) that is highly expressed in cells grown on native feathers in the absence of elemental sulfur (S0 ). On the other hand, F. islandicum AW-1 exhibited a significant retardation in the Suf system-mediated keratin degradation in the presence of S0 . Detailed differential expression analysis of sulfur assimilation machineries unveiled the mechanism by which an efficient sulfur delivery from persulfurated SufS to SufU is achieved during keratinolysis under sulfur starvation. Indeed, addition of SufS-SufU to cell extracts containing keratinolytic proteases accelerated keratin decomposition in vitro under reducing conditions. Remarkably, mass spectrometric analysis of extracellular and intracellular levels of amino acids suggested that redox homeostasis within cells coupled to extracellular cysteine and cystine recycling might be a prerequisite for keratinolysis. Taken together, these results suggest that the Suf-like machinery including the SufS-SufU complex may contribute to sulfur availability for an extracellular reducing environment as well as intracellular redox homeostasis through cysteine released from keratin hydrolysate under starvation conditions.
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Affiliation(s)
- Hyeon‐Su Jin
- Department of BiotechnologyYonsei UniversitySeoul03722South Korea
| | - Immanuel Dhanasingh
- Department of Cellular and Molecular MedicineChosun University School of MedicineGwangju61452South Korea
| | - Jae‐Yoon Sung
- Department of BiotechnologyYonsei UniversitySeoul03722South Korea
| | - Jae Won La
- Department of BiotechnologyYonsei UniversitySeoul03722South Korea
| | - Yena Lee
- Department of BiotechnologyYonsei UniversitySeoul03722South Korea
| | - Eun Mi Lee
- Department of Agricultural BiotechnologyCenter for Food and BioconvergenceResearch Institute for Agricultural and Life SciencesSeoul National UniversitySeoul08826South Korea
| | - Yujin Kang
- Department of Bio and Fermentation Convergence TechnologyBK21 PLUS ProgramKookmin UniversitySeoul02707Korea
| | - Do Yup Lee
- Department of Agricultural BiotechnologyCenter for Food and BioconvergenceResearch Institute for Agricultural and Life SciencesSeoul National UniversitySeoul08826South Korea
| | - Sung Haeng Lee
- Department of Cellular and Molecular MedicineChosun University School of MedicineGwangju61452South Korea
| | - Dong‐Woo Lee
- Department of BiotechnologyYonsei UniversitySeoul03722South Korea
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26
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Ono K, Kitamura Y, Zhang T, Tsutsuki H, Rahman A, Ihara T, Akaike T, Sawa T. Cysteine Hydropersulfide Inactivates β-Lactam Antibiotics with Formation of Ring-Opened Carbothioic S-Acids in Bacteria. ACS Chem Biol 2021; 16:731-739. [PMID: 33781062 DOI: 10.1021/acschembio.1c00027] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Hydrogen sulfide (H2S) formed during sulfur metabolism in bacteria has been implicated in the development of intrinsic resistance to antibacterial agents. Despite the conversion of H2S to hydropersulfides greatly enhancing the biochemical properties of H2S such as antioxidant activity, the effects of hydropersulfides on antibiotic resistance have remained unknown. In this work, we investigated the effects of H2S alone or together with cystine to form cysteine hydropersulfide (CysSSH) on the activities of antibacterial agents. By using the disc diffusion test, we found that CysSSH treatment effectively inactivated β-lactams of the penicillin class (penicillin G and ampicillin) and the carbapenem class (meropenem). These β-lactams were resistant to treatment with H2S alone or cystine alone. In contrast, cephalosporin class β-lactams (cefaclor and cefoperazone) and non-β-lactam antibiotics (tetracycline, kanamycin, erythromycin, and ofloxacin) were stable after CysSSH treatment. Chromatographic and mass spectrometric analyses revealed that CysSSH directly reacted with β-lactams to form β-lactam ring-opened carbothioic S-acids (BL-COSH). Furthermore, we demonstrated that certain bacteria (e.g., Escherichia coli and Staphylococcus aureus) efficiently decomposed β-lactam antibiotics to form BL-COSH, which were transported to the extracellular space. These data suggest that CysSSH-mediated β-lactam decomposition may contribute to intrinsic bacterial resistance to β-lactams. BL-COSH may become useful biomarkers for CysSSH-mediated β-lactam resistance and for investigation of potential antibacterial adjuvants that can enhance the antibacterial activity of β-lactams by reducing the hydropersulfides in bacteria.
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Affiliation(s)
- Katsuhiko Ono
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku Kumamoto 860-8556, Japan
| | - Yusuke Kitamura
- Division of Materials Science and Chemistry, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku Kumamoto 860-8555, Japan
| | - Tianli Zhang
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku Kumamoto 860-8556, Japan
| | - Hiroyasu Tsutsuki
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku Kumamoto 860-8556, Japan
| | - Azizur Rahman
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku Kumamoto 860-8556, Japan
| | - Toshihiro Ihara
- Division of Materials Science and Chemistry, Faculty of Advanced Science and Technology, Kumamoto University, 2-39-1 Kurokami, Chuo-ku Kumamoto 860-8555, Japan
| | - Takaaki Akaike
- Department of Environmental Medicine and Molecular Toxicology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Tomohiro Sawa
- Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku Kumamoto 860-8556, Japan
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27
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Manceau A, Nagy KL, Glatzel P, Bourdineaud JP. Acute Toxicity of Divalent Mercury to Bacteria Explained by the Formation of Dicysteinate and Tetracysteinate Complexes Bound to Proteins in Escherichia coli and Bacillus subtilis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:3612-3623. [PMID: 33629845 DOI: 10.1021/acs.est.0c05202] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Bacteria are the most abundant organisms on Earth and also the major life form affected by mercury (Hg) poisoning in aquatic and terrestrial food webs. In this study, we applied high energy-resolution X-ray absorption near edge structure (HR-XANES) spectroscopy to bacteria with intracellular concentrations of Hg as low as 0.7 ng/mg (ppm) for identifying the intracellular molecular forms and trafficking pathways of Hg in bacteria at environmentally relevant concentrations. Gram-positive Bacillus subtilis and Gram-negative Escherichia coli were exposed to three Hg species: HgCl2, Hg-dicysteinate (Hg(Cys)2), and Hg-dithioglycolate (Hg(TGA)2). In all cases, Hg was transformed into new two- and four-coordinate cysteinate complexes, interpreted to be bound, respectively, to the consensus metal-binding CXXC motif and zinc finger domains of proteins, with glutathione acting as a transfer ligand. Replacement of zinc cofactors essential to gene regulatory proteins with Hg would inhibit vital functions such as DNA transcription and repair and is suggested to be a main cause of Hg genotoxicity.
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Affiliation(s)
- Alain Manceau
- Université Grenoble Alpes, CNRS, ISTerre, CS 40700, 38058 Grenoble, France
| | - Kathryn L Nagy
- Department of Earth and Environmental Sciences, University of Illinois at Chicago, MC-186, 845 West Taylor Street, Chicago, Illinois 60607, United States
| | - Pieter Glatzel
- European Synchrotron Radiation Facility (ESRF), 71 Rue des Martyrs, 38000 Grenoble, France
| | - Jean-Paul Bourdineaud
- Institut Européen de Chimie et Biologie, Université de Bordeaux, CNRS, UMR 5234, 2 rue Escarpit, 33607 Pessac, France
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28
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Morigasaki S, Umeyama A, Kawano Y, Aizawa Y, Ohtsu I. Defect of RNA pyrophosphohydrolase RppH enhances fermentative production of L-cysteine in Escherichia coli. J GEN APPL MICROBIOL 2021; 66:307-314. [PMID: 32779574 DOI: 10.2323/jgam.2019.12.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Fermentative production of L-cysteine has been established using Escherichia coli. In that procedure, thiosulfate is a beneficial sulfur source, whereas repressing sulfate utilization. We first found that thiosulfate decreased transcript levels of genes related to sulfur assimilation, particularly whose expression is controlled by the transcription factor CysB. Therefore, a novel approach, i.e. increment of expression of genes involved in sulfur-assimilation, was attempted for further improvement of L-cysteine overproduction. Disruption of the rppH gene significantly augmented transcript levels of the cysD, cysJ, cysM and yeeE genes (≥1.5-times) in medium containing sulfate as a sole sulfur source, probably because the rppH gene encodes mRNA pyrophosphohydrolase that triggers degradation of certain mRNAs. In addition, the ΔrppH strain appeared to preferentially uptake thiosulfate rather than sulfate, though thiosulfate dramatically reduced expression of the known sulfate/thiosulfate transporter complexes in both ΔrppH and wild-type cells. We also found that both YeeE and YeeD are required for the strain without the transporters to grow in the presence of thiosulfate as a sole sulfur source. Therefore, yeeE and yeeD are assigned as genes responsible for thiosulfate uptake (tsuA and tsuB, respectively). In final, we applied the ΔrppH strain to the fermentative production of L-cysteine. Disruption of the rppH gene enhanced L-cysteine biosynthesis, as a result, a strain producing approximately twice as much L-cysteine as the control strain was obtained.
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Affiliation(s)
- Susumu Morigasaki
- Graduate School of Life and Environmental Sciences, University of Tsukuba
| | | | - Yusuke Kawano
- Graduate School of Life and Environmental Sciences, University of Tsukuba
| | | | - Iwao Ohtsu
- Graduate School of Life and Environmental Sciences, University of Tsukuba
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29
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CydDC functions as a cytoplasmic cystine reductase to sensitize Escherichia coli to oxidative stress and aminoglycosides. Proc Natl Acad Sci U S A 2020; 117:23565-23570. [PMID: 32900959 DOI: 10.1073/pnas.2007817117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
l-cysteine is the source of all bacterial sulfurous biomolecules. However, the cytoplasmic level of l-cysteine must be tightly regulated due to its propensity to reduce iron and drive damaging Fenton chemistry. It has been proposed that in Escherichia coli the component of cytochrome bd-I terminal oxidase, the CydDC complex, shuttles excessive l-cysteine from the cytoplasm to the periplasm, thereby maintaining redox homeostasis. Here, we provide evidence for an alternative function of CydDC by demonstrating that the cydD phenotype, unlike that of the bona fide l-cysteine exporter eamA, parallels that of the l-cystine importer tcyP. Chromosomal induction of eamA, but not of cydDC, from a strong pLtetO-1 promoter (Ptet) leads to the increased level of extracellular l-cysteine, whereas induction of cydDC or tcyP causes the accumulation of cytoplasmic l-cysteine. Congruently, inactivation of cydD renders cells resistant to hydrogen peroxide and to aminoglycoside antibiotics. In contrast, induction of cydDC sensitizes cells to oxidative stress and aminoglycosides, which can be suppressed by eamA overexpression. Furthermore, inactivation of the ferric uptake regulator (fur) in Ptet-cydDC or Ptet-tcyP cells results in dramatic loss of survival, whereas catalase (katG) overexpression suppresses the hypersensitivity of both strains to H2O2 These results establish CydDC as a reducer of cytoplasmic cystine, as opposed to an l-cysteine exporter, and further elucidate a link between oxidative stress, antibiotic resistance, and sulfur metabolism.
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30
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Krypotou E, Scortti M, Grundström C, Oelker M, Luisi BF, Sauer-Eriksson AE, Vázquez-Boland J. Control of Bacterial Virulence through the Peptide Signature of the Habitat. Cell Rep 2020; 26:1815-1827.e5. [PMID: 30759392 PMCID: PMC6389498 DOI: 10.1016/j.celrep.2019.01.073] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/09/2018] [Accepted: 01/17/2019] [Indexed: 12/20/2022] Open
Abstract
To optimize fitness, pathogens selectively activate their virulence program upon host entry. Here, we report that the facultative intracellular bacterium Listeria monocytogenes exploits exogenous oligopeptides, a ubiquitous organic N source, to sense the environment and control the activity of its virulence transcriptional activator, PrfA. Using a genetic screen in adsorbent-treated (PrfA-inducing) medium, we found that PrfA is functionally regulated by the balance between activating and inhibitory nutritional peptides scavenged via the Opp transport system. Activating peptides provide essential cysteine precursor for the PrfA-inducing cofactor glutathione (GSH). Non-cysteine-containing peptides cause promiscuous PrfA inhibition. Biophysical and co-crystallization studies reveal that peptides inhibit PrfA through steric blockade of the GSH binding site, a regulation mechanism directly linking bacterial virulence and metabolism. L. monocytogenes mutant analysis in macrophages and our functional data support a model in which changes in the balance of antagonistic Opp-imported oligopeptides promote PrfA induction intracellularly and PrfA repression outside the host. Listeria PrfA virulence regulation is controlled by antagonistic nutritional peptides Opp-imported peptides regulate PrfA upstream of the activating cofactor GSH PrfA is activated by peptides that provide essential cysteine for GSH biosynthesis Blockade of PrfA’s GSH binding site by peptides inhibits virulence gene activation
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Affiliation(s)
- Emilia Krypotou
- Microbial Pathogenesis Group, Infection Medicine, Edinburgh Medical School (Biomedical Sciences) and The Roslin Institute, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Mariela Scortti
- Microbial Pathogenesis Group, Infection Medicine, Edinburgh Medical School (Biomedical Sciences) and The Roslin Institute, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Christin Grundström
- Department of Chemistry and Umeå Centre for Microbial Research, Umeå University, 901 87 Umeå, Sweden
| | - Melanie Oelker
- Department of Chemistry and Umeå Centre for Microbial Research, Umeå University, 901 87 Umeå, Sweden
| | - Ben F Luisi
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | | | - José Vázquez-Boland
- Microbial Pathogenesis Group, Infection Medicine, Edinburgh Medical School (Biomedical Sciences) and The Roslin Institute, University of Edinburgh, Edinburgh EH16 4SB, UK.
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31
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Choo K, Kim M, Nansa SA, Bae MK, Lee C, Lee SJ. Redox potential change by the cystine importer affected on enzymatic antioxidant protection in Deinococcus geothermalis. Antonie van Leeuwenhoek 2020; 113:779-790. [PMID: 31993844 DOI: 10.1007/s10482-020-01388-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 01/21/2020] [Indexed: 10/25/2022]
Abstract
Radiation resistant bacteria genus Deinococcus species were well studied on DNA repair and anti-oxidative stress response mechanisms. There are many protection factors as enzymatic and nonenzymatic involved. One of them is intracellular redox potential as like thiol compounds including cysteine acts as primary protectant against oxidation stress. A gene cluster consisting of the genes Dgeo_1986 and Dgeo_1987 of Deinococcus geothermalis was identified as a cystine importer. The expression levels of dgeo_1986 and dgeo_1987 were up-regulated by over 60-fold and 4-fold during the late exponential (L) growth phase, respectively. The double-knockout mutant of dgeo_1986 and dgeo_1987 was reduced in cystine and thiol concentrations and leading to enhanced sensitivity against H2O2 stress. The expression of catalase (Dgeo_2728) as an enzymatic anti-oxidant is more induced in the wild-type strain than the Δdgeo_1986-87 strain at the late growth phase. The expression level of the oxidative stress response regulator OxyR (Dgeo_1888) is dependent on the intracellular redox balance. That is, when the intracellular thiol content was reduced in the wild-type strain during the L phase, OxyR was clearly induced. Interestingly, the expression level of OxyR was higher in the Δdgeo_1986-87 strain than in the wild-type strain upon H2O2 treatment. Although OxyR was induced by H2O2 treatment in Δdgeo_1986-87 strain, where intracellular redox potential of cystine was reduced as a thiol compound due to reduced cystine import, the relative level of expression of catalase was unexpectedly down-regulated. Therefore, the catalase induction system as an enzymatic antioxidant protection should be affected via the cystine importer but not rely on the OxyR controlled manner.
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Affiliation(s)
- Kyungsil Choo
- Department of Biology, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Korea
| | - Minwook Kim
- Department of Biology, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Korea.,Department of Developmental Biology, Pittsburgh Liver Research Center, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, 15260, USA
| | - Sama Abdi Nansa
- Department of Biology, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Korea
| | - Min K Bae
- Department of Biology, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Korea
| | - Chanjae Lee
- Department of Biology, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Korea
| | - Sung-Jae Lee
- Department of Biology, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Korea.
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32
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Riboflavin Plays a Pivotal Role in the UVA-Induced Cytotoxicity of Fibroblasts as a Key Molecule in the Production of H 2O 2 by UVA Radiation in Collaboration with Amino Acids and Vitamins. Int J Mol Sci 2020; 21:ijms21020554. [PMID: 31952279 PMCID: PMC7013916 DOI: 10.3390/ijms21020554] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 01/13/2020] [Accepted: 01/13/2020] [Indexed: 12/25/2022] Open
Abstract
To investigate environmental factors that contribute to ultraviolet A (UVA)-induced oxidative stress, which accelerates the senescence and toxicity of skin cells, we irradiated human fibroblasts cultured in commonly used essential media with UVA and evaluated their viability and production of reactive oxygen species. The viability of fibroblasts exposed to a single dose of 3.6 J/cm2 UVA was not reduced when cultured in Hanks balanced salt solution, but it was significantly decreased when cultured in Dulbecco’s modified Eagle’s medium (DMEM), which contains various amino acids and vitamins. Furthermore, cell viability was not reduced when fibroblasts were cultured in DMEM and treated with a hydrogen peroxide (H2O2) scavenger such as glutathione or catalase added after UVA irradiation. In addition, we confirmed that the production of H2O2 was dramatically increased by UVA photosensitization when riboflavin (R) coexisted with amino acids such as tryptophan (T), and found that R with folic acid (F) produced high levels of H2O2 after UVA irradiation. Furthermore, we noticed that R and F or R and T have different photosensitization mechanisms since NaN3, which is a singlet oxygen quencher, suppressed only R and T photosensitization. Lastly, we examined the effects of antioxidants (L-ascorbic acid, trolox, L-cysteine, and L-histidine), which are singlet oxygen or superoxide or H2O2 scavengers, on R and F or on R and T photosensitization, and found that 1 mM ascorbic acid, Trolox, and L-histidine were strongly photosensitized with R, and produced significant levels of H2O2 during UVA exposure. However, 1 mM L-cysteine dramatically suppressed H2O2 production by UVA photosensitization. These data suggest that a low concentration of R-derived photosensitization is elicited by different mechanisms depending on the coexisting vitamins and amino acids, and regulates cellular oxidative stress by producing H2O2 during UVA exposure.
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33
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Korshunov S, Imlay KRC, Imlay JA. Cystine import is a valuable but risky process whose hazards Escherichia coli minimizes by inducing a cysteine exporter. Mol Microbiol 2019; 113:22-39. [PMID: 31612555 PMCID: PMC7007315 DOI: 10.1111/mmi.14403] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2019] [Indexed: 12/24/2022]
Abstract
The structure of free cysteine makes it vulnerable to oxidation by molecular oxygen; consequently, organisms that live in oxic habitats have acquired the ability to import cystine as a sulfur source. We show that cystine imported into Escherichia coli can transfer disulfide bonds to cytoplasmic proteins. To minimize this problem, the imported cystine is rapidly reduced. However, this conversion of cystine to cysteine precludes product inhibition of the importer, so cystine import continues into cells that are already sated with cysteine. The burgeoning cysteine pool is itself hazardous, as cysteine promotes the formation of reactive oxygen species, triggers sulfide production and competitively inhibits a key enzyme in the isoleucine biosynthetic pathway. The Lrp transcription factor senses the excess cysteine and induces AlaE, an export protein that pumps cysteine back out of the cell until transcriptional controls succeed in lowering the amount of the importer. While it lasts, the overall phenomenon roughly doubles the NADPH demand of the cell. It comprises another example of the incompatibility of the reduced cytoplasms of microbes with the oxic world in which they dwell. It also reveals one natural source of cytoplasmic disulfide stress and sheds light on a role for broad-spectrum amino acid exporters.
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Affiliation(s)
- Sergey Korshunov
- Department of Microbiology, University of Illinois, Urbana, IL, 61801, USA
| | | | - James A Imlay
- Department of Microbiology, University of Illinois, Urbana, IL, 61801, USA
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34
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Smirnova GV, Tyulenev AV, Bezmaternykh KV, Muzyka NG, Ushakov VY, Oktyabrsky ON. Cysteine homeostasis under inhibition of protein synthesis in Escherichia coli cells. Amino Acids 2019; 51:1577-1592. [PMID: 31617110 DOI: 10.1007/s00726-019-02795-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 10/02/2019] [Indexed: 01/23/2023]
Abstract
Increased intracellular cysteine poses a potential danger to cells due to the high ability of cysteine to reduce free iron and promote the Fenton reaction. Here, we studied ways to maintain cysteine homeostasis in E. coli cells while inhibiting protein synthesis with valine or chloramphenicol. When growing wild-type bacteria on minimal medium with sulfate, an excess of cysteine resulting from the inhibition of protein synthesis is mainly incorporated into glutathione (up to 90%), which, therefore, can be considered as cysteine buffer. The share of hydrogen sulfide, which is the product of cysteine degradation by cysteine synthase B (CysM), does not exceed 1-3%, the rest falls on free cysteine, exported from cells. As a result, intracellular free cysteine is maintained at a low level (about 0.1 mM). The lack of glutathione in the gshA mutant increases H2S production and excretion of cysteine and leads to a threefold increase in the level of intracellular cysteine in response to valine and chloramphenicol. The relA mutants, exposed to valine, produce more H2S, dramatically accelerate the export of glutathione and accumulate more cysteine in the cytoplasm than their parent, which indicates that the regulatory nucleotide (p)ppGpp is involved in maintaining cysteine homeostasis. Disruption of cysteine homeostasis in gshA and relA mutants increases their sensitivity to peroxide stress.
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Affiliation(s)
- Galina V Smirnova
- Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Golev Street 13, 614081, Perm, Russia.
| | - Aleksey V Tyulenev
- Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Golev Street 13, 614081, Perm, Russia
| | - Kseniya V Bezmaternykh
- Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Golev Street 13, 614081, Perm, Russia
| | - Nadezda G Muzyka
- Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Golev Street 13, 614081, Perm, Russia
| | - Vadim Y Ushakov
- Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Golev Street 13, 614081, Perm, Russia.,Perm State University, Bukireva Street 15, 614990, Perm, Russia
| | - Oleg N Oktyabrsky
- Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, Golev Street 13, 614081, Perm, Russia.,Perm National Research Polytechnic University, Komsomolsky Pr. 29, 614990, Perm, Russia
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35
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Upregulation of PBP1B and LpoB in cysB Mutants Confers Mecillinam (Amdinocillin) Resistance in Escherichia coli. Antimicrob Agents Chemother 2019; 63:AAC.00612-19. [PMID: 31332059 PMCID: PMC6761508 DOI: 10.1128/aac.00612-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 07/12/2019] [Indexed: 11/20/2022] Open
Abstract
Mecillinam (amdinocillin) is a β-lactam antibiotic that inhibits the essential penicillin-binding protein 2 (PBP2). In clinical isolates of Escherichia coli from urinary tract infections, inactivation of the cysB gene (which encodes the main regulator of cysteine biosynthesis, CysB) is the major cause of resistance. How a nonfunctional CysB protein confers resistance is unknown, however, and in this study we wanted to examine the mechanism of resistance. Mecillinam (amdinocillin) is a β-lactam antibiotic that inhibits the essential penicillin-binding protein 2 (PBP2). In clinical isolates of Escherichia coli from urinary tract infections, inactivation of the cysB gene (which encodes the main regulator of cysteine biosynthesis, CysB) is the major cause of resistance. How a nonfunctional CysB protein confers resistance is unknown, however, and in this study we wanted to examine the mechanism of resistance. Results show that cysB mutations cause a gene regulatory response that changes the expression of ∼450 genes. Among the proteins that show increased levels are the PBP1B, LpoB, and FtsZ proteins, which are known to be involved in peptidoglycan biosynthesis. Artificial overexpression of either PBP1B or LpoB in a wild-type E. coli strain conferred mecillinam resistance; conversely, inactivation of either the mrcB gene (which encodes PBP1B) or the lpoB gene (which encodes the PBP1B activator LpoB) made cysB mutants susceptible. These results show that expression of the proteins PBP1B and LpoB is both necessary and sufficient to confer mecillinam resistance. The addition of reducing agents to a cysB mutant converted it to full susceptibility, with associated downregulation of PBP1B, LpoB, and FtsZ. We propose a model in which cysB mutants confer mecillinam resistance by inducing a response that causes upregulation of the PBP1B and LpoB proteins. The higher levels of these two proteins can then rescue cells with mecillinam-inhibited PBP2. Our results also show how resistance can be modulated by external conditions such as reducing agents.
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36
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Poole RK, Cozens AG, Shepherd M. The CydDC family of transporters. Res Microbiol 2019; 170:407-416. [PMID: 31279084 DOI: 10.1016/j.resmic.2019.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 06/12/2019] [Accepted: 06/25/2019] [Indexed: 12/23/2022]
Abstract
The CydDC family of ABC transporters export the low molecular weight thiols glutathione and cysteine to the periplasm of a variety of bacterial species. The CydDC complex has previously been shown to be important for disulfide folding, motility, respiration, and tolerance to nitric oxide and antibiotics. In addition, CydDC is thus far unique amongst ABC transporters in that it binds a haem cofactor that appears to modulate ATPase activity. CydDC has a diverse impact upon bacterial metabolism, growth, and virulence, and is of interest to those working on membrane transport mechanisms, redox biology, aerobic respiration, and stress sensing/tolerance during infection.
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Affiliation(s)
- Robert K Poole
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Sheffield, United Kingdom
| | - Adam G Cozens
- School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Mark Shepherd
- School of Biosciences, University of Kent, Canterbury, United Kingdom.
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Kawano Y, Shiroyama M, Kanazawa K, Suzuki YA, Ohtsu I. Development of high-throughput quantitative analytical method for L-cysteine-containing dipeptides by LC-MS/MS toward its fermentative production. AMB Express 2019; 9:91. [PMID: 31227937 PMCID: PMC6588663 DOI: 10.1186/s13568-019-0817-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 06/15/2019] [Indexed: 11/23/2022] Open
Abstract
l-Cysteine (Cys) is metabolically fundamental sulfur compound and important components in various cellular factors. Interestingly, free-form Cys itself as a simple monomeric amino acid was recently shown to function in a novel antioxidative system (cysteine/cystine shuttle system) in Escherichia coli. However, as for Cys-containing dipeptides, the biological functions, effects, and even contents have still remained largely elusive. The potential functions should be a part of cellular redox system and important in basic and applied biology. For its progress, establishment of reliable quantitation method is the first. However, such accurate analysis is unexpectedly difficult even in Cys, because thiol compounds convert through disulfide-exchange and air oxidation during sample preparation. Addressing this problem, in this study, thiol molecules like Cys-containing dipeptides were derivatized by using monobromobimane (thiol-specific alkylating reagent) and detected as S-bimanyl derivatives by liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). Sample separation was processed with a C18 column (2.1 mm × 150 mm, 1.7 μm) and with water-acetonitrile gradient mobile phase containing 0.1% (v/v) formic acid at flow rate of 0.25 ml/min. The mass spectrometer was operated in the multiple reaction monitoring in positive/negative mode with electrospray ionization. The derivatization could indeed avoid the unfavorable reactions, namely, developed the method reflecting their correct contents on sampling. Furthermore, the method was successfully applied to monitoring Cys-containing dipeptides in E. coli Cys producer overexpressing bacD gene. This is the first report of the quantitative analysis of Cys-containing dipeptides, which should be useful for further study of fermentative production of Cys-containing dipeptides.
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Keasey SL, Suh MJ, Das S, Blancett CD, Zeng X, Andresson T, Sun MG, Ulrich RG. Decreased Antibiotic Susceptibility Driven by Global Remodeling of the Klebsiella pneumoniae Proteome. Mol Cell Proteomics 2019; 18:657-668. [PMID: 30617156 PMCID: PMC6442359 DOI: 10.1074/mcp.ra118.000739] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 01/04/2019] [Indexed: 12/04/2022] Open
Abstract
Bacteria can circumvent the effect of antibiotics by transitioning to a poorly understood physiological state that does not involve conventional genetic elements of resistance. Here we examine antibiotic susceptibility with a Class A β-lactamase+ invasive strain of Klebsiella pneumoniae that was isolated from a lethal outbreak within laboratory colonies of Chlorocebus aethiops sabaeus monkeys. Bacterial responses to the ribosomal synthesis inhibitors streptomycin and doxycycline resulted in distinct proteomic adjustments that facilitated decreased susceptibility to each antibiotic. Drug-specific changes to proteomes included proteins for receptor-mediated membrane transport and sugar utilization, central metabolism, and capsule production, whereas mechanisms common to both antibiotics included elevated scavenging of reactive oxygen species and turnover of misfolded proteins. Resistance to combined antibiotics presented integrated adjustments to protein levels as well as unique drug-specific proteomic features. Our results demonstrate that dampening of Klebsiella pneumoniae susceptibility involves global remodeling of the bacterial proteome to counter the effects of antibiotics and stabilize growth.
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Affiliation(s)
- Sarah L Keasey
- From the ‡Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland;; Molecular and Translational Sciences Division, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Moo-Jin Suh
- Molecular and Translational Sciences Division, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Sudipto Das
- Laboratory of Proteomics and Analytical Technologies, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, NCI-Frederick, Frederick, Maryland
| | - Candace D Blancett
- Pathology Division, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Xiankun Zeng
- Pathology Division, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Thorkell Andresson
- Laboratory of Proteomics and Analytical Technologies, Leidos Biomedical Research, Frederick National Laboratory for Cancer Research, NCI-Frederick, Frederick, Maryland
| | - Mei G Sun
- Pathology Division, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Robert G Ulrich
- Molecular and Translational Sciences Division, U.S. Army Medical Research Institute of Infectious Diseases, Frederick, Maryland;.
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39
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Li K, Xin Y, Xuan G, Zhao R, Liu H, Xia Y, Xun L. Escherichia coli Uses Separate Enzymes to Produce H 2S and Reactive Sulfane Sulfur From L-cysteine. Front Microbiol 2019; 10:298. [PMID: 30873134 PMCID: PMC6401616 DOI: 10.3389/fmicb.2019.00298] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 02/04/2019] [Indexed: 11/28/2022] Open
Abstract
Hydrogen sulfide (H2S) has been proposed to have various physiological functions, and it may function through reactive sulfane sulfur. Since the two sulfur forms often coexist, they are normally considered interchangeable. Here, we characterized the production of H2S and reactive sulfane sulfur in Escherichia coli MG1655 and found that they are not readily interchangeable. They are primarily produced from L-cysteine via different enzymes. L-Cysteine desulfhydrases consumed L-cysteine and directly generated H2S. The produced H2S was mainly lost through evaporation into the gas phase, as E. coli does not have enzymes that easily oxidize H2S to reactive sulfane sulfur. L-Cysteine desulfhydrases were also responsible for the degradation of exogenous L-cysteine, which is toxic at high levels. Conversely, L-cysteine aminotransferase and 3-mercaptopyruvate sulfurtransferase sequentially metabolized endogenous L-cysteine to produce cellular reactive sulfane sulfur; however, it was not a major route of H2S production during normal growth or during the metabolism of exogenous L-cysteine by the resting cells. Noticeably, the 3-mercaptopyruvate sulfurtransferase mutant contained less reactive sulfane sulfur and displayed a greater sensitivity to H2O2 than did the wild type. Thence, reactive sulfane sulfur is likely a common cellular component, involved in protein sulfhydration and protecting cells from oxidative stress.
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Affiliation(s)
- Kai Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yufeng Xin
- College of Life Sciences, Qufu Normal University, Qufu, China
| | - Guanhua Xuan
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Rui Zhao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Huaiwei Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yongzhen Xia
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Luying Xun
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
- School of Molecular Biosciences, Washington State University, Pullman, WA, United States
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Takagi H. Metabolic regulatory mechanisms and physiological roles of functional amino acids and their applications in yeast. Biosci Biotechnol Biochem 2019; 83:1449-1462. [PMID: 30712454 DOI: 10.1080/09168451.2019.1576500] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In yeast, amino acid metabolism and its regulatory mechanisms vary under different growth environments by regulating anabolic and catabolic processes, including uptake and export, and the metabolic styles form a complicated but robust network. There is also crosstalk with various metabolic pathways, products and signal molecules. The elucidation of metabolic regulatory mechanisms and physiological roles is important fundamental research for understanding life phenomenon. In terms of industrial application, the control of amino acid composition and content is expected to contribute to an improvement in productivity, and to add to the value of fermented foods, alcoholic beverages, bioethanol, and other valuable compounds (proteins and amino acids, etc.). This review article mainly describes our research in constructing yeast strains with high functionality, focused on the metabolic regulatory mechanisms and physiological roles of "functional amino acids", such as l-proline, l-arginine, l-leucine, l-valine, l-cysteine, and l-methionine, found in yeast.
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Affiliation(s)
- Hiroshi Takagi
- a Division of Biological Science, Graduate School of Science and Technology , Nara Institute of Science and Technology , Nara , Japan
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41
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Redox poise and metabolite changes in bread wheat seeds are advanced by priming with hot steam. Biochem J 2018; 475:3725-3743. [PMID: 30401685 DOI: 10.1042/bcj20180632] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/24/2018] [Accepted: 11/02/2018] [Indexed: 12/20/2022]
Abstract
Fast and uniform germination is key to agricultural production and can be achieved by seed 'priming' techniques. Here, we characterised the responses of bread wheat (Triticum aestivum L.) seeds to a hot steam treatment ('BioFlash'), which accelerated water uptake, resulting in faster germination and seedling growth, typical traits of primed seed. Before the completion of germination, metabolite profiling of seeds revealed advanced accumulation of several amino acids (especially cysteine and serine), sugars (ribose, glucose), and organic acids (glycerate, succinate) in hot steam-treated seeds, whereas sugar alcohols (e.g. arabitol, mannitol) and trehalose decreased in all seeds. Tocochromanols (the 'vitamin E family') rose independently of the hot steam treatment. We further assessed shifts in the half-cell reduction potentials of low-molecular-weight (LMW) thiol-disulfide redox couples [i.e. glutathione disulfide (GSSG)/glutathione (GSH) and cystine/cysteine], alongside the activities of the reactive oxygen species (ROS)-processing enzyme superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase. Upon the first 4 h of imbibition, a rapid conversion of LMW disulfides to thiols occurred. Completion of germination was associated with a re-oxidation of the LMW thiol-disulfide cellular redox environment, before more reducing conditions were re-established during seedling growth, accompanied by an increase in all ROS-processing enzyme activities. Furthermore, changes in the thiol-disulfide cellular redox state were associated to specific stages of wheat seed germination. In conclusion, the priming effect of the hot steam treatment advanced the onset of seed metabolism, including redox shifts associated with germination and seedling growth.
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Seregina TA, Nagornykh MO, Lobanov KV, Shakulov RS, Mironov AS. The New Role of СysB Transcription Factor in Cysteine Degradation and Production of Hydrogen Sulfide in E. coli. RUSS J GENET+ 2018. [DOI: 10.1134/s1022795418110145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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43
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Kawano Y, Suzuki K, Ohtsu I. Current understanding of sulfur assimilation metabolism to biosynthesize L-cysteine and recent progress of its fermentative overproduction in microorganisms. Appl Microbiol Biotechnol 2018; 102:8203-8211. [PMID: 30046857 DOI: 10.1007/s00253-018-9246-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/12/2018] [Accepted: 07/13/2018] [Indexed: 12/01/2022]
Abstract
To all organisms, sulfur is an essential and important element. The assimilation of inorganic sulfur molecules such as sulfate and thiosulfate into organic sulfur compounds such as L-cysteine and L-methionine (essential amino acid for human) is largely contributed by microorganisms. Of these, special attention is given to thiosulfate (S2O32-) assimilation, because thiosulfate relative to often utilized sulfate (SO42-) as a sulfur source is proposed to be more advantageous in microbial growth and biotechnological applications like L-cysteine fermentative overproduction toward industrial manufacturing. In Escherichia coli as well as other many bacteria, the thiosulfate assimilation pathway is known to depend on O-acetyl-L-serine sulfhydrylase B. Recently, another yet-unidentified CysM-independent thiosulfate pathway was found in E. coli. This pathway is expected to consist of the initial part of the thiosulfate to sulfite (SO32-) conversion, and the latter part might be shared with the final part of the known sulfate assimilation pathway [sulfite → sulfide (S2-) → L-cysteine]. The catalysis of thiosulfate to sulfite is at least partly mediated by thiosulfate sulfurtransferase (GlpE). In this mini-review, we introduce updated comprehensive information about sulfur assimilation in microorganisms, including this topic. Also, we introduce recent advances of the application study about L-cysteine overproduction, including the GlpE overexpression.
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Affiliation(s)
- Yusuke Kawano
- Innovation Medical Research Institute, University of Tsukuba, Tsukuba, Japan
| | - Kengo Suzuki
- Department of Research and Development, Euglena Co., Ltd., Minato-ku, Tokyo, Japan
| | - Iwao Ohtsu
- Innovation Medical Research Institute, University of Tsukuba, Tsukuba, Japan.
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Tyulenev A, Smirnova G, Muzyka N, Ushakov V, Oktyabrsky O. The role of sulfides in stress-induced changes of Eh in Escherichia coli cultures. Bioelectrochemistry 2018; 121:11-17. [DOI: 10.1016/j.bioelechem.2017.12.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 12/06/2017] [Accepted: 12/22/2017] [Indexed: 11/25/2022]
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45
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Nonaka G, Takumi K. Cysteine degradation gene yhaM, encoding cysteine desulfidase, serves as a genetic engineering target to improve cysteine production in Escherichia coli. AMB Express 2017; 7:90. [PMID: 28488255 PMCID: PMC5423876 DOI: 10.1186/s13568-017-0389-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 04/21/2017] [Indexed: 11/16/2022] Open
Abstract
Cysteine is an important amino acid for various industries; however, there is no efficient microbial fermentation-based production method available. Owing to its cytotoxicity, bacterial intracellular levels of cysteine are stringently controlled via several modes of regulation, including cysteine degradation by cysteine desulfhydrases and cysteine desulfidases. In Escherichia coli, several metabolic enzymes are known to exhibit cysteine degradative activities, however, their specificity and physiological significance for cysteine detoxification via degradation are unclear. Relaxing the strict regulation of cysteine is crucial for its overproduction; therefore, identifying and modulating the major degradative activity could facilitate the genetic engineering of a cysteine-producing strain. In the present study, we used genetic screening to identify genes that confer cysteine resistance in E. coli and we identified yhaM, which encodes cysteine desulfidase and decomposes cysteine into hydrogen sulfide, pyruvate, and ammonium. Phenotypic characterization of a yhaM mutant via growth under toxic concentrations of cysteine followed by transcriptional analysis of its response to cysteine showed that yhaM is cysteine-inducible, and its physiological role is associated with resisting the deleterious effects of cysteine in E. coli. In addition, we confirmed the effects of this gene on the fermentative production of cysteine using E. coli-based cysteine-producing strains. We propose that yhaM encodes the major cysteine-degrading enzyme and it has the most significant role in cysteine detoxification among the numerous enzymes reported in E. coli, thereby providing a core target for genetic engineering to improve cysteine production in this bacterium.
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46
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Neal SE, Dabir DV, Wijaya J, Boon C, Koehler CM. Osm1 facilitates the transfer of electrons from Erv1 to fumarate in the redox-regulated import pathway in the mitochondrial intermembrane space. Mol Biol Cell 2017; 28:2773-2785. [PMID: 28814504 PMCID: PMC5638582 DOI: 10.1091/mbc.e16-10-0712] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 08/10/2017] [Accepted: 08/10/2017] [Indexed: 11/18/2022] Open
Abstract
Osm1 transfers electrons from fumarate to succinate and functions with Mia40 and Erv1 in the redox-regulated import pathway for proteins that form disulfide bonds in the mitochondrial intermembrane space. Expression of Osm1 and cytochrome c is reciprocally regulated, indicating that the cell has strategies to coordinate expression of terminal electron acceptors. Prokaryotes have aerobic and anaerobic electron acceptors for oxidative folding of periplasmic proteins. The mitochondrial intermembrane space has an analogous pathway with the oxidoreductase Mia40 and sulfhydryl oxidase Erv1, termed the mitochondrial intermembrane space assembly (MIA) pathway. The aerobic electron acceptors include oxygen and cytochrome c, but an acceptor that can function under anaerobic conditions has not been identified. Here we show that the fumarate reductase Osm1, which facilitates electron transfer from fumarate to succinate, fills this gap as a new electron acceptor. In addition to microsomes, Osm1 localizes to the mitochondrial intermembrane space and assembles with Erv1 in a complex. In reconstitution studies with reduced Tim13, Mia40, and Erv1, the addition of Osm1 and fumarate completes the disulfide exchange pathway that results in Tim13 oxidation. From in vitro import assays, mitochondria lacking Osm1 display decreased import of MIA substrates, Cmc1 and Tim10. Comparative reconstitution assays support that the Osm1/fumarate couple accepts electrons with similar efficiency to cytochrome c and that the cell has strategies to coordinate expression of the terminal electron acceptors. Thus Osm1/fumarate is a new electron acceptor couple in the mitochondrial intermembrane space that seems to function in both aerobic and anaerobic conditions.
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Affiliation(s)
- Sonya E Neal
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095
| | - Deepa V Dabir
- Department of Biology, Loyola Marymount University, Los Angeles, CA 90045
| | - Juwina Wijaya
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Cennyana Boon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095
| | - Carla M Koehler
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095 .,Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095.,Jonsson Comprehensive Cancer Center, University of California, Los Angeles, Los Angeles, CA 90095
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47
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Cossu A, Dou F, Young GM, Nitin N. Biomarkers of oxidative damage in bacteria for the assessment of sanitation efficacy in lettuce wash water. Appl Microbiol Biotechnol 2017; 101:5365-5375. [PMID: 28508923 DOI: 10.1007/s00253-017-8314-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 04/24/2017] [Accepted: 04/28/2017] [Indexed: 11/28/2022]
Abstract
In the fresh produce industry, validation of sanitation efficacy is critical to prevent cross-contamination of produce. The current validation approaches are either based on time-consuming plate counting assays or indirect measurements of chemical properties of wash water. In the study, the focus was to identify biomarkers that can provide direct assessment of oxidative damage in bacteria upon exposure to sanitizers in the presence of fresh produce and correlation of these oxidative biomarkers with logarithmic inactivation of bacteria. Two endogenous bacterial biomarkers, protein carbonylation and thiol oxidation, were evaluated for assessing oxidative damage in Escherichia coli O157:H7 and Listeria innocua during sanitation of pre-cut lettuce leaves with NaOCl or H2O2. Results show that NaOCl treatment was more effective than H2O2 for oxidation of both the intracellular thiols and protein carbonylation in the selected strains. Statistical analysis of the measurements illustrates that oxidation of the intracellular thiol induced by NaOCl or H2O2 was correlated with logarithmic reduction of E. coli O157:H7 and L. innocua. In contrast, changes in the protein carbonylation content were not correlated with reduction in bacterial cell viability. In summary, these results provide a novel approach to validate sanitation efficacy for the fresh produce industry.
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Affiliation(s)
- Andrea Cossu
- Department of Food Science and Technology, University of California, Davis, Robert Mondavi Institute South, 392 Old Davis Road, Davis, CA, 95616, USA
| | - Fang Dou
- Department of Food Science and Technology, University of California, Davis, Robert Mondavi Institute South, 392 Old Davis Road, Davis, CA, 95616, USA
| | - Glenn M Young
- Department of Food Science and Technology, University of California, Davis, Robert Mondavi Institute South, 392 Old Davis Road, Davis, CA, 95616, USA
| | - Nitin Nitin
- Department of Food Science and Technology, University of California, Davis, Robert Mondavi Institute South, 392 Old Davis Road, Davis, CA, 95616, USA.
- Department of Biological and Agricultural Engineering, University of California, Davis, Davis, CA, 95616, USA.
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48
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Gerna D, Roach T, Stöggl W, Wagner J, Vaccino P, Limonta M, Kranner I. Changes in low-molecular-weight thiol-disulphide redox couples are part of bread wheat seed germination and early seedling growth. Free Radic Res 2017; 51:568-581. [PMID: 28580817 DOI: 10.1080/10715762.2017.1338344] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The tripeptide antioxidant glutathione (γ-l-glutamyl-l-cysteinyl-glycine; GSH) essentially contributes to thiol-disulphide conversions, which are involved in the control of seed development, germination, and seedling establishment. However, the relative contribution of GSH metabolism in different seed structures is not fully understood. We studied the GSH/glutathione disulphide (GSSG) redox couple and associated low-molecular-weight (LMW) thiols and disulphides related to GSH metabolism in bread wheat (Triticum aestivum L.) seeds, focussing on redox changes in the embryo and endosperm during germination. In dry seeds, GSH was the predominant LMW thiol and, 15 h after the onset of imbibition, embryos of non-germinated seeds contained 12 times more LMW thiols than the endosperm. In germinated seeds, the embryo contained 17 and 11 times more LMW thiols than the endosperm after 15 and 48 h, respectively. This resulted in the embryo having significantly more reducing half-cell reduction potentials of GSH/GSSG and cysteine (Cys)/cystine (CySS) redox couples (EGSSG/2GSH and ECySS/2Cys, respectively). Upon seed germination and early seedling growth, Cys and CySS concentrations significantly increased in both embryo and endosperm, progressively contributing to the cellular LMW thiol-disulphide redox environment (Ethiol-disulphide). The changes in ECySS/2Cys could be related to the mobilisation of storage proteins in the endosperm during early seedling growth. We suggest that EGSSG/2GSH and ECySS/2Cys can be used as markers of the physiological and developmental stage of embryo and endosperm. We also present a model of interaction between LMW thiols and disulphides with hydrogen peroxide (H2O2) in redox regulation of bread wheat germination and early seedling growth.
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Affiliation(s)
- Davide Gerna
- a Department of Botany , Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innsbruck , Austria
| | - Thomas Roach
- a Department of Botany , Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innsbruck , Austria
| | - Wolfgang Stöggl
- a Department of Botany , Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innsbruck , Austria
| | - Johanna Wagner
- a Department of Botany , Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innsbruck , Austria
| | - Patrizia Vaccino
- b Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria , Research Unit for Cereal Selection in Continental Areas, S . Angelo Lodigiano , Italy
| | - Margherita Limonta
- b Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria , Research Unit for Cereal Selection in Continental Areas, S . Angelo Lodigiano , Italy
| | - Ilse Kranner
- a Department of Botany , Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innsbruck , Austria
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49
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Nagy YI, Hussein MMM, Ragab YM, Attia AS. Isogenic mutations in the Moraxella catarrhalis CydDC system display pleiotropic phenotypes and reveal the role of a palindrome sequence in its transcriptional regulation. Microbiol Res 2017. [PMID: 28647125 DOI: 10.1016/j.micres.2017.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Moraxella catarrhalis is becoming an important human respiratory tract pathogen affecting significant proportions from the population. However, still little is known about its physiology and molecular regulation. To this end, the CydDC, which is a heterodimeric ATP binding cassette transporter that has been shown to contribute to the maintenance of the redox homeostasis across the periplasm in other Gram-negative bacteria, is studied here. Amino acids multiple sequence alignments indicated that M. catarrhalis CydC is different from the CydC proteins of the bacterial species in which this system has been previously studied. These findings prompted further interest in studying this system in M. catarrhalis. Isogenic mutant in the CydDC system showed suppression in growth rate, hypersensitivity to oxidative and reductive stress and increased accumulation of intracellular cysteine levels. In addition, the growth of cydC- mutant exhibited hypersensitivity to exogenous cysteine; however, it did not display a significant difference from its wild-type counterpart in the murine pulmonary clearance model. Moreover, a palindrome was detected 94bp upstream of the cydD ORF suggesting it might act as a potential regulatory element. Real-time reverse transcription-PCR analysis showed that deletion/change in the palindrome resulted into alterations in the transcription levels of cydC. A better understanding of such system and its regulation helps in developing better ways to combat M. catarrhalis infections.
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Affiliation(s)
- Yosra I Nagy
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt
| | - Manal M M Hussein
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt
| | - Yasser M Ragab
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt
| | - Ahmed S Attia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, 11562, Egypt.
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50
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Mechanism of H 2S-mediated protection against oxidative stress in Escherichia coli. Proc Natl Acad Sci U S A 2017; 114:6022-6027. [PMID: 28533366 DOI: 10.1073/pnas.1703576114] [Citation(s) in RCA: 136] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Endogenous hydrogen sulfide (H2S) renders bacteria highly resistant to oxidative stress, but its mechanism remains poorly understood. Here, we report that 3-mercaptopyruvate sulfurtransferase (3MST) is the major source of endogenous H2S in Escherichia coli Cellular resistance to H2O2 strongly depends on the activity of mstA, a gene that encodes 3MST. Deletion of the ferric uptake regulator (Fur) renders ∆mstA cells hypersensitive to H2O2 Conversely, induction of chromosomal mstA from a strong pLtetO-1 promoter (P tet -mstA) renders ∆fur cells fully resistant to H2O2 Furthermore, the endogenous level of H2S is reduced in ∆fur or ∆sodA ∆sodB cells but restored after the addition of an iron chelator dipyridyl. Using a highly sensitive reporter of the global response to DNA damage (SOS) and the TUNEL assay, we show that 3MST-derived H2S protects chromosomal DNA from oxidative damage. We also show that the induction of the CysB regulon in response to oxidative stress depends on 3MST, whereas the CysB-regulated l-cystine transporter, TcyP, plays the principle role in the 3MST-mediated generation of H2S. These findings led us to propose a model to explain the interplay between l-cysteine metabolism, H2S production, and oxidative stress, in which 3MST protects E. coli against oxidative stress via l-cysteine utilization and H2S-mediated sequestration of free iron necessary for the genotoxic Fenton reaction.
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