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Sui X, Wang J, Zhao Z, Liu B, Liu M, Liu M, Shi C, Feng X, Fu Y, Shi D, Li S, Qi Q, Xian M, Zhao G. Phenolic compounds induce ferroptosis-like death by promoting hydroxyl radical generation in the Fenton reaction. Commun Biol 2024; 7:199. [PMID: 38368473 PMCID: PMC10874397 DOI: 10.1038/s42003-024-05903-5] [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: 11/05/2023] [Accepted: 02/08/2024] [Indexed: 02/19/2024] Open
Abstract
Phenolic compounds are industrially versatile chemicals, also the most ubiquitous pollutants. Recently, biosynthesis and biodegradation of phenols has attracted increasing attention, while phenols' toxicity is a major issue. Here, we evolved phloroglucinol-tolerant Escherichia coli strains via adaptive evolution, and three mutations (ΔsodB, ΔclpX and fetAB overexpression) prove of great assistance in the tolerance improvement. We discover that phloroglucinol complexes with iron and promotes the generation of hydroxyl radicals in Fenton reaction, which leads to reducing power depletion, lipid peroxidation, and ferroptosis-like cell death of E. coli. Besides phloroglucinol, various phenols can trigger ferroptosis-like death in diverse organisms, from bacteria to mammalian cells. Furthermore, repressing this ferroptosis-like death improves phloroglucinol production and phenol degradation by corresponding strains respectively, showing great application potential in microbial degradation or production of desired phenolic compounds, and phloroglucinol-induced ferroptosis suppresses tumor growth in mice, indicating phloroglucinol as a promising drug for cancer treatment.
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Affiliation(s)
- Xinyue Sui
- State Key Laboratory of Microbial Technology and Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Jichao Wang
- State Key Laboratory of Microbial Technology and Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Zhiqiang Zhao
- CAS Key Lab of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
| | - Miaomiao Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
| | - Min Liu
- State Key Laboratory of Microbial Technology and Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Cong Shi
- State Key Laboratory of Microbial Technology and Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Xinjun Feng
- CAS Key Lab of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Yingxin Fu
- State Key Laboratory of Microbial Technology and Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Dayong Shi
- State Key Laboratory of Microbial Technology and Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Shengying Li
- State Key Laboratory of Microbial Technology and Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Qingsheng Qi
- State Key Laboratory of Microbial Technology and Institute of Microbial Technology, Shandong University, Qingdao, China
| | - Mo Xian
- CAS Key Lab of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Guang Zhao
- State Key Laboratory of Microbial Technology and Institute of Microbial Technology, Shandong University, Qingdao, China.
- CAS Key Lab of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China.
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Huanca-Juarez J, Nascimento-Silva EA, Silva NH, Silva-Rocha R, Guazzaroni ME. Identification and functional analysis of novel protein-encoding sequences related to stress-resistance. Front Microbiol 2023; 14:1268315. [PMID: 37840709 PMCID: PMC10568318 DOI: 10.3389/fmicb.2023.1268315] [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: 07/27/2023] [Accepted: 08/30/2023] [Indexed: 10/17/2023] Open
Abstract
Currently, industrial bioproducts are less competitive than chemically produced goods due to the shortcomings of conventional microbial hosts. Thus, is essential developing robust bacteria for improved cell tolerance to process-specific parameters. In this context, metagenomic approaches from extreme environments can provide useful biological parts to improve bacterial robustness. Here, in order to build genetic constructs that increase bacterial resistance to diverse stress conditions, we recovered novel protein-encoding sequences related to stress-resistance from metagenomic databases using an in silico approach based on Hidden-Markov-Model profiles. For this purpose, we used metagenomic shotgun sequencing data from microbial communities of extreme environments to identify genes encoding chaperones and other proteins that confer resistance to stress conditions. We identified and characterized 10 novel protein-encoding sequences related to the DNA-binding protein HU, the ATP-dependent protease ClpP, and the chaperone protein DnaJ. By expressing these genes in Escherichia coli under several stress conditions (including high temperature, acidity, oxidative and osmotic stress, and UV radiation), we identified five genes conferring resistance to at least two stress conditions when expressed in E. coli. Moreover, one of the identified HU coding-genes which was retrieved from an acidic soil metagenome increased E. coli tolerance to four different stress conditions, implying its suitability for the construction of a synthetic circuit directed to expand broad bacterial resistance.
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Affiliation(s)
- Joshelin Huanca-Juarez
- Department of Cell and Molecular Biology, Ribeirão Preto School of Medicine (FMRP) – University of São Paulo (USP), São Paulo, Brazil
- Department of Biology, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto (FFCLRP) – University of São Paulo (USP), São Paulo, Brazil
| | - Edson Alexandre Nascimento-Silva
- Department of Cell and Molecular Biology, Ribeirão Preto School of Medicine (FMRP) – University of São Paulo (USP), São Paulo, Brazil
- Department of Biology, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto (FFCLRP) – University of São Paulo (USP), São Paulo, Brazil
| | - Ninna Hirata Silva
- Department of Cell and Molecular Biology, Ribeirão Preto School of Medicine (FMRP) – University of São Paulo (USP), São Paulo, Brazil
| | | | - María-Eugenia Guazzaroni
- Department of Biology, Faculty of Philosophy, Sciences and Letters of Ribeirão Preto (FFCLRP) – University of São Paulo (USP), São Paulo, Brazil
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Chen L, Liu R, Li S, Wu M, Yu H, Ge Q. Metabolism of hydrogen peroxide by Lactobacillus plantarum NJAU-01: A proteomics study. Food Microbiol 2023; 112:104246. [PMID: 36906310 DOI: 10.1016/j.fm.2023.104246] [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: 10/31/2022] [Revised: 02/08/2023] [Accepted: 02/22/2023] [Indexed: 02/25/2023]
Abstract
This study aimed to investigate the time-course effect of Lactobacillus plantarum NJAU-01 in scavenging exogenous hydrogen peroxide (H2O2). The results showed that L. plantarum NJAU-01 at 107 CFU/mL was able to eliminate a maximum of 4 mM H2O2 within a prolonged lag phase and resume to proliferate during the following culture. Redox state in the start-lag phase (0 h, without the addition of H2O2), indicated by glutathione and protein sulfhydryl, was impaired in the lag phase (3 h and 12 h) and then gradually recovered during subsequent growing stages (20 h and 30 h). By using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and proteomics analysis, a total of 163 proteins such as PhoP family transcriptional regulator, glutamine synthetase, peptide methionine sulfoxide reductase, thioredoxin reductase, ribosomal proteins, acetolactate synthase, ATP binding subunit ClpX, phosphoglycerate kinase, UvrABC system protein A and UvrABC system protein B were identified as differential proteins across the entire growth phase. Those proteins were mainly involved in H2O2 sensing, protein synthesis, repairing proteins and DNA lesions, amino sugar and nucleotide sugar metabolism. Our data suggest that biomolecules of L. plantarum NJAU-01 are oxidized to passively consume H2O2 and are restored by the enhanced protein and/or gene repair systems.
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Affiliation(s)
- Lei Chen
- College of Food Science and Engineering, Yangzhou University, Industrial Engineering Center for Huaiyang Cuisine of Jiangsu Province, Yangzhou, 225127, China
| | - Rui Liu
- College of Food Science and Engineering, Yangzhou University, Industrial Engineering Center for Huaiyang Cuisine of Jiangsu Province, Yangzhou, 225127, China.
| | - Suyun Li
- College of Food Science and Engineering, Yangzhou University, Industrial Engineering Center for Huaiyang Cuisine of Jiangsu Province, Yangzhou, 225127, China
| | - Mangang Wu
- College of Food Science and Engineering, Yangzhou University, Industrial Engineering Center for Huaiyang Cuisine of Jiangsu Province, Yangzhou, 225127, China
| | - Hai Yu
- College of Food Science and Engineering, Yangzhou University, Industrial Engineering Center for Huaiyang Cuisine of Jiangsu Province, Yangzhou, 225127, China
| | - Qingfeng Ge
- College of Food Science and Engineering, Yangzhou University, Industrial Engineering Center for Huaiyang Cuisine of Jiangsu Province, Yangzhou, 225127, China.
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Hou C, Liu L, Ju X, Xiao Y, Li B, You C. Revisiting Fur Regulon Leads to a Comprehensive Understanding of Iron and Fur Regulation. Int J Mol Sci 2023; 24:ijms24109078. [PMID: 37240425 DOI: 10.3390/ijms24109078] [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: 03/20/2023] [Revised: 05/16/2023] [Accepted: 05/16/2023] [Indexed: 05/28/2023] Open
Abstract
Iron is an essential element because it functions as a cofactor of many enzymes, but excess iron causes cell damage. Iron hemostasis in Escherichia coli was transcriptionally maintained by the ferric uptake regulator (Fur). Despite having been studied extensively, the comprehensive physiological roles and mechanisms of Fur-coordinated iron metabolism still remain obscure. In this work, by integrating a high-resolution transcriptomic study of the Fur wild-type and knockout Escherichia coli K-12 strains in the presence or absence of iron with high-throughput ChIP-seq assay and physiological studies, we revisited the regulatory roles of iron and Fur systematically and discovered several intriguing features of Fur regulation. The size of the Fur regulon was expanded greatly, and significant discrepancies were observed to exist between the regulations of Fur on the genes under its direct repression and activation. Fur showed stronger binding strength to the genes under its repression, and genes that were repressed by Fur were more sensitive to Fur and iron regulation as compared to the genes that were activated by Fur. Finally, we found that Fur linked iron metabolism to many essential processes, and the systemic regulations of Fur on carbon metabolism, respiration, and motility were further validated or discussed. These results highlight how Fur and Fur-controlled iron metabolism affect many cellular processes in a systematic way.
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Affiliation(s)
- Chaofan Hou
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Lin Liu
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Xian Ju
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Yunzhu Xiao
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Bingyu Li
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
| | - Conghui You
- Shenzhen Key Laboratory of Microbial Genetic Engineering, College of Life Sciences and Oceanology, Shenzhen University, Shenzhen 518055, China
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Čapek J, Večerek B. Why is manganese so valuable to bacterial pathogens? Front Cell Infect Microbiol 2023; 13:943390. [PMID: 36816586 PMCID: PMC9936198 DOI: 10.3389/fcimb.2023.943390] [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: 05/13/2022] [Accepted: 01/04/2023] [Indexed: 02/05/2023] Open
Abstract
Apart from oxygenic photosynthesis, the extent of manganese utilization in bacteria varies from species to species and also appears to depend on external conditions. This observation is in striking contrast to iron, which is similar to manganese but essential for the vast majority of bacteria. To adequately explain the role of manganese in pathogens, we first present in this review that the accumulation of molecular oxygen in the Earth's atmosphere was a key event that linked manganese utilization to iron utilization and put pressure on the use of manganese in general. We devote a large part of our contribution to explanation of how molecular oxygen interferes with iron so that it enhances oxidative stress in cells, and how bacteria have learned to control the concentration of free iron in the cytosol. The functioning of iron in the presence of molecular oxygen serves as a springboard for a fundamental understanding of why manganese is so valued by bacterial pathogens. The bulk of this review addresses how manganese can replace iron in enzymes. Redox-active enzymes must cope with the higher redox potential of manganese compared to iron. Therefore, specific manganese-dependent isoenzymes have evolved that either lower the redox potential of the bound metal or use a stronger oxidant. In contrast, redox-inactive enzymes can exchange the metal directly within the individual active site, so no isoenzymes are required. It appears that in the physiological context, only redox-inactive mononuclear or dinuclear enzymes are capable of replacing iron with manganese within the same active site. In both cases, cytosolic conditions play an important role in the selection of the metal used. In conclusion, we summarize both well-characterized and less-studied mechanisms of the tug-of-war for manganese between host and pathogen.
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Affiliation(s)
- Jan Čapek
- *Correspondence: Jan Čapek, ; Branislav Večerek,
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Rohaun SK, Imlay JA. The vulnerability of radical SAM enzymes to oxidants and soft metals. Redox Biol 2022; 57:102495. [PMID: 36240621 PMCID: PMC9576991 DOI: 10.1016/j.redox.2022.102495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 09/28/2022] [Accepted: 09/29/2022] [Indexed: 11/30/2022] Open
Abstract
Radical S-adenosylmethionine enzymes (RSEs) drive diverse biological processes by catalyzing chemically difficult reactions. Each of these enzymes uses a solvent-exposed [4Fe-4S] cluster to coordinate and cleave its SAM co-reactant. This cluster is destroyed during oxic handling, forcing investigators to work with these enzymes under anoxic conditions. Analogous substrate-binding [4Fe-4S] clusters in dehydratases are similarly sensitive to oxygen in vitro; they are also extremely vulnerable to reactive oxygen species (ROS) in vitro and in vivo. These observations suggested that ROS might similarly poison RSEs. This conjecture received apparent support by the observation that when E. coli experiences hydrogen peroxide stress, it induces a cluster-free isozyme of the RSE HemN. In the present study, surprisingly, the purified RSEs viperin and HemN proved quite resistant to peroxide and superoxide in vitro. Furthermore, pathways that require RSEs remained active inside E. coli cells that were acutely stressed by hydrogen peroxide and superoxide. Viperin, but not HemN, was gradually poisoned by molecular oxygen in vitro, forming an apparent [3Fe-4S]+ form that was readily reactivated. The modest rate of damage, and the known ability of cells to repair [3Fe-4S]+ clusters, suggest why these RSEs remain functional inside fully aerated organisms. In contrast, copper(I) damaged HemN and viperin in vitro as readily as it did fumarase, a known target of copper toxicity inside E. coli. Excess intracellular copper also impaired RSE-dependent biosynthetic processes. These data indicate that RSEs may be targets of copper stress but not of reactive oxygen species.
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Affiliation(s)
| | - James A Imlay
- Department of Microbiology, University of Illinois, Urbana, IL, 61801, USA.
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Lo HH, Chang HC, Liao CT, Hsiao YM. Expression and function of clpS and clpA in Xanthomonas campestris pv. campestris. Antonie van Leeuwenhoek 2022; 115:589-607. [PMID: 35322326 DOI: 10.1007/s10482-022-01725-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Accepted: 03/02/2022] [Indexed: 10/18/2022]
Abstract
ATP-dependent proteases (FtsH, Lon, and Clp family proteins) are ubiquitous in bacteria and play essential roles in numerous regulatory cell processes. Xanthomonas campestris pv. campestris is a Gram-negative pathogen that can cause black rot diseases in crucifers. The genome of X. campestris pv. campestris has several clp genes, namely, clpS, clpA, clpX, clpP, clpQ, and clpY. Among these genes, only clpX and clpP is known to be required for pathogenicity. Here, we focused on two uncharacterized clp genes (clpS and clpA) that encode the adaptor (ClpS) and ATPase subunit (ClpA) of the ClpAP protease complex. Transcriptional analysis revealed that the expression of clpS and clpA was growth phase-dependent and affected by the growth temperature. The inactivation of clpA, but not of clpS, resulted in susceptibility to high temperature and attenuated virulence in the host plant. The altered phenotypes of the clpA mutant could be complemented in trans. Site-directed mutagenesis revealed that K223 and K504 were the amino acid residues critical for ClpA function in heat tolerance. The protein expression profile shown by the clpA mutant in response to heat stress was different from that exhibited by the wild type. In summary, we characterized two clp genes (clpS and clpA) by examining their expression profiles and functions in different processes, including stress tolerance and pathogenicity. We demonstrated that clpS and clpA were expressed in a temperature-dependent manner and that clpA was required for the survival at high temperature and full virulence of X. campestris pv. campestris. This work represents the first time that clpS and clpA were characterized in Xanthomonas.
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Affiliation(s)
- Hsueh-Hsia Lo
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, 40601, Taiwan
| | - Hsiao-Ching Chang
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, 40601, Taiwan
| | - Chao-Tsai Liao
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, 40601, Taiwan
| | - Yi-Min Hsiao
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, 40601, Taiwan.
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Nitric oxide precipitates catastrophic chromosome fragmentation by bolstering both hydrogen peroxide and Fe(II) Fenton reactants in E. coli. J Biol Chem 2022; 298:101825. [PMID: 35288189 PMCID: PMC9018393 DOI: 10.1016/j.jbc.2022.101825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 02/23/2022] [Accepted: 03/08/2022] [Indexed: 11/22/2022] Open
Abstract
Immune cells kill invading microbes by producing reactive oxygen and nitrogen species, primarily hydrogen peroxide (H2O2) and nitric oxide (NO). We previously found that NO inhibits catalases in Escherichia coli, stabilizing H2O2 around treated cells and promoting catastrophic chromosome fragmentation via continuous Fenton reactions generating hydroxyl radicals. Indeed, H2O2-alone treatment kills catalase-deficient (katEG) mutants similar to H2O2+NO treatment. However, the Fenton reaction, in addition to H2O2, requires Fe(II), which H2O2 excess instantly converts into Fenton-inert Fe(III). For continuous Fenton when H2O2 is stable, a supply of reduced iron becomes necessary. We show here that this supply is ensured by Fe(II) recruitment from ferritins and Fe(III) reduction by flavin reductase. Our observations also concur with NO-mediated respiration inhibition that drives Fe(III) reduction. We modeled this NO-mediated inhibition via inactivation of ndh and nuo respiratory enzymes responsible for the step of NADH oxidation, which results in increased NADH pools driving flavin reduction. We found that, like the katEG mutant, the ndh nuo double mutant is similarly sensitive to H2O2-alone and H2O2+NO treatments. Moreover, the quadruple katEG ndh nuo mutant lacking both catalases and efficient respiration was rapidly killed by H2O2-alone, but this killing was delayed by NO, rather than potentiated by it. Taken together, we conclude that NO boosts the levels of both H2O2 and Fe(II) Fenton reactants, making continuous hydroxyl-radical production feasible and resulting in irreparable oxidative damage to the chromosome.
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Wu M, Shan W, Zhao GP, Lyu LD. The H2O2 Concentration-Dependent Kinetics of Gene Expression: Linking the Intensity of Oxidative Stress and Mycobacterial Physiological Adaptation. Emerg Microbes Infect 2022; 11:573-584. [PMID: 35076334 PMCID: PMC8856045 DOI: 10.1080/22221751.2022.2034484] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Defence against oxidative stress is crucial for Mycobacterium tuberculosis to survive and replicate within macrophages. Mycobacteria have evolved multilayer antioxidant systems, including scavenging enzymes, iron homeostasis, repair pathways, and metabolic adaptation, for coping with oxidative stress. How these systems are coordinated to enable the physiological adaptation to different intensities of oxidative stress, however, remains unclear. To address this, we investigated the expression kinetics of the well-characterized antioxidant genes at bacteriostatic H2O2 concentrations ranging from 1 mM to 10 mM employing Mycolicibacterium smegmatis as a model. Our results showed that most of the selected genes were expressed in a H2O2 concentration-dependent manner, whereas a subset exhibited sustained induction or repression without dose–effect, reflecting H2O2 concentration-dependent physiological adaptations. Through analyzing the dynamics of the coordinated gene expression, we demonstrated that the expressions of the H2O2 scavenging enzymes, DNA damage response, and Fe–S cluster repair function were strikingly correlated to the intensity of oxidative stress. The sustained induction of mbtB, irtA, and dnaE2 indicated that mycobacteria might deploy increased iron acquisition and error-prone lesion bypass function as fundamental strategies to counteract oxidative damages, which are distinct from the defence tactics of Escherichia coli characterized by shrinking the iron pool and delaying the DNA repair. Moreover, the distinct gene expression kinetics among the tricarboxylic acid cycle, glyoxylate shunt, and methylcitrate cycle suggested that mycobacteria could dynamically redirect its metabolic fluxes according to the intensity of oxidative stress. This work defines the H2O2 concentration-dependent gene expression kinetics and provides unique insights into mycobacterial antioxidant defence strategies.
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Affiliation(s)
- Mengying Wu
- Key Laboratory of Medical Molecular Virology of the Ministry of Education/Ministry of Health (MOE/NHC), School of Basic Medical Sciences, Fudan University, 200032 Shanghai, China
| | - Wenyan Shan
- Key Laboratory of Medical Molecular Virology of the Ministry of Education/Ministry of Health (MOE/NHC), School of Basic Medical Sciences, Fudan University, 200032 Shanghai, China
| | - Guo-Ping Zhao
- Department of Microbiology, School of Life Sciences, Fudan University, 200438 Shanghai, China
| | - Liang-Dong Lyu
- Key Laboratory of Medical Molecular Virology of the Ministry of Education/Ministry of Health (MOE/NHC), School of Basic Medical Sciences, Fudan University, 200032 Shanghai, China
- Shanghai Clinical Research Center for Infectious Disease (Tuberculosis), Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, 200433 Shanghai, China
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Gupta A, Imlay JA. Escherichia coli induces DNA repair enzymes to protect itself from low-grade hydrogen peroxide stress. Mol Microbiol 2021; 117:754-769. [PMID: 34942039 DOI: 10.1111/mmi.14870] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 12/18/2021] [Accepted: 12/18/2021] [Indexed: 11/30/2022]
Abstract
E. coli responds to hydrogen peroxide (H2 O2 ) by inducing defenses that protect H2 O2 -sensitive enzymes. DNA is believed to be another important target of oxidation, and E. coli contains enzymes that can repair oxidative lesions in vitro. However, those enzymes are not known to be induced by H2 O2 , and experiments have indicated that they are not necessary for the cell to withstand natural (low-micromolar) concentrations. In this study we used H2 O2 -scavenging mutants to impose controlled doses of H2 O2 for extended time. Transcriptomic analysis revealed that in the presence of 1 µM cytoplasmic H2 O2 , the OxyR transcription factor induced xthA, encoding exonuclease III. The xthA mutants survived a conventional 15-minute exposure to even 100 times this level of H2 O2 . However, when these mutants were exposed to 1 µM H2 O2 for hours, they accumulated DNA lesions, failed to propagate, and eventually died. Although endonuclease III (nth) was not induced, nth mutants struggled to grow. Low-grade H2 O2 stress also activated the SOS regulon, and when this induction was blocked, cell replication stopped. Collectively, these data indicate that physiological levels of H2 O2 are a real threat to DNA, and the engagement of the base-excision-repair and SOS systems is necessary to enable propagation during protracted stress.
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Affiliation(s)
- Anshika Gupta
- Department of Microbiology, University of Illinois, 601 S. Goodwin Ave, Urbana, IL, 61801, USA
| | - James A Imlay
- Department of Microbiology, University of Illinois, 601 S. Goodwin Ave, Urbana, IL, 61801, USA
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12
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Sen A, Imlay JA. How Microbes Defend Themselves From Incoming Hydrogen Peroxide. Front Immunol 2021; 12:667343. [PMID: 33995399 PMCID: PMC8115020 DOI: 10.3389/fimmu.2021.667343] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 03/19/2021] [Indexed: 12/02/2022] Open
Abstract
Microbes rely upon iron as a cofactor for many enzymes in their central metabolic processes. The reactive oxygen species (ROS) superoxide and hydrogen peroxide react rapidly with iron, and inside cells they can generate both enzyme and DNA damage. ROS are formed in some bacterial habitats by abiotic processes. The vulnerability of bacteria to ROS is also apparently exploited by ROS-generating host defense systems and bacterial competitors. Phagocyte-derived O 2 - can toxify captured bacteria by damaging unidentified biomolecules on the cell surface; it is unclear whether phagocytic H2O2, which can penetrate into the cell interior, also plays a role in suppressing bacterial invasion. Both pathogenic and free-living microbes activate defensive strategies to defend themselves against incoming H2O2. Most bacteria sense the H2O2via OxyR or PerR transcription factors, whereas yeast uses the Grx3/Yap1 system. In general these regulators induce enzymes that reduce cytoplasmic H2O2 concentrations, decrease the intracellular iron pools, and repair the H2O2-mediated damage. However, individual organisms have tailored these transcription factors and their regulons to suit their particular environmental niches. Some bacteria even contain both OxyR and PerR, raising the question as to why they need both systems. In lab experiments these regulators can also respond to nitric oxide and disulfide stress, although it is unclear whether the responses are physiologically relevant. The next step is to extend these studies to natural environments, so that we can better understand the circumstances in which these systems act. In particular, it is important to probe the role they may play in enabling host infection by microbial pathogens.
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Affiliation(s)
| | - James A. Imlay
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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