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Petrova O, Semenova E, Parfirova O, Tsers I, Gogoleva N, Gogolev Y, Nikolaichik Y, Gorshkov V. RpoS-Regulated Genes and Phenotypes in the Phytopathogenic Bacterium Pectobacterium atrosepticum. Int J Mol Sci 2023; 24:17348. [PMID: 38139177 PMCID: PMC10743746 DOI: 10.3390/ijms242417348] [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: 11/07/2023] [Revised: 12/04/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
The alternative sigma factor RpoS is considered to be one of the major regulators providing stress resistance and cross-protection in bacteria. In phytopathogenic bacteria, the effects of RpoS have not been analyzed with regard to cross-protection, and genes whose expression is directly or indirectly controlled by RpoS have not been determined at the whole-transcriptome level. Our study aimed to determine RpoS-regulated genes and phenotypes in the phytopathogenic bacterium Pectobacterium atrosepticum. Knockout of the rpoS gene in P. atrosepticum affected the long-term starvation response, cross-protection, and virulence toward plants with enhanced immune status. The whole-transcriptome profiles of the wild-type P. atrosepticum strain and its ΔrpoS mutant were compared under different experimental conditions, and functional gene groups whose expression was affected by RpoS were determined. The RpoS promoter motif was inferred within the promoter regions of the genes affected by rpoS deletion, and the P. atrosepticum RpoS regulon was predicted. Based on RpoS-controlled phenotypes, transcriptome profiles, and RpoS regulon composition, the regulatory role of RpoS in P. atrosepticum is discussed.
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Affiliation(s)
- Olga Petrova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
| | - Elizaveta Semenova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
| | - Olga Parfirova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
| | - Ivan Tsers
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
| | - Natalia Gogoleva
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
| | - Yuri Gogolev
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Yevgeny Nikolaichik
- Department of Molecular Biology, Belarusian State University, 220030 Minsk, Belarus;
| | - Vladimir Gorshkov
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
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Liao J, Li Z, Xiong D, Shen D, Wang L, Shao X, Li T, Qian G. A Novel and Efficient Platform for Discovering Noncanonical Quorum-Quenching Proteins. Microbiol Spectr 2023; 11:e0343722. [PMID: 36475880 PMCID: PMC9927378 DOI: 10.1128/spectrum.03437-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 11/11/2022] [Indexed: 12/12/2022] Open
Abstract
Quorum sensing (QS) is a well-known chemical signaling system responsible for intercellular communication that is widespread in bacteria. Acyl-homoserine lactone (AHL) is the most-studied QS signal. Previously, bacterially encoded AHL-degrading enzymes were considered to be canonical quorum-quenching proteins that have been widely used to control pathogenic infections. Here, we report a novel platform that enabled the efficient discovery of noncanonical AHL quorum-quenching proteins. This platform initially asked bacteriologists to carry out comparative genomic analyses between phylogenetically related AHL-producing and non-AHL-producing members to identify genes that are conservatively shared by non-AHL-producing members but absent in AHL-producing species. These candidate genes were then introduced into recombinant AHL-producing E. coli to screen for target proteins with the ability to block AHL production. Via this platform, we found that non-AHL-producing Lysobacter containing numerous environmentally ubiquitous members encoded a conserved glycosyltransferase-like protein Le4759, which was experimentally shown to be a noncanonical AHL-quenching protein. Le4759 could not directly degrade exogenous AHL but rather recognized and altered the activities of multiple AHL synthases through protein-protein interactions. This versatile capability enabled Le4759 to block specific AHL synthase such as CarI from Pectobacterium carotovorum to reduce its protein abundance to suppress AHL synthesis, thereby impairing bacterial infection. Thus, this study provided bacteriologists with a unique platform to discover noncanonical quorum-quenching proteins that could be developed as promising next-generation drug candidates to overcome emerging bacterial antibiotic resistance. IMPORTANCE Targeting and blocking bacterial quorum sensing (QS), the process known as quorum quenching (QQ) is an effective mean to control bacterial infection and overcome the emerging antibiotic resistance. Previously, diverse QS signal-degradation enzymes are identified as canonical QQ proteins. Here, we provided a novel and universal platform that enabled to discover previously unidentified noncanonical QQ proteins that were unable to degrade acyl-homoserine lactone (AHL) but could block AHL generation by recognizing multiple AHL synthases via direct protein-protein interactions. Our findings are believed to trigger broad interest for bacteriologists to identify potentially widely distributed noncanonical QQ proteins that have great potential for developing next-generation anti-infectious drugs.
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Affiliation(s)
- Jinxing Liao
- College of Plant Protection, Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, Jiangsu, People’s Republic of China
| | - Zihan Li
- College of Plant Protection, Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, Jiangsu, People’s Republic of China
| | - Dan Xiong
- College of Plant Protection, Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, Jiangsu, People’s Republic of China
| | - Danyu Shen
- College of Plant Protection, Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, Jiangsu, People’s Republic of China
| | - Lu Wang
- Medical College, China Three Gorges University, Yichang, People’s Republic of China
| | - Xiaolong Shao
- College of Plant Protection, Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, Jiangsu, People’s Republic of China
| | - Tao Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, People’s Republic of China
| | - Guoliang Qian
- College of Plant Protection, Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, Jiangsu, People’s Republic of China
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Zhang Y, Wang Y, Wei W, Wang M, Jia S, Yang M, Ge F. Proteomic analysis of the regulatory networks of ClpX in a model cyanobacterium Synechocystis sp. PCC 6803. FRONTIERS IN PLANT SCIENCE 2022; 13:994056. [PMID: 36247581 PMCID: PMC9560874 DOI: 10.3389/fpls.2022.994056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023]
Abstract
Protein homeostasis is tightly regulated by protein quality control systems such as chaperones and proteases. In cyanobacteria, the ClpXP proteolytic complex is regarded as a representative proteolytic system and consists of a hexameric ATPase ClpX and a tetradecameric peptidase ClpP. However, the functions and molecular mechanisms of ClpX in cyanobacteria remain unclear. This study aimed to decipher the unique contributions and regulatory networks of ClpX in the model cyanobacterium Synechocystis sp. PCC 6803 (hereafter Synechocystis). We showed that the interruption of clpX led to slower growth, decreased high light tolerance, and impaired photosynthetic cyclic electron transfer. A quantitative proteomic strategy was employed to globally identify ClpX-regulated proteins in Synechocystis cells. In total, we identified 172 differentially expressed proteins (DEPs) upon the interruption of clpX. Functional analysis revealed that these DEPs are involved in diverse biological processes, including glycolysis, nitrogen assimilation, photosynthetic electron transport, ATP-binding cassette (ABC) transporters, and two-component signal transduction. The expression of 24 DEPs was confirmed by parallel reaction monitoring (PRM) analysis. In particular, many hypothetical or unknown proteins were found to be regulated by ClpX, providing new candidates for future functional studies on ClpX. Together, our study provides a comprehensive ClpX-regulated protein network, and the results serve as an important resource for understanding protein quality control systems in cyanobacteria.
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Affiliation(s)
- Yumeng Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Yaqi Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Wei Wei
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Min Wang
- The Analysis and Testing Center, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Shuzhao Jia
- The Analysis and Testing Center, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Mingkun Yang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Feng Ge
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
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Dong S, Chen H, Zhou Q, Liao N. Protein degradation control and regulation of bacterial survival and pathogenicity: the role of protein degradation systems in bacteria. Mol Biol Rep 2021; 48:7575-7585. [PMID: 34655017 DOI: 10.1007/s11033-021-06744-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/01/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Protein degradation systems play crucial roles in all the kingdoms of life. Their natural function is to eliminate proteins that are improperly synthesized, damaged, aggregated, or short-lived, ensuring the timely and accurate regulation of the response to abrupt environmental changes. Thus, proteolysis plays an important role in protein homeostasis, quality control, and the control of regulatory processes, such as adaptation and cell development. Except for the lysosome, ATPases Associated with various cellular Activities (AAA+) ATPase-protease complex is another major protein degradation system in the cell. METHODS AND RESULTS The AAA+ ATPase-protease complex is a giant energy-dependent protease complex found in almost all kinds of cells, including bacteria, archaea and eukarya. Based on sequence analysis of ClpQ (HslV) and 20S proteasome beta subunits, it was found that bacterial ClpQ possess multiple same highly conserved motifs with 20S proteasome beta subunits of archaea and eukaryote. In this review, we also discussed the structure and functional mechanism, protein degradation signals and pathogenic role of proteasome / Clp protease complex in prokaryotes. CONCLUSION Bacterial protein degradation systems play important roles in stress tolerance, protein quality control, DNA protection, transcription and pathogenicity of bacteria. But our current knowledge of the bacterial protease system is incomplete, and further research into the Clp protease complex and associated protein degradation signals will extend our understanding of the metabolism, physiology, reproduction, and pathogenicity of bacteria.
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Affiliation(s)
- Shilei Dong
- Department of Clinical Laboratory, Zhejiang Hospital, Hangzhou, 310013, China
| | - Honghu Chen
- Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, 310051, China
| | - Qingxue Zhou
- Department of Clinical Laboratory, Hangzhou Women's Hospital (Hangzhou Maternity and Child Health Care Hospital), Hangzhou, 310008, China
| | - Ningbo Liao
- College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang, 330045, China.
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Wang H, Yang Z, Swingle B, Kvitko BH. AlgU, a Conserved Sigma Factor Regulating Abiotic Stress Tolerance and Promoting Virulence in Pseudomonas syringae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:326-336. [PMID: 33264045 DOI: 10.1094/mpmi-09-20-0254-cr] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Pseudomonas syringae can rapidly deploy specialized functions to deal with abiotic and biotic stresses. Host niches pose specific sets of environmental challenges driven, in part, by immune defenses. Bacteria use a "just-in-time" strategy of gene regulation, meaning that they only produce the functions necessary for survival as needed. Extracytoplasmic function (ECF) sigma factors transduce a specific set of environmental signals and change gene expression patterns by altering RNA polymerase promoter specificity, to adjust bacterial physiology, structure, or behavior, singly or in combination, to improve chances of survival. The broadly conserved ECF sigma factor AlgU affects virulence in both animal and plant pathogens. Pseudomonas syringae AlgU controls expression of more than 800 genes, some of which contribute to suppression of plant immunity and bacterial fitness in plants. This review discusses AlgU activation mechanisms, functions controlled by AlgU, and how these functions contribute to P. syringae survival in plants.[Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. 2021.
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Affiliation(s)
- Haibi Wang
- Department of Plant Pathology, University of Georgia, 120 Carlton St., Athens, GA 30602, U.S.A
| | - Zichu Yang
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, 334 Plant Science Bldg., Ithaca, NY 14853, U.S.A
| | - Bryan Swingle
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, 334 Plant Science Bldg., Ithaca, NY 14853, U.S.A
- Emerging Pests and Pathogens Research Unit, Robert W. Holley Center, United States Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853, U.S.A
| | - Brian H Kvitko
- Department of Plant Pathology, University of Georgia, 120 Carlton St., Athens, GA 30602, U.S.A
- The Plant Center, University of Georgia, Athens, GA 30602, U.S.A
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Yuan X, Yu M, Yang CH. Innovation and Application of the Type III Secretion System Inhibitors in Plant Pathogenic Bacteria. Microorganisms 2020; 8:microorganisms8121956. [PMID: 33317075 PMCID: PMC7764658 DOI: 10.3390/microorganisms8121956] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/05/2020] [Accepted: 12/07/2020] [Indexed: 12/16/2022] Open
Abstract
Many Gram-negative pathogenic bacteria rely on a functional type III secretion system (T3SS), which injects multiple effector proteins into eukaryotic host cells, for their pathogenicity. Genetic studies conducted in different host-microbe pathosystems often revealed a sophisticated regulatory mechanism of their T3SSs, suggesting that the expression of T3SS is tightly controlled and constantly monitored by bacteria in response to the ever-changing host environment. Therefore, it is critical to understand the regulation of T3SS in pathogenic bacteria for successful disease management. This review focuses on a model plant pathogen, Dickeyadadantii, and summarizes the current knowledge of its T3SS regulation. We highlight the roles of several T3SS regulators that were recently discovered, including the transcriptional regulators: FlhDC, RpoS, and SlyA; the post-transcriptional regulators: PNPase, Hfq with its dependent sRNA ArcZ, and the RsmA/B system; and the bacterial second messenger cyclic-di-GMP (c-di-GMP). Homologs of these regulatory components have also been characterized in almost all major bacterial plant pathogens like Erwiniaamylovora, Pseudomonassyringae, Pectobacterium spp., Xanthomonas spp., and Ralstonia spp. The second half of this review shifts focus to an in-depth discussion of the innovation and development of T3SS inhibitors, small molecules that inhibit T3SSs, in the field of plant pathology. This includes T3SS inhibitors that are derived from plant phenolic compounds, plant coumarins, and salicylidene acylhydrazides. We also discuss their modes of action in bacteria and application for controlling plant diseases.
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Affiliation(s)
- Xiaochen Yuan
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA;
| | - Manda Yu
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
- Correspondence: (M.Y.); (C.-H.Y.)
| | - Ching-Hong Yang
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
- Correspondence: (M.Y.); (C.-H.Y.)
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Li CE, Liao CT, Lo HH, Hsiao YM. Functional Characterization and Transcriptional Analysis of clpP of Xanthomonas campestris pv. campestris. Curr Microbiol 2020; 77:2876-2885. [PMID: 32623486 DOI: 10.1007/s00284-020-02093-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 06/15/2020] [Indexed: 01/24/2023]
Abstract
The caseinolytic protease (Clp) system is essential for survival under stress conditions and for virulence in several pathogenic bacteria. Xanthomonas campestris pv. campestris (Xcc) is a plant pathogen which causes black rot disease in crucifers. In this study, the Xcc clpP gene which is annotated to encode the proteolytic core of Clp was characterized. Mutation of clpP resulted in susceptibility to high temperature and puromycin stresses. Site-directed mutagenesis revealed that S105, H130, and D179 are critical amino acid residues for ClpP function in puromycin tolerance. Inactivation of clpP also revealed an attenuation of virulence on the host plant and a reduction in the production of extracellular cellulase, mannanase, pectinase, and protease. The affected phenotypes of the clpP mutant could be complemented to wild-type levels by the intact clpP gene. Transcriptional analysis revealed that expression of clpP is induced under heat shock condition.
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Affiliation(s)
- Chih-En Li
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, 406, Taiwan
| | - Chao-Tsai Liao
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, 406, Taiwan
| | - Hsueh-Hsia Lo
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, 406, Taiwan
| | - Yi-Min Hsiao
- Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Taichung, 406, Taiwan.
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The clpX gene plays an important role in bacterial attachment, stress tolerance, and virulence in Xanthomonas campestris pv. campestris. Arch Microbiol 2019; 202:597-607. [PMID: 31741013 DOI: 10.1007/s00203-019-01772-3] [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: 10/14/2019] [Revised: 10/20/2019] [Accepted: 11/07/2019] [Indexed: 01/24/2023]
Abstract
Xanthomonas campestris pv. campestris is a bacterial pathogen and the causal agent of black rot in crucifers. In this study, a clpX mutant was obtained by EZ-Tn5 transposon mutagenesis of the X. campestris pv. campestris. The clpX gene was annotated to encode ClpX, the ATP-binding subunit of ATP-dependent Clp protease. The clpX mutant exhibited reduced bacterial attachment, extracellular enzyme production and virulence. Mutation of clpX also resulted in increased sensitivity to a myriad of stresses, including heat, puromycin, and sodium dodecyl sulfate. These altered phenotypes of the clpX mutant could be restored to wild-type levels by in trans expression of the intact clpX gene. Proteomic analysis revealed that the expression of 211 proteins differed not less than twofold between the wild-type and mutant strains. Cluster of orthologous group analysis revealed that these proteins are mainly involved in metabolism, cell wall biogenesis, chaperone, and signal transduction. The reverse transcription quantitative real-time polymerase chain reaction analysis demonstrated that the expression of genes encoding attachment-related proteins, extracellular enzymes, and virulence-associated proteins was reduced after clpX mutation. The results in this study contribute to the functional understanding of the role of clpX in Xanthomonas for the first time, and extend new insights into the function of clpX in bacteria.
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Zhang B, Zhang Y, Liang F, Ma Y, Wu X. An Extract Produced by Bacillus sp. BR3 Influences the Function of the GacS/GacA Two-Component System in Pseudomonas syringae pv. tomato DC3000. Front Microbiol 2019; 10:2005. [PMID: 31572307 PMCID: PMC6749012 DOI: 10.3389/fmicb.2019.02005] [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: 04/15/2019] [Accepted: 08/15/2019] [Indexed: 12/03/2022] Open
Abstract
The GacS/GacA two-component system is essential for virulence in many plant pathogenic bacteria, and thus represents a promising anti-virulence target. In the present study, we isolated and screened rhizobacteria that were capable of inhibiting the expression of the gacS gene in the phytopathogenic bacterium Pseudomonas syringae pv. tomato (Pto) DC3000. One candidate inhibitor bacterium, BR3 was obtained and identified as a Bacillus sp. strain based on 16s rRNA gene sequence analysis. Besides the gacS gene, the GacA-dependent small RNA genes rsmZ and rsmY were repressed transcriptionally when DC3000 was treated with an extract from strain BR3. Importantly, the extract also influenced bacterial motility, the expression of type three secretion system effector AvrPto, and the plant hypersensitive response triggered by strain DC3000. The results suggested that the extract from strain BR3 might offer an alternative method to control bacterial diseases in plants by targeting the GacS/GacA system.
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Affiliation(s)
- Bo Zhang
- College of Agriculture, Guangxi University, Nanning, China
| | - Yang Zhang
- College of Agriculture, Guangxi University, Nanning, China
| | - Fei Liang
- College of Agriculture, Guangxi University, Nanning, China
| | - Yinan Ma
- Department of Plant Pathology, China Agricultural University, Beijing, China
| | - Xiaogang Wu
- College of Agriculture, Guangxi University, Nanning, China
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Figaj D, Ambroziak P, Przepiora T, Skorko-Glonek J. The Role of Proteases in the Virulence of Plant Pathogenic Bacteria. Int J Mol Sci 2019; 20:ijms20030672. [PMID: 30720762 PMCID: PMC6386880 DOI: 10.3390/ijms20030672] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/30/2019] [Accepted: 02/02/2019] [Indexed: 12/17/2022] Open
Abstract
A pathogenic lifestyle is inextricably linked with the constant necessity of facing various challenges exerted by the external environment (both within and outside the host). To successfully colonize the host and establish infection, pathogens have evolved sophisticated systems to combat the host defense mechanisms and also to be able to withstand adverse environmental conditions. Proteases, as crucial components of these systems, are involved in a variety of processes associated with infection. In phytopathogenic bacteria, they play important regulatory roles and modulate the expression and functioning of various virulence factors. Secretory proteases directly help avoid recognition by the plant immune systems, and contribute to the deactivation of the defense response pathways. Finally, proteases are important components of protein quality control systems, and thus enable maintaining homeostasis in stressed bacterial cells. In this review, we discuss the known protease functions and protease-regulated signaling processes associated with virulence of plant pathogenic bacteria.
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Affiliation(s)
- Donata Figaj
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland.
| | - Patrycja Ambroziak
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland.
| | - Tomasz Przepiora
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland.
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Wang C, Pu T, Lou W, Wang Y, Gao Z, Hu B, Fan J. Hfq, a RNA Chaperone, Contributes to Virulence by Regulating Plant Cell Wall-Degrading Enzyme Production, Type VI Secretion System Expression, Bacterial Competition, and Suppressing Host Defense Response in Pectobacterium carotovorum. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:1166-1178. [PMID: 30198820 DOI: 10.1094/mpmi-12-17-0303-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Hfq is a RNA chaperone and participates in a wide range of cellular processes and pathways. In this study, mutation of hfq gene from Pectobacterium carotovorum subsp. carotovorum PccS1 led to significantly reduced virulence and plant cell wall-degrading enzyme (PCWDE) activities. In addition, the mutant exhibited decreased biofilm formation and motility and greatly attenuated carbapenem production as well as secretion of hemolysin coregulated protein (Hcp) as compared with wild-type strain PccS1. Moreover, a higher level of callose deposition was induced in Nicotiana benthamiana leaves when infiltrated with the mutant. A total of 26 small (s)RNA deletion mutants were obtained among a predicted 27 sRNAs, and three mutants exhibited reduced virulence in the host plant. These results suggest that hfq plays a key role in Pectobacterium virulence by positively impacting PCWDE production, secretion of the type VI secretion system, bacterial competition, and suppression of host plant responses.
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Affiliation(s)
- Chunting Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Tianxin Pu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Wangying Lou
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Yujie Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Zishu Gao
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Baishi Hu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiaqin Fan
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China
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Cui Z, Yuan X, Yang CH, Huntley RB, Sun W, Wang J, Sundin GW, Zeng Q. Development of a Method to Monitor Gene Expression in Single Bacterial Cells During the Interaction With Plants and Use to Study the Expression of the Type III Secretion System in Single Cells of Dickeya dadantii in Potato. Front Microbiol 2018; 9:1429. [PMID: 30002651 PMCID: PMC6031750 DOI: 10.3389/fmicb.2018.01429] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 06/11/2018] [Indexed: 12/20/2022] Open
Abstract
Dickeya dadantii is a bacterial plant pathogen that causes soft rot disease on a wide range of host plants. The type III secretion system (T3SS) is an important virulence factor in D. dadantii. Expression of the T3SS is induced in the plant apoplast or in hrp-inducing minimal medium (hrp-MM), and is repressed in nutrient-rich media. Despite the understanding of induction conditions, how individual cells in a clonal bacterial population respond to these conditions and modulate T3SS expression is not well understood. In our previous study, we reported that in a clonal population, only a small proportion of bacteria highly expressed T3SS genes while the majority of the population did not express T3SS genes under hrp-MM condition. In this study, we developed a method that enabled in situ observation and quantification of gene expression in single bacterial cells in planta. Using this technique, we observed that the expression of the T3SS genes hrpA and hrpN is restricted to a small proportion of D. dadantii cells during the infection of potato. We also report that the expression of T3SS genes is higher at early stages of infection compared to later stages. This expression modulation is achieved through adjusting the ratio of T3SS ON and T3SS OFF cells and the expression intensity of T3SS ON cells. Our findings not only shed light into how bacteria use a bi-stable gene expression manner to modulate an important virulence factor, but also provide a useful tool to study gene expression in individual bacterial cells in planta.
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Affiliation(s)
- Zhouqi Cui
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - Xiaochen Yuan
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, United States
| | - Ching-Hong Yang
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, United States
| | - Regan B. Huntley
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - Weimin Sun
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science and Technology, Guangzhou, China
| | - Jie Wang
- Department of Plant Biology, Michigan State University, East Lansing, MI, United States
| | - George W. Sundin
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI, United States
| | - Quan Zeng
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
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13
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Wang H, Yang Z, Du S, Ma L, Liao Y, Wang Y, Toth I, Fan J. Characterization of Pectobacterium carotovorum proteins differentially expressed during infection of Zantedeschia elliotiana in vivo and in vitro which are essential for virulence. MOLECULAR PLANT PATHOLOGY 2018; 19:35-48. [PMID: 27671364 PMCID: PMC6638092 DOI: 10.1111/mpp.12493] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 09/05/2016] [Accepted: 09/19/2016] [Indexed: 05/22/2023]
Abstract
The identification of phytopathogen proteins that are differentially expressed during the course of the establishment of an infection is important to better understand the infection process. In vitro approaches, using plant extracts added to culture medium, have been used to identify such proteins, but the biological relevance of these findings for in planta infection are often uncertain until confirmed by in vivo studies. Here, we compared the proteins of Pectobacterium carotovorum ssp. carotovorum strain PccS1 differentially expressed in Luria-Bertani medium supplemented with extracts of the ornamental plant Zantedeschia elliotiana cultivar 'Black Magic' (in vitro) and in plant tissues (in vivo) by two-dimensional electrophoresis coupled with mass spectrometry. A total of 53 differentially expressed proteins (>1.5-fold) were identified (up-regulated or down-regulated in vitro, in vivo or both). Proteins that exhibited increased expression in vivo but not in vitro, or in both conditions, were identified, and deletions were made in a number of genes encoding these proteins, four of which (clpP, mreB, flgK and eda) led to a loss of virulence on Z. elliotiana, although clpP and mreB were later also shown to be reduced in growth in rich and minimal media. Although clpP, flgK and mreB have previously been reported as playing a role in virulence in plants, this is the first report of such a role for eda, which encodes 2-keto-3-deoxy-6-phosphogluconate (KDPG) aldolase, a key enzyme in Entner-Doudoroff metabolism. The results highlight the value of undertaking in vivo as well as in vitro approaches for the identification of new bacterial virulence factors.
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Affiliation(s)
- Huan Wang
- College of Plant ProtectionNanjing Agricultural UniversityNanjing210095China
| | - Zhongling Yang
- College of Plant ProtectionNanjing Agricultural UniversityNanjing210095China
| | - Shuo Du
- College of Plant ProtectionNanjing Agricultural UniversityNanjing210095China
| | - Lin Ma
- College of Plant ProtectionNanjing Agricultural UniversityNanjing210095China
| | - Yao Liao
- College of Plant ProtectionNanjing Agricultural UniversityNanjing210095China
| | - Yujie Wang
- College of Plant ProtectionNanjing Agricultural UniversityNanjing210095China
| | - Ian Toth
- Cell and Molecular SciencesJames Hutton InstituteDundeeDD2 5DAUK
| | - Jiaqin Fan
- College of Plant ProtectionNanjing Agricultural UniversityNanjing210095China
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14
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Lee JH, Zhao Y. ClpXP-Dependent RpoS Degradation Enables Full Activation of Type III Secretion System, Amylovoran Production, and Motility in Erwinia amylovora. PHYTOPATHOLOGY 2017; 107:1346-1352. [PMID: 28691868 DOI: 10.1094/phyto-06-17-0198-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Erwinia amylovora, the causal agent of fire blight disease of apple and pear, employs intracellular proteases, including Lon and ClpXP, for posttranslational regulation of various cellular proteins. It has been shown that Lon plays a critical role in E. amylovora virulence by directly targeting type III secretion system (T3SS) proteins and the Rcs phosphorelay system. In this study, we genetically examined the role of ClpXP and its potential interaction with Lon in E. amylovora. Mutation in clpXP diminished the expression of the T3SS, reduced exopolysaccharide amylovoran production and motility, and resulted in delayed disease progress. Western blot analyses showed highly accumulated RpoS proteins in the clpXP mutant. Moreover, mutation of rpoS in the clpXP mutant background rescued the expression of the T3SS and amylovoran production, suggesting that ClpXP-dependent RpoS degradation positively affects virulence traits. Interestingly, lack of both ClpXP and Lon resulted in significantly reduced virulence but increased expression of the T3SS and amylovoran production. However, this phenomenon was independent of RpoS accumulation, suggesting that ClpXP and Lon are indispensable for full virulence in E. amylovora.
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Affiliation(s)
- Jae Hoon Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana 61801
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana 61801
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15
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Jiang H, Jiang M, Yang L, Yao P, Ma L, Wang C, Wang H, Qian G, Hu B, Fan J. The Ribosomal Protein RplY Is Required for Pectobacterium carotovorum Virulence and Is Induced by Zantedeschia elliotiana Extract. PHYTOPATHOLOGY 2017; 107:1322-1330. [PMID: 28853642 DOI: 10.1094/phyto-04-17-0161-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Pectobacterium carotovorum subsp. carotovorum strain PccS1, a bacterial pathogen causing soft rot disease of Zantedeschia elliotiana (colored calla), was investigated for virulence genes induced by the host plant. Using a promoter-trap transposon (mariner), we obtained 500 transposon mutants showing kanamycin resistance dependent on extract of Z. elliotiana. One of these mutants, PM86, exhibited attenuated virulence on both Z. elliotiana and Brassica rapa subsp. pekinensis. The growth of PM86 was also reduced in minimal medium (MM), and the reduction was restored by adding plant extract to the MM. The gene containing the insertion site was identified as rplY. The deletion mutant ΔrplY, exhibited reduced virulence, motility and plant cell wall-degrading enzyme production but not biofilm formation. Analysis of gene expression and reporter fusions revealed that the rplY gene in PccS1 is up-regulated at both the transcriptional and the translational levels in the presence of plant extract. Our results suggest that rplY is induced by Z. elliotiana extract and is crucial for virulence in P. carotovorum subsp. carotovorum.
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Affiliation(s)
- Huan Jiang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Mengyi Jiang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Liuke Yang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Peiyan Yao
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Lin Ma
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Chunting Wang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Huan Wang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Gouliang Qian
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Baishi Hu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jiaqin Fan
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China
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16
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Li Y, Hutchins W, Wu X, Liang C, Zhang C, Yuan X, Khokhani D, Chen X, Che Y, Wang Q, Yang CH. Derivative of plant phenolic compound inhibits the type III secretion system of Dickeya dadantii via HrpX/HrpY two-component signal transduction and Rsm systems. MOLECULAR PLANT PATHOLOGY 2015; 16:150-63. [PMID: 24986378 PMCID: PMC6638520 DOI: 10.1111/mpp.12168] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The type III secretion system (T3SS) is a major virulence factor in many Gram-negative bacterial pathogens and represents a particularly appealing target for antimicrobial agents. Previous studies have shown that the plant phenolic compound p-coumaric acid (PCA) plays a role in the inhibition of T3SS expression of the phytopathogen Dickeya dadantii 3937. This study screened a series of derivatives of plant phenolic compounds and identified that trans-4-hydroxycinnamohydroxamic acid (TS103) has an eight-fold higher inhibitory potency than PCA on the T3SS of D. dadantii. The effect of TS103 on regulatory components of the T3SS was further elucidated. Our results suggest that TS103 inhibits HrpY phosphorylation and leads to reduced levels of hrpS and hrpL transcripts. In addition, through a reduction in the RNA levels of the regulatory small RNA RsmB, TS103 also inhibits hrpL at the post-transcriptional level via the rsmB-RsmA regulatory pathway. Finally, TS103 inhibits hrpL transcription and mRNA stability, which leads to reduced expression of HrpL regulon genes, such as hrpA and hrpN. To our knowledge, this is the first inhibitor to affect the T3SS through both the transcriptional and post-transcriptional pathways in the soft-rot phytopathogen D. dadantii 3937.
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Affiliation(s)
- Yan Li
- The MOA Key Laboratory of Plant Pathology, Department of Plant Pathology, College of Agronomy & Biotechnology, China Agricultural University, Beijing, 100193, China
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Schmitz KR, Carney DW, Sello JK, Sauer RT. Crystal structure of Mycobacterium tuberculosis ClpP1P2 suggests a model for peptidase activation by AAA+ partner binding and substrate delivery. Proc Natl Acad Sci U S A 2014; 111:E4587-95. [PMID: 25267638 PMCID: PMC4217457 DOI: 10.1073/pnas.1417120111] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Caseinolytic peptidase P (ClpP), a double-ring peptidase with 14 subunits, collaborates with ATPases associated with diverse activities (AAA+) partners to execute ATP-dependent protein degradation. Although many ClpP enzymes self-assemble into catalytically active homo-tetradecamers able to cleave small peptides, the Mycobacterium tuberculosis enzyme consists of discrete ClpP1 and ClpP2 heptamers that require a AAA+ partner and protein-substrate delivery or a peptide agonist to stabilize assembly of the active tetradecamer. Here, we show that cyclic acyldepsipeptides (ADEPs) and agonist peptides synergistically activate ClpP1P2 by mimicking AAA+ partners and substrates, respectively, and determine the structure of the activated complex. Our studies establish the basis of heteromeric ClpP1P2 assembly and function, reveal tight coupling between the conformations of each ring, show that ADEPs bind only to one ring but appear to open the axial pores of both rings, provide a foundation for rational drug development, and suggest strategies for studying the roles of individual ClpP1 and ClpP2 rings in Clp-family proteolysis.
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Affiliation(s)
- Karl R Schmitz
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139; and
| | - Daniel W Carney
- Department of Chemistry, Brown University, Providence, RI 02912
| | - Jason K Sello
- Department of Chemistry, Brown University, Providence, RI 02912
| | - Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139; and
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Wu X, Zeng Q, Koestler BJ, Waters CM, Sundin GW, Hutchins W, Yang CH. Deciphering the components that coordinately regulate virulence factors of the soft rot pathogen Dickeya dadantii. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:1119-1131. [PMID: 25180688 DOI: 10.1094/mpmi-01-14-0026-r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The bacterial soft rot pathogen Dickeya dadantii utilizes the type III secretion system (T3SS) to suppress host defense responses, and secretes pectate lyase (Pel) to disintegrate the plant cell wall. A transposon mutagenesis fluorescence-activated cell sorting screen was used to identify mutants with altered promoter activities of the T3SS pilus gene hrpA. Several insertion mutations, resulting in changes in hrpA expression, were mapped to a new locus, opgGH, which encodes the gene cluster responsible for osmoregulated periplasmic glucan (OPG) synthesis proteins. Our data showed that OPG was involved in T3SS and Pel regulation by altering the expression of the regulatory small RNA RsmB. Through genome searching, the mechanism of two novel regulatory components, the RcsCD-RcsB phosphorelay and CsrD on OPG and the rsmB gene, was further investigated. The Rcs phosphorelay and OPG inversely regulated rsmB at transcriptional and post-transcriptional levels, respectively. CsrD exhibited dual functionality in T3SS and Pel regulation by manipulating levels of RsmB RNA and cyclic diguanylate monophosphate (c-di-GMP). CsrD positively regulated the promoter activity of the rsmB gene but negatively controlled RsmB RNA at the post-transcriptional level via OpgGH. In addition, CsrD contains both GGDEF and EAL domains but acted as a c-di-GMP phosphodiesterase. When the expression of the csrD gene was induced, CsrD regulated T3SS expression and Pel production through controlling intracellular c-di-GMP levels.
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Genome Sequence of Dickeya solani, a New soft Rot Pathogen of Potato, Suggests its Emergence May Be Related to a Novel Combination of Non-Ribosomal Peptide/Polyketide Synthetase Clusters. DIVERSITY-BASEL 2013. [DOI: 10.3390/d5040824] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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ClpP deletion causes attenuation of Salmonella Typhimurium virulence through mis-regulation of RpoS and indirect control of CsrA and the SPI genes. Microbiology (Reading) 2013; 159:1497-1509. [DOI: 10.1099/mic.0.065797-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Yamazaki A, Li J, Hutchins WC, Wang L, Ma J, Ibekwe AM, Yang CH. Commensal effect of pectate lyases secreted from Dickeya dadantii on proliferation of Escherichia coli O157:H7 EDL933 on lettuce leaves. Appl Environ Microbiol 2011; 77:156-62. [PMID: 21075884 PMCID: PMC3019694 DOI: 10.1128/aem.01079-10] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 10/31/2010] [Indexed: 11/20/2022] Open
Abstract
The outbreaks caused by enterohemorrhagic Escherichia coli O157:H7 on leafy greens have raised serious and immediate food safety concerns. It has been suggested that several phytopathogens aid in the persistence and proliferation of the human enteropathogens in the phyllosphere. In this work, we examined the influence of virulence mechanisms of Dickeya dadantii 3937, a broad-host-range phytopathogen, on the proliferation of the human pathogen E. coli O157:H7 EDL933 (EDL933) on postharvest lettuce by coinoculation of EDL933 with D. dadantii 3937 derivatives that have mutations in virulence-related genes. A type II secretion system (T2SS)-deficient mutant of D. dadantii 3937, A1919 (ΔoutC), lost the capability to promote the multiplication of EDL933, whereas Ech159 (ΔrpoS), a stress-responsive σ factor RpoS-deficient mutant, increased EDL933 proliferation on lettuce leaves. A spectrophotometric enzyme activity assay revealed that A1919 (ΔoutC) was completely deficient in the secretion of pectate lyases (Pels), which play a major role in plant tissue maceration. In contrast to A1919 (ΔoutC), Ech159 (ΔrpoS) showed more than 2-fold-greater Pel activity than the wild-type D. dadantii 3937. Increased expression of pelD (encodes an endo-pectate lyase) was observed in Ech159 (ΔrpoS) in planta. These results suggest that the pectinolytic activity of D. dadantii 3937 is the dominant determinant of enhanced EDL933 proliferation on the lettuce leaves. In addition, RpoS, the general stress response σ factor involved in cell survival in suboptimal conditions, plays a role in EDL933 proliferation by controlling the production of pectate lyases in D. dadantii 3937.
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Affiliation(s)
- Akihiro Yamazaki
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - Jin Li
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - William C. Hutchins
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - Lixia Wang
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - Jincai Ma
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - A. Mark Ibekwe
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - Ching-Hong Yang
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
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