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Yin R, Cheng J, Lin J. The role of the type VI secretion system in the stress resistance of plant-associated bacteria. STRESS BIOLOGY 2024; 4:16. [PMID: 38376647 PMCID: PMC10879055 DOI: 10.1007/s44154-024-00151-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 01/26/2024] [Indexed: 02/21/2024]
Abstract
The type VI secretion system (T6SS) is a powerful bacterial molecular weapon that can inject effector proteins into prokaryotic or eukaryotic cells, thereby participating in the competition between bacteria and improving bacterial environmental adaptability. Although most current studies of the T6SS have focused on animal bacteria, this system is also significant for the adaptation of plant-associated bacteria. This paper briefly introduces the structure and biological functions of the T6SS. We summarize the role of plant-associated bacterial T6SS in adaptability to host plants and the external environment, including resistance to biotic stresses such as host defenses and competition from other bacteria. We review the role of the T6SS in response to abiotic factors such as acid stress, oxidation stress, and osmotic stress. This review provides an important reference for exploring the functions of the T6SS in plant-associated bacteria. In addition, characterizing these anti-stress functions of the T6SS may provide new pathways toward eliminating plant pathogens and controlling agricultural losses.
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Affiliation(s)
- Rui Yin
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, 716000, Shaanxi, China
| | - Juanli Cheng
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, 716000, Shaanxi, China
| | - Jinshui Lin
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, 716000, Shaanxi, China.
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2
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Chai G, Li J, Li Z. The interactive effects of ocean acidification and warming on bioeroding sponge Spheciospongia vesparium microbiome indicated by metatranscriptomics. Microbiol Res 2024; 278:127542. [PMID: 37979302 DOI: 10.1016/j.micres.2023.127542] [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: 08/03/2023] [Revised: 10/30/2023] [Accepted: 11/01/2023] [Indexed: 11/20/2023]
Abstract
Global climate change will cause coral reefs decline and is expected to increase the reef erosion potential of bioeroding sponges. Microbial symbionts are essential for the overall fitness and survival of sponge holobionts in changing ocean environments. However, we rarely know about the impacts of ocean warming and acidification on bioeroding sponge microbiome. Here, the structural and functional changes of the bioeroding sponge Spheciospongia vesparium microbiome, as well as its recovery potential, were investigated at the RNA level in a laboratory system simulating 32 °C and pH 7.7. Based on metatranscriptome analysis, acidification showed no significant impact, while warming or simultaneous warming and acidification disrupted the sponge microbiome. Warming caused microbial dysbiosis and recruited potentially opportunistic and pathogenic members of Nesiotobacter, Oceanospirillaceae, Deltaproteobacteria, Epsilonproteobacteria, Bacteroidetes and Firmicutes. Moreover, warming disrupted nutrient exchange and molecular interactions in the sponge holobiont, accompanied by stimulation of virulence activity and anaerobic metabolism including denitrification and dissimilatory reduction of nitrate and sulfate to promote sponge necrosis. Particularly, the interaction between acidification and warming alleviated the negative effects of warming and enhanced the Rhodobacteraceae-driven ethylmalonyl-CoA pathway and sulfur-oxidizing multienzyme system. The microbiome could not recover during the experiment period after warming or combined stress was removed. This study suggests that warming or combined warming and acidification will irreversibly destabilize the S. vesparium microbial community structure and function, and provides insight into the molecular mechanisms of the interactive effects of acidification and warming on the sponge microbiome.
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Affiliation(s)
- Guangjun Chai
- Marine Biotechnology Laboratory, State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jinlong Li
- Marine Biotechnology Laboratory, State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhiyong Li
- Marine Biotechnology Laboratory, State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
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3
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Schmidt JJ, Remme DCLE, Eisfeld J, Brandenburg VB, Bille H, Narberhaus F. The LysR-type transcription factor LsrB regulates beta-lactam resistance in Agrobacterium tumefaciens. Mol Microbiol 2024; 121:26-39. [PMID: 37985428 DOI: 10.1111/mmi.15191] [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: 08/09/2023] [Revised: 10/20/2023] [Accepted: 10/28/2023] [Indexed: 11/22/2023]
Abstract
Agrobacterium tumefaciens is a plant pathogen, broadly known as the causal agent of the crown gall disease. The soil bacterium is naturally resistant to beta-lactam antibiotics by utilizing the inducible beta-lactamase AmpC. Our picture on the condition-dependent regulation of ampC expression is incomplete. A known regulator is AmpR controlling the transcription of ampC in response to unrecycled muropeptides as a signal for cell wall stress. In our study, we uncovered the global transcriptional regulator LsrB as a critical player acting upstream of AmpR. Deletion of lsrB led to severe ampicillin and penicillin sensitivity, which could be restored to wild-type levels by lsrB complementation. By transcriptome profiling via RNA-Seq and qRT-PCR and by electrophoretic mobility shift assays, we show that ampD coding for an anhydroamidase involved in peptidoglycan recycling is under direct negative control by LsrB. Controlling AmpD levels by the LysR-type regulator in turn impacts the cytoplasmic concentration of cell wall degradation products and thereby the AmpR-mediated regulation of ampC. Our results substantially expand the existing model of inducible beta-lactam resistance in A. tumefaciens by establishing LsrB as higher-level transcriptional regulator.
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Affiliation(s)
| | | | - Jessica Eisfeld
- Medical Microbiology, Ruhr University Bochum, Bochum, Germany
| | | | - Hannah Bille
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
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4
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Bustamante JA, Ceron JS, Gao IT, Ramirez HA, Aviles MV, Bet Adam D, Brice JR, Cuellar RA, Dockery E, Jabagat MK, Karp DG, Lau JKO, Li S, Lopez-Magaña R, Moore RR, Morin BKR, Nzongo J, Rezaeihaghighi Y, Sapienza-Martinez J, Tran TTK, Huang Z, Duthoy AJ, Barnett MJ, Long SR, Chen JC. A protease and a lipoprotein jointly modulate the conserved ExoR-ExoS-ChvI signaling pathway critical in Sinorhizobium meliloti for symbiosis with legume hosts. PLoS Genet 2023; 19:e1010776. [PMID: 37871041 PMCID: PMC10659215 DOI: 10.1371/journal.pgen.1010776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 11/20/2023] [Accepted: 10/11/2023] [Indexed: 10/25/2023] Open
Abstract
Sinorhizobium meliloti is a model alpha-proteobacterium for investigating microbe-host interactions, in particular nitrogen-fixing rhizobium-legume symbioses. Successful infection requires complex coordination between compatible host and endosymbiont, including bacterial production of succinoglycan, also known as exopolysaccharide-I (EPS-I). In S. meliloti EPS-I production is controlled by the conserved ExoS-ChvI two-component system. Periplasmic ExoR associates with the ExoS histidine kinase and negatively regulates ChvI-dependent expression of exo genes, necessary for EPS-I synthesis. We show that two extracytoplasmic proteins, LppA (a lipoprotein) and JspA (a lipoprotein and a metalloprotease), jointly influence EPS-I synthesis by modulating the ExoR-ExoS-ChvI pathway and expression of genes in the ChvI regulon. Deletions of jspA and lppA led to lower EPS-I production and competitive disadvantage during host colonization, for both S. meliloti with Medicago sativa and S. medicae with M. truncatula. Overexpression of jspA reduced steady-state levels of ExoR, suggesting that the JspA protease participates in ExoR degradation. This reduction in ExoR levels is dependent on LppA and can be replicated with ExoR, JspA, and LppA expressed exogenously in Caulobacter crescentus and Escherichia coli. Akin to signaling pathways that sense extracytoplasmic stress in other bacteria, JspA and LppA may monitor periplasmic conditions during interaction with the plant host to adjust accordingly expression of genes that contribute to efficient symbiosis. The molecular mechanisms underlying host colonization in our model system may have parallels in related alpha-proteobacteria.
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Affiliation(s)
- Julian A. Bustamante
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Josue S. Ceron
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Ivan Thomas Gao
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Hector A. Ramirez
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Milo V. Aviles
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Demsin Bet Adam
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Jason R. Brice
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Rodrigo A. Cuellar
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Eva Dockery
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Miguel Karlo Jabagat
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Donna Grace Karp
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Joseph Kin-On Lau
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Suling Li
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Raymondo Lopez-Magaña
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Rebecca R. Moore
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Bethany Kristi R. Morin
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Juliana Nzongo
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Yasha Rezaeihaghighi
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Joseph Sapienza-Martinez
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Tuyet Thi Kim Tran
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Zhenzhong Huang
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Aaron J. Duthoy
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Melanie J. Barnett
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Sharon R. Long
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Joseph C. Chen
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
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Greenwich JL, Heckel BC, Alakavuklar MA, Fuqua C. The ChvG-ChvI Regulatory Network: A Conserved Global Regulatory Circuit Among the Alphaproteobacteria with Pervasive Impacts on Host Interactions and Diverse Cellular Processes. Annu Rev Microbiol 2023; 77:131-148. [PMID: 37040790 DOI: 10.1146/annurev-micro-120822-102714] [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] [Indexed: 04/13/2023]
Abstract
The ChvG-ChvI two-component system is conserved among multiple Alphaproteobacteria. ChvG is a canonical two-component system sensor kinase with a single large periplasmic loop. Active ChvG directs phosphotransfer to its cognate response regulator ChvI, which controls transcription of target genes. In many alphaproteobacteria, ChvG is regulated by a third component, a periplasmic protein called ExoR, that maintains ChvG in an inactive state through direct interaction. Acidic pH stimulates proteolysis of ExoR, unfettering ChvG-ChvI to control its regulatory targets. Activated ChvI among different alphaproteobacteria controls a broad range of cellular processes, including symbiosis and virulence, exopolysaccharide production, biofilm formation, motility, type VI secretion, cellular metabolism, envelope composition, and growth. Low pH is a virulence signal in Agrobacterium tumefaciens, but in other systems, conditions that cause envelope stress may also generally activate ChvG-ChvI. There is mounting evidence that these regulators influence diverse aspects of bacterial physiology, including but not limited to host interactions.
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Affiliation(s)
| | - Brynn C Heckel
- Department of Biology, Indiana University, Bloomington, Indiana, USA; ,
- Current affiliation: California State University, Dominguez Hills, California, USA;
| | - Melene A Alakavuklar
- Department of Biology, Indiana University, Bloomington, Indiana, USA; ,
- Current affiliation: Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA;
| | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, Indiana, USA; ,
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Weisberg AJ, Wu Y, Chang JH, Lai EM, Kuo CH. Virulence and Ecology of Agrobacteria in the Context of Evolutionary Genomics. ANNUAL REVIEW OF PHYTOPATHOLOGY 2023; 61:1-23. [PMID: 37164023 DOI: 10.1146/annurev-phyto-021622-125009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Among plant-associated bacteria, agrobacteria occupy a special place. These bacteria are feared in the field as agricultural pathogens. They cause abnormal growth deformations and significant economic damage to a broad range of plant species. However, these bacteria are revered in the laboratory as models and tools. They are studied to discover and understand basic biological phenomena and used in fundamental plant research and biotechnology. Agrobacterial pathogenicity and capability for transformation are one and the same and rely on functions encoded largely on their oncogenic plasmids. Here, we synthesize a substantial body of elegant work that elucidated agrobacterial virulence mechanisms and described their ecology. We review findings in the context of the natural diversity that has been recently unveiled for agrobacteria and emphasize their genomics and plasmids. We also identify areas of research that can capitalize on recent findings to further transform our understanding of agrobacterial virulence and ecology.
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Affiliation(s)
- Alexandra J Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA;
| | - Yu Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan;
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA;
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan;
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, Taiwan
- Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan;
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung Hsing University and Academia Sinica, Taipei, Taiwan
- Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
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7
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Rivas-Solano O, Núñez-Montero K, Altamirano-Silva P, Ruiz-Villalobos N, Barquero-Calvo E, Moreno E, Chaves-Olarte E, Guzmán-Verri C. A bvrR/bvrS Non-Polar Brucella abortus Mutant Confirms the Role of the Two-Component System BvrR/BvrS in Virulence and Membrane Integrity. Microorganisms 2023; 11:2014. [PMID: 37630574 PMCID: PMC10459465 DOI: 10.3390/microorganisms11082014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/25/2023] [Accepted: 08/02/2023] [Indexed: 08/27/2023] Open
Abstract
Brucella abortus is a bacterial pathogen causing bovine brucellosis worldwide. This facultative extracellular-intracellular pathogen can be transmitted to humans, leading to a zoonotic disease. The disease remains a public health concern, particularly in regions where livestock farming is present. The two-component regulatory system BvrR/BvrS was described by isolating the attenuated transposition mutants bvrR::Tn5 and bvrS::Tn5, whose characterization led to the understanding of the role of the system in bacterial survival. However, a phenotypic comparison with deletion mutants has not been performed because their construction has been unsuccessful in brucellae and difficult in phylogenetically related Rhizobiales with BvrR/BvrS orthologs. Here, we used an unmarked gene excision strategy to generate a B. abortus mutant strain lacking both genes, called B. abortus ∆bvrRS. The deletion was verified through PCR, Southern blot, Western blot, Sanger sequencing, and whole-genome sequencing, confirming a clean mutation without further alterations at the genome level. B. abortus ∆bvrRS shared attenuated phenotypic traits with both transposition mutants, confirming the role of BvrR/BvrS in pathogenesis and membrane integrity. This B. abortus ∆bvrRS with a non-antimicrobial marker is an excellent tool for continuing studies on the role of BvrR/BvrS in the B. abortus lifestyle.
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Affiliation(s)
- Olga Rivas-Solano
- Centro de Investigación en Biotecnología, Instituto Tecnológico de Costa Rica, Cartago 30109, Costa Rica
| | - Kattia Núñez-Montero
- Laboratorio Facultad Ciencias de la Salud, Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Temuco 4813003, Chile;
| | - Pamela Altamirano-Silva
- Centro de Investigación en Enfermedades Tropicales, Universidad de Costa Rica, San Pedro de Montes de Oca, San José 2060, Costa Rica; (P.A.-S.); (E.C.-O.)
| | - Nazareth Ruiz-Villalobos
- Programa de Investigación en Enfermedades Tropicales, Universidad Nacional, Heredia 40104, Costa Rica; (N.R.-V.); (E.B.-C.); (E.M.); (C.G.-V.)
| | - Elías Barquero-Calvo
- Programa de Investigación en Enfermedades Tropicales, Universidad Nacional, Heredia 40104, Costa Rica; (N.R.-V.); (E.B.-C.); (E.M.); (C.G.-V.)
| | - Edgardo Moreno
- Programa de Investigación en Enfermedades Tropicales, Universidad Nacional, Heredia 40104, Costa Rica; (N.R.-V.); (E.B.-C.); (E.M.); (C.G.-V.)
| | - Esteban Chaves-Olarte
- Centro de Investigación en Enfermedades Tropicales, Universidad de Costa Rica, San Pedro de Montes de Oca, San José 2060, Costa Rica; (P.A.-S.); (E.C.-O.)
| | - Caterina Guzmán-Verri
- Programa de Investigación en Enfermedades Tropicales, Universidad Nacional, Heredia 40104, Costa Rica; (N.R.-V.); (E.B.-C.); (E.M.); (C.G.-V.)
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8
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Hespanhol JT, Nóbrega-Silva L, Bayer-Santos E. Regulation of type VI secretion systems at the transcriptional, posttranscriptional and posttranslational level. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001376. [PMID: 37552221 PMCID: PMC10482370 DOI: 10.1099/mic.0.001376] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/25/2023] [Indexed: 08/09/2023]
Abstract
Bacteria live in complex polymicrobial communities and are constantly competing for resources. The type VI secretion system (T6SS) is a widespread antagonistic mechanism used by Gram-negative bacteria to gain an advantage over competitors. T6SSs translocate toxic effector proteins inside target prokaryotic cells in a contact-dependent manner. In addition, some T6SS effectors can be secreted extracellularly and contribute to the scavenging scarce metal ions. Bacteria deploy their T6SSs in different situations, categorizing these systems into offensive, defensive and exploitative. The great variety of bacterial species and environments occupied by such species reflect the complexity of regulatory signals and networks that control the expression and activation of the T6SSs. Such regulation is tightly controlled at the transcriptional, posttranscriptional and posttranslational level by abiotic (e.g. pH, iron) or biotic (e.g. quorum-sensing) cues. In this review, we provide an update on the current knowledge about the regulatory networks that modulate the expression and activity of T6SSs across several species, focusing on systems used for interbacterial competition.
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Affiliation(s)
- Julia Takuno Hespanhol
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | - Luize Nóbrega-Silva
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
| | - Ethel Bayer-Santos
- Department of Microbiology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo 05508-900, Brazil
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Liu H, Wei Z, Li J, Liu X, Zhu L, Wang Y, Wang T, Li C, Shen X. A Yersinia T6SS Effector YezP Engages the Hemin Uptake Receptor HmuR and ZnuABC for Zn 2+ Acquisition. Appl Environ Microbiol 2023; 89:e0024023. [PMID: 37338394 PMCID: PMC10370319 DOI: 10.1128/aem.00240-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 05/25/2023] [Indexed: 06/21/2023] Open
Abstract
Metal ions are essential nutrients for all life forms, and restriction of metal ion availability is an effective host defense against bacterial infection. Meanwhile, bacterial pathogens have developed equally effective means to secure their metal ion supply. The enteric pathogen Yersinia pseudotuberculosis was found to uptake zinc using the T6SS4 effector YezP, which is essential for Zn2+ acquisition and bacterial survival under oxidative stress. However, the mechanism of this zinc uptake pathway has not been fully elucidated. Here, we identified the hemin uptake receptor HmuR for YezP, which can mediate import of Zn2+ into the periplasm by the YezP-Zn2+ complex and demonstrated that YezP functions extracellularly. This study also confirmed that the ZnuCB transporter is the inner membrane transporter for Zn2+ from the periplasm to cytoplasm. Overall, our results reveal the complete T6SS/YezP/HmuR/ZnuABC pathway, wherein multiple systems are coupled to support zinc uptake by Y. pseudotuberculosis under oxidative stress. IMPORTANCE Identifying the transporters involved in import of metal ions under normal physiological growth conditions in bacterial pathogens will clarify its pathogenic mechanism. Y. pseudotuberculosis YPIII, a common foodborne pathogen that infects animals and humans, uptake zinc via the T6SS4 effector YezP. However, the outer and inner transports involved in Zn2+ acquisition remain unknown. The important outcomes of this study are the identification of the hemin uptake receptor HmuR and inner membrane transporter ZnuCB that import Zn2+ into the cytoplasm via the YezP-Zn2+ complex, and elucidation of the complete Zn2+ acquisition pathway consisting of T6SS, HmuRSTUV, and ZnuABC, thereby providing a comprehensive view of T6SS-mediated ion transport and its functions.
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Affiliation(s)
- Hai Liu
- Qingyang Longfeng Sponge City Construction Management & Operation Co., Ltd, Qingyang, Gansu, China
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Zhiyan Wei
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Jiali Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Xingyu Liu
- State Key Laboratory of Geological Processes and Mineral Resources, Institute of Earth Sciences, China University of Geosciences, Beijing, China
| | - Lingfang Zhu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Yao Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Tietao Wang
- Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Sciences, Northwest University, Xi'an, Shaanxi, China
| | - Changfu Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
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10
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Brown PJB, Chang JH, Fuqua C. Agrobacterium tumefaciens: a Transformative Agent for Fundamental Insights into Host-Microbe Interactions, Genome Biology, Chemical Signaling, and Cell Biology. J Bacteriol 2023; 205:e0000523. [PMID: 36892285 PMCID: PMC10127608 DOI: 10.1128/jb.00005-23] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/10/2023] Open
Abstract
Agrobacterium tumefaciens incites the formation of readily visible macroscopic structures known as crown galls on plant tissues that it infects. Records from biologists as early as the 17th century noted these unusual plant growths and began examining the basis for their formation. These studies eventually led to isolation of the infectious agent, A. tumefaciens, and decades of study revealed the remarkable mechanisms by which A. tumefaciens causes crown gall through stable horizontal genetic transfer to plants. This fundamental discovery generated a barrage of applications in the genetic manipulation of plants that is still under way. As a consequence of the intense study of A. tumefaciens and its role in plant disease, this pathogen was developed as a model for the study of critical processes that are shared by many bacteria, including host perception during pathogenesis, DNA transfer and toxin secretion, bacterial cell-cell communication, plasmid biology, and more recently, asymmetric cell biology and composite genome coordination and evolution. As such, studies of A. tumefaciens have had an outsized impact on diverse areas within microbiology and plant biology that extend far beyond its remarkable agricultural applications. In this review, we attempt to highlight the colorful history of A. tumefaciens as a study system, as well as current areas that are actively demonstrating its value and utility as a model microorganism.
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Affiliation(s)
- Pamela J. B. Brown
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, USA
| | - Jeff H. Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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11
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Calvopina-Chavez DG, Howarth RE, Memmott AK, Pech Gonzalez OH, Hafen CB, Jensen KT, Benedict AB, Altman JD, Burnside BS, Childs JS, Dallon SW, DeMarco AC, Flindt KC, Grover SA, Heninger E, Iverson CS, Johnson AK, Lopez JB, Meinzer MA, Moulder BA, Moulton RI, Russell HS, Scott TM, Shiobara Y, Taylor MD, Tippets KE, Vainerere KM, Von Wallwitz IC, Wagley M, Wiley MS, Young NJ, Griffitts JS. A large-scale genetic screen identifies genes essential for motility in Agrobacterium fabrum. PLoS One 2023; 18:e0279936. [PMID: 36598925 PMCID: PMC9812332 DOI: 10.1371/journal.pone.0279936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 12/17/2022] [Indexed: 01/05/2023] Open
Abstract
The genetic and molecular basis of flagellar motility has been investigated for several decades, with innovative research strategies propelling advances at a steady pace. Furthermore, as the phenomenon is examined in diverse bacteria, new taxon-specific regulatory and structural features are being elucidated. Motility is also a straightforward bacterial phenotype that can allow undergraduate researchers to explore the palette of molecular genetic tools available to microbiologists. This study, driven primarily by undergraduate researchers, evaluated hundreds of flagellar motility mutants in the Gram-negative plant-associated bacterium Agrobacterium fabrum. The nearly saturating screen implicates a total of 37 genes in flagellar biosynthesis, including genes of previously unknown function.
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Affiliation(s)
- Diana G. Calvopina-Chavez
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Robyn E. Howarth
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Audrey K. Memmott
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Oscar H. Pech Gonzalez
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Caleb B. Hafen
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kyson T. Jensen
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Alex B. Benedict
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Jessica D. Altman
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Brittany S. Burnside
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Justin S. Childs
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Samuel W. Dallon
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Alexa C. DeMarco
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kirsten C. Flindt
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Sarah A. Grover
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Elizabeth Heninger
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Christina S. Iverson
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Abigail K. Johnson
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Jack B. Lopez
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - McKay A. Meinzer
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Brook A. Moulder
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Rebecca I. Moulton
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Hyrum S. Russell
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Tiana M. Scott
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Yuka Shiobara
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Mason D. Taylor
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kathryn E. Tippets
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kayla M. Vainerere
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Isabella C. Von Wallwitz
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Madison Wagley
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Megumi S. Wiley
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Naomi J. Young
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Joel S. Griffitts
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
- * E-mail:
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12
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Williams MA, Bouchier JM, Mason AK, Brown PJB. Activation of ChvG-ChvI regulon by cell wall stress confers resistance to β-lactam antibiotics and initiates surface spreading in Agrobacterium tumefaciens. PLoS Genet 2022; 18:e1010274. [PMID: 36480495 PMCID: PMC9731437 DOI: 10.1371/journal.pgen.1010274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 10/28/2022] [Indexed: 12/13/2022] Open
Abstract
A core component of nearly all bacteria, the cell wall is an ideal target for broad spectrum antibiotics. Many bacteria have evolved strategies to sense and respond to antibiotics targeting cell wall synthesis, especially in the soil where antibiotic-producing bacteria compete with one another. Here we show that cell wall stress caused by both chemical and genetic inhibition of the essential, bifunctional penicillin-binding protein PBP1a prevents microcolony formation and activates the canonical host-invasion two-component system ChvG-ChvI in Agrobacterium tumefaciens. Using RNA-seq, we show that depletion of PBP1a for 6 hours results in a downregulation in transcription of flagellum-dependent motility genes and an upregulation in transcription of type VI secretion and succinoglycan biosynthesis genes, a hallmark of the ChvG-ChvI regulon. Depletion of PBP1a for 16 hours, results in differential expression of many additional genes and may promote a stress response, resembling those of sigma factors in other bacteria. Remarkably, the overproduction of succinoglycan causes cell spreading and deletion of the succinoglycan biosynthesis gene exoA restores microcolony formation. Treatment with cefsulodin phenocopies depletion of PBP1a and we correspondingly find that chvG and chvI mutants are hypersensitive to cefsulodin. This hypersensitivity only occurs in response to treatment with β-lactam antibiotics, suggesting that the ChvG-ChvI pathway may play a key role in resistance to antibiotics targeting cell wall synthesis. Finally, we provide evidence that ChvG-ChvI likely has a conserved role in conferring resistance to cell wall stress within the Alphaproteobacteria that is independent of the ChvG-ChvI repressor ExoR.
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Affiliation(s)
- Michelle A. Williams
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri, United States of America
| | - Jacob M. Bouchier
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri, United States of America
| | - Amara K. Mason
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri, United States of America
| | - Pamela J. B. Brown
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, Missouri, United States of America
- * E-mail:
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13
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Quintero-Yanes A, Mayard A, Hallez R. The two-component system ChvGI maintains cell envelope homeostasis in Caulobacter crescentus. PLoS Genet 2022; 18:e1010465. [PMID: 36480504 PMCID: PMC9731502 DOI: 10.1371/journal.pgen.1010465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 10/09/2022] [Indexed: 12/13/2022] Open
Abstract
Two-component systems (TCS) are often used by bacteria to rapidly assess and respond to environmental changes. The ChvG/ChvI (ChvGI) TCS conserved in α-proteobacteria is known for regulating expression of genes related to exopolysaccharide production, virulence and growth. The sensor kinase ChvG autophosphorylates upon yet unknown signals and phosphorylates the response regulator ChvI to regulate transcription. Recent studies in Caulobacter crescentus showed that chv mutants are sensitive to vancomycin treatment and fail to grow in synthetic minimal media. In this work, we identified the osmotic imbalance as the main cause of growth impairment in synthetic minimal media. We also determined the ChvI regulon and found that ChvI regulates cell envelope architecture by controlling outer membrane, peptidoglycan assembly/recycling and inner membrane proteins. In addition, we found that ChvI phosphorylation is also activated upon antibiotic treatment with vancomycin. We also challenged chv mutants with other cell envelope related stress and found that treatment with antibiotics targeting transpeptidation of peptidoglycan during cell elongation impairs growth of the mutant. Finally, we observed that the sensor kinase ChvG relocates from a patchy-spotty distribution to distinctive foci after transition from complex to synthetic minimal media. Interestingly, this pattern of (re)location has been described for proteins involved in cell growth control and peptidoglycan synthesis upon osmotic shock. Overall, our data support that the ChvGI TCS is mainly used to monitor and respond to osmotic imbalances and damages in the peptidoglycan layer to maintain cell envelope homeostasis.
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Affiliation(s)
- Alex Quintero-Yanes
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), University of Namur, Namur, Belgium
| | - Aurélie Mayard
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), University of Namur, Namur, Belgium
| | - Régis Hallez
- Bacterial Cell cycle & Development (BCcD), Biology of Microorganisms Research Unit (URBM), Namur Research Institute for Life Science (NARILIS), University of Namur, Namur, Belgium
- WELBIO, University of Namur, Namur, Belgium
- * E-mail:
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14
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The regulon of Brucella abortus two-component system BvrR/BvrS reveals the coordination of metabolic pathways required for intracellular life. PLoS One 2022; 17:e0274397. [PMID: 36129877 PMCID: PMC9491525 DOI: 10.1371/journal.pone.0274397] [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: 03/30/2022] [Accepted: 08/26/2022] [Indexed: 11/19/2022] Open
Abstract
Brucella abortus is a facultative intracellular pathogen causing a severe zoonotic disease worldwide. The two-component regulatory system (TCS) BvrR/BvrS of B. abortus is conserved in members of the Alphaproteobacteria class. It is related to the expression of genes required for host interaction and intracellular survival. Here we report that bvrR and bvrS are part of an operon composed of 16 genes encoding functions related to nitrogen metabolism, DNA repair and recombination, cell cycle arrest, and stress response. Synteny of this genomic region within close Alphaproteobacteria members suggests a conserved role in coordinating the expression of carbon and nitrogen metabolic pathways. In addition, we performed a ChIP-Seq analysis after exposure of bacteria to conditions that mimic the intracellular environment. Genes encoding enzymes at metabolic crossroads of the pentose phosphate shunt, gluconeogenesis, cell envelope homeostasis, nucleotide synthesis, cell division, and virulence are BvrR/BvrS direct targets. A 14 bp DNA BvrR binding motif was found and investigated in selected gene targets such as virB1, bvrR, pckA, omp25, and tamA. Understanding gene expression regulation is essential to elucidate how Brucella orchestrates a physiological response leading to a furtive pathogenic strategy.
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15
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Tiwari M, Mishra AK, Chakrabarty D. Agrobacterium-mediated gene transfer: recent advancements and layered immunity in plants. PLANTA 2022; 256:37. [PMID: 35819629 PMCID: PMC9274631 DOI: 10.1007/s00425-022-03951-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 06/19/2022] [Indexed: 05/15/2023]
Abstract
Plant responds to Agrobacterium via three-layered immunity that determines its susceptibility or resistance to Agrobacterium infection. Agrobacterium tumefaciens is a soil-borne Gram-negative bacterium that causes crown gall disease in plants. The remarkable feat of interkingdom gene transfer has been extensively utilised in plant biotechnology to transform plant as well as non-host systems. In the past two decades, the molecular mode of the pathogenesis of A. tumefaciens has been extensively studied. Agrobacterium has also been utilised as a premier model to understand the defence response of plants during plant-Agrobacterium interaction. Nonetheless, the threat of Agrobacterium-mediated crown gall disease persists and is associated with a huge loss of plant vigour in agriculture. Understanding the molecular dialogues between these two interkingdom species might provide a cure for crown gall disease. Plants respond to A. tumefaciens by mounting a three-layered immune response, which is manipulated by Agrobacterium via its virulence effector proteins. Comparative studies on plant defence proteins versus the counter-defence of Agrobacterium have shed light on plant susceptibility and tolerance. It is possible to manipulate a plant's immune system to overcome the crown gall disease and increase its competence via A. tumefaciens-mediated transformation. This review summarises the recent advances in the molecular mode of Agrobacterium pathogenesis as well as the three-layered immune response of plants against Agrobacterium infection.
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Affiliation(s)
- Madhu Tiwari
- Biotechnology and Molecular Biology Division, CSIR-National Botanical Research Institute, Lucknow, 226001, India
- Laboratory of Microbial Genetics, Department of Botany, Banaras Hindu University, Varanasi, 221005, India
| | - Arun Kumar Mishra
- Laboratory of Microbial Genetics, Department of Botany, Banaras Hindu University, Varanasi, 221005, India
| | - Debasis Chakrabarty
- Biotechnology and Molecular Biology Division, CSIR-National Botanical Research Institute, Lucknow, 226001, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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16
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Jailani A, Ahmed B, Lee JH, Lee J. Inhibition of Agrobacterium tumefaciens Growth and Biofilm Formation by Tannic Acid. Biomedicines 2022; 10:biomedicines10071619. [PMID: 35884920 PMCID: PMC9312696 DOI: 10.3390/biomedicines10071619] [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: 06/06/2022] [Revised: 07/04/2022] [Accepted: 07/04/2022] [Indexed: 12/04/2022] Open
Abstract
Agrobacterium tumefaciens underlies the pathogenesis of crown gall disease and is characterized by tumor-like gall formation on the stems and roots of a wide variety of economically important plant species. The bacterium initiates infection by colonizing and forming biofilms on plant surfaces, and thus, novel compounds are required to prevent its growth and biofilm formation. In this study, we investigated the ability of tannic acid, which is ubiquitously present in woody plants, to specifically inhibit the growth and biofilm formation of A. tumefaciens. Tannic acid showed antibacterial activity and significantly reduced the biofilm formation on polystyrene and on the roots of Raphanus sativus as determined by 3D bright-field and scanning electron microscopy (SEM) images. Furthermore, tannic acid dose-dependently reduced the virulence features of A. tumefaciens, which are swimming motility, exopolysaccharide production, protease production, and cell surface hydrophobicity. Transcriptional analysis of cells (Abs600 nm = 1.0) incubated with tannic acid for 24 h at 30 °C showed tannic acid most significantly downregulated the exoR gene, which is required for adhesion to surfaces. Tannic acid at 100 or 200 µg/mL limited the iron supply to A. tumefaciens and similarly reduced the biofilm formation to that performed by 0.1 mM EDTA. Notably, tannic acid did not significantly affect R. sativus germination even at 400 µg/mL. The findings of this study suggest that tannic acid has the potential to prevent growth and biofilm formation by A. tumefaciens and thus infections resulting from A. tumefaciens colonization.
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Affiliation(s)
| | | | | | - Jintae Lee
- Correspondence: ; Tel.: +82-53-810-2533; Fax: +82-53-810-4631
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17
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Lakey BD, Myers KS, Alberge F, Mettert EL, Kiley PJ, Noguera DR, Donohue TJ. The essential Rhodobacter sphaeroides CenKR two-component system regulates cell division and envelope biosynthesis. PLoS Genet 2022; 18:e1010270. [PMID: 35767559 PMCID: PMC9275681 DOI: 10.1371/journal.pgen.1010270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 07/12/2022] [Accepted: 05/20/2022] [Indexed: 12/13/2022] Open
Abstract
Bacterial two-component systems (TCSs) often function through the detection of an extracytoplasmic stimulus and the transduction of a signal by a transmembrane sensory histidine kinase. This kinase then initiates a series of reversible phosphorylation modifications to regulate the activity of a cognate, cytoplasmic response regulator as a transcription factor. Several TCSs have been implicated in the regulation of cell cycle dynamics, cell envelope integrity, or cell wall development in Escherichia coli and other well-studied Gram-negative model organisms. However, many α-proteobacteria lack homologs to these regulators, so an understanding of how α-proteobacteria orchestrate extracytoplasmic events is lacking. In this work we identify an essential TCS, CenKR (Cell envelope Kinase and Regulator), in the α-proteobacterium Rhodobacter sphaeroides and show that modulation of its activity results in major morphological changes. Using genetic and biochemical approaches, we dissect the requirements for the phosphotransfer event between CenK and CenR, use this information to manipulate the activity of this TCS in vivo, and identify genes that are directly and indirectly controlled by CenKR in Rb. sphaeroides. Combining ChIP-seq and RNA-seq, we show that the CenKR TCS plays a direct role in maintenance of the cell envelope, regulates the expression of subunits of the Tol-Pal outer membrane division complex, and indirectly modulates the expression of peptidoglycan biosynthetic genes. CenKR represents the first TCS reported to directly control the expression of Tol-Pal machinery genes in Gram-negative bacteria, and we predict that homologs of this TCS serve a similar function in other closely related organisms. We propose that Rb. sphaeroides genes of unknown function that are directly regulated by CenKR play unknown roles in cell envelope biosynthesis, assembly, and/or remodeling in this and other α-proteobacteria. The bacterial cell envelope is home to an array of important functions including energy conservation, motility, influx/efflux of nutrients and toxins, modulation of cell morphology and division, cell-cell interaction, and biofilm formation. Consequently, it is a major target of antibiotics and antimicrobial agents that inhibit these essential processes. Key to the recognition of environmental stressors or stimuli are bacterial TCSs, however systems that monitor or directly regulate cell envelope assembly and homeostasis are not widely conserved amongst bacteria. Here, we use Rhodobacter sphaeroides as a model to investigate the function of the CenKR TCS in this and other α-proteobacteria. We show that this essential TCS plays a key role in maintenance of the cell envelope through the regulation of outer membrane integrity and division, cell wall remodeling and homeostasis, and an alternate sigma factor that controls global cellular stress response. We provide evidence that this TCS and its function is widely conserved in α-proteobacteria and identify genes of unknown function as candidates for the study of cell envelope assembly in this and related bacteria.
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Affiliation(s)
- Bryan D. Lakey
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Kevin S. Myers
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - François Alberge
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Erin L. Mettert
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Patricia J. Kiley
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Daniel R. Noguera
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Timothy J. Donohue
- Wisconsin Energy Institute, Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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18
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Gao M, Liu Z, Zhao Z, Wang Z, Hu X, Jiang Y, Yan J, Li Z, Zheng Z, Zhan X. Exopolysaccharide synthesis repressor genes (exoR and exoX) related to curdlan biosynthesis by Agrobacterium sp. Int J Biol Macromol 2022; 205:193-202. [PMID: 35181324 DOI: 10.1016/j.ijbiomac.2022.02.063] [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: 10/27/2021] [Revised: 01/20/2022] [Accepted: 02/12/2022] [Indexed: 11/25/2022]
Abstract
Curdlan is a neutral, water-insoluble, unbranched, linear β-(1,3)-glucan. This study explored the roles of exoR and exoX in curdlan biosynthesis in Agrobacterium sp. ATCC 31749. The microcapsule biosynthesis of ΔexoR strain was reduced, and the motility of this strain increased remarkably compared with the wild-type (WT) strain during the cell growth phase. The curdlan yields of ΔexoR and ΔexoX strains enhanced by 19% and 17%, and the glucose utilization increased by 12% and 11%, respectively, compared with the WT strain during batch fermentation. By contrast, the curdlan yields of exoR and exoX overexpression strains decreased by 28% and 33%, respectively. The gel strength produced by ΔexoR and exoX overexpression strains decreased compared with the WT strain. RT-qPCR analysis at the transcriptional level revealed that key genes in exopolysaccharide synthesis and central metabolic pathways were up-regulated in ΔexoX and ΔexoR strains during gel production. Metabolomics analysis of ΔexoR and ΔexoX mutants proved the rates of central metabolic and electron transport chain were accelerated.
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Affiliation(s)
- Minjie Gao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, PR China
| | - Zhilei Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, PR China
| | - Zhongsheng Zhao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, PR China
| | - Zichao Wang
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, PR China
| | - Xiuyu Hu
- China Biotech Fermentation Industry Association, Beijing 100833, PR China
| | - Yun Jiang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, PR China
| | - Jiajun Yan
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, PR China
| | - Zhitao Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, PR China
| | - Zhiyong Zheng
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, PR China; Jiangsu Key Laboratory of Anaerobic Biotechnology, Jiangnan University, Wuxi 214122, PR China.
| | - Xiaobei Zhan
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, PR China.
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19
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Wu HY, Lai EM. AGROBEST: A Highly Efficient Agrobacterium-Mediated Transient Expression System in Arabidopsis Seedlings. Methods Mol Biol 2022; 2379:113-123. [PMID: 35188659 DOI: 10.1007/978-1-0716-1791-5_7] [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] [Indexed: 06/14/2023]
Abstract
Agrobacterium-mediated transient transformation for gene expression is a simple and fast method to analyze transgene functions in plants. Agroinfiltration in leaves of Nicotiana benthamiana is a common method for transient expression. However, agroinfiltration in leaves of Arabidopsis thaliana is challenging due to the low and variable efficiency. Here, we describe procedures of a highly efficient and robust Agrobacterium-mediated transient expression system, named AGROBEST (Agrobacterium-mediated enhanced seedling transformation) for gene expression in A. thaliana seedlings. High efficiency of AGROBEST has been achieved by virulence (vir) gene pre-induction of a specific disarmed Agrobacterium tumefaciens strain C58C1(pTiB6S3ΔT)H followed by co-cultivation with Arabidopsis seedlings in an optimized medium with AB salts and buffered acidic plant culture medium. The stable acidic medium largely increases Agrobacterium-mediated transient expression levels and reduces plant defense responses, suggesting that AGROBEST enables high transient expression efficiency by compromising plant immunity. In summary, AGROBEST is a simple, fast, reliable, and robust transient expression system offering a quick and convenient method to observe protein localization, protein-protein interactions, promoter activities, and gene functional studies in Arabidopsis seedlings.
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Affiliation(s)
- Hung-Yi Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Department of Plant Pathology and Microbiology, National Taiwan University, Taipei, Taiwan
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.
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20
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Czolkoss S, Safronov X, Rexroth S, Knoke LR, Aktas M, Narberhaus F. Agrobacterium tumefaciens Type IV and Type VI Secretion Systems Reside in Detergent-Resistant Membranes. Front Microbiol 2021; 12:754486. [PMID: 34899640 PMCID: PMC8656257 DOI: 10.3389/fmicb.2021.754486] [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: 08/06/2021] [Accepted: 10/25/2021] [Indexed: 11/17/2022] Open
Abstract
Cell membranes are not homogenous but compartmentalized into lateral microdomains, which are considered as biochemical reaction centers for various physiological processes in eukaryotes and prokaryotes. Due to their special lipid and protein composition, some of these microdomains are resistant to treatment with non-ionic detergents and can be purified as detergent-resistant membranes (DRMs). Here we report the proteome of DRMs from the Gram-negative phytopathogen Agrobacterium tumefaciens. Using label-free liquid chromatography-tandem mass spectrometry, we identified proteins enriched in DRMs isolated under normal and virulence-mimicking growth conditions. Prominent microdomain marker proteins such as the SPFH (stomatin/prohibitin/flotillin/HflKC) proteins HflK, HflC and Atu3772, along with the protease FtsH were highly enriched in DRMs isolated under any given condition. Moreover, proteins involved in cell envelope biogenesis, transport and secretion, as well as motility- and chemotaxis-associated proteins were overrepresented in DRMs. Most strikingly, we found virulence-associated proteins such as the VirA/VirG two-component system, and the membrane-spanning type IV and type VI secretion systems enriched in DRMs. Fluorescence microscopy of the cellular localization of both secretion systems and of marker proteins was in agreement with the results from the proteomics approach. These findings suggest that virulence traits are micro-compartmentalized into functional microdomains in A. tumefaciens.
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Affiliation(s)
- Simon Czolkoss
- Department of Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | - Xenia Safronov
- Department of Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | - Sascha Rexroth
- Department of Plant Biochemistry, Ruhr University Bochum, Bochum, Germany
| | - Lisa R Knoke
- Department of Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | - Meriyem Aktas
- Department of Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | - Franz Narberhaus
- Department of Microbial Biology, Ruhr University Bochum, Bochum, Germany
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21
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Lin J, Xu L, Yang J, Wang Z, Shen X. Beyond dueling: roles of the type VI secretion system in microbiome modulation, pathogenesis and stress resistance. STRESS BIOLOGY 2021; 1:11. [PMID: 37676535 PMCID: PMC10441901 DOI: 10.1007/s44154-021-00008-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 08/09/2021] [Indexed: 09/08/2023]
Abstract
Bacteria inhabit diverse and dynamic environments, where nutrients may be limited and toxic chemicals can be prevalent. To adapt to these stressful conditions, bacteria have evolved specialized protein secretion systems, such as the type VI secretion system (T6SS) to facilitate their survival. As a molecular syringe, the T6SS expels various effectors into neighboring bacterial cells, eukaryotic cells, or the extracellular environment. These effectors improve the competitive fitness and environmental adaption of bacterial cells. Although primarily recognized as antibacterial weapons, recent studies have demonstrated that T6SSs have functions beyond interspecies competition. Here, we summarize recent research on the role of T6SSs in microbiome modulation, pathogenesis, and stress resistance.
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Affiliation(s)
- Jinshui Lin
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, Shaanxi, 716000, People's Republic of China
| | - Lei Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China
| | - Jianshe Yang
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan'an University, Yan'an, Shaanxi, 716000, People's Republic of China
| | - Zhuo Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, People's Republic of China.
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22
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Wu CF, Weisberg AJ, Davis EW, Chou L, Khan S, Lai EM, Kuo CH, Chang JH. Diversification of the Type VI Secretion System in Agrobacteria. mBio 2021; 12:e0192721. [PMID: 34517758 PMCID: PMC8546570 DOI: 10.1128/mbio.01927-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/16/2021] [Indexed: 12/13/2022] Open
Abstract
The type VI secretion system (T6SS) is used by many Gram-negative bacteria to deploy toxic effectors for interbacterial competition. This system provides a competitive advantage in planta to agrobacteria, a diverse group with phytopathogenic members capable of genetically transforming plants. To inform on the ecology and evolution of agrobacteria, we revealed processes that diversify their effector gene collections. From genome sequences of diverse strains, we identified T6SS loci, functionally validated associated effector genes for toxicity, and predicted genes homologous to those that encode proteins known to interact with effectors. The gene loci were analyzed in a phylogenetic framework, and results show that strains of some species-level groups have different patterns of T6SS expression and are enriched in specific sets of T6SS loci. Findings also demonstrate that the modularity of T6SS loci and their associated genes engenders dynamicity, promoting reshuffling of entire loci, fragments therein, and domains to swap toxic effector genes across species. However, diversification is constrained by the need to maintain specific combinations of gene subtypes, congruent with observations that certain genes function together to regulate T6SS loading and activation. Data are consistent with a scenario where species can acquire unique T6SS loci that are then reshuffled across the genus in a restricted manner to generate new combinations of effector genes. IMPORTANCE The T6SS is used by several taxa of Gram-negative bacteria to secrete toxic effector proteins to attack others. Diversification of effector collections shapes bacterial interactions and impacts the health of hosts and ecosystems in which bacteria reside. We uncovered the diversity of T6SS loci across a genus of plant-associated bacteria and show that diversification is driven by the acquisition of new loci and reshuffling among species. However, linkages between specific subtypes of genes need to be maintained to ensure that proteins whose interactions are necessary to activate the T6SS remain together. Results reveal how organization of gene loci and domain structure of genes provides flexibility to diversify under the constraints imposed by the system. Findings inform on the evolution of a mechanism that influences bacterial communities.
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Affiliation(s)
- Chih-Feng Wu
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Alexandra J. Weisberg
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Edward W. Davis
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
- Molecular and Cellular Biology Program, Oregon State University, Corvallis, Oregon, USA
| | - Lin Chou
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Surtaz Khan
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Chih-Horng Kuo
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Jeff H. Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
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Alakavuklar MA, Heckel BC, Stoner AM, Stembel JA, Fuqua C. Motility control through an anti-activation mechanism in Agrobacterium tumefaciens. Mol Microbiol 2021; 116:1281-1297. [PMID: 34581467 DOI: 10.1111/mmi.14823] [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: 06/23/2021] [Revised: 09/22/2021] [Accepted: 09/24/2021] [Indexed: 12/14/2022]
Abstract
Many bacteria can migrate from a free-living, planktonic state to an attached, biofilm existence. One factor regulating this transition in the facultative plant pathogen Agrobacterium tumefaciens is the ExoR-ChvG-ChvI system. Periplasmic ExoR regulates the activity of the ChvG-ChvI two-component system in response to environmental stress, most notably low pH. ChvI impacts hundreds of genes, including those required for type VI secretion, virulence, biofilm formation, and flagellar motility. Previous studies revealed that activated ChvG-ChvI represses expression of most of class II and class III flagellar biogenesis genes, but not the master motility regulator genes visN, visR, and rem. In this study, we characterized the integration of the ExoR-ChvG-ChvI and VisNR-Rem pathways. We isolated motile suppressors of the non-motile ΔexoR mutant and thereby identified the previously unannotated mirA gene encoding a 76 amino acid protein. We report that the MirA protein interacts directly with the Rem DNA-binding domain, sequestering Rem and preventing motility gene activation. The ChvG-ChvI pathway activates mirA expression and elevated mirA is sufficient to block motility. This study reveals how the ExoR-ChvG-ChvI pathway prevents flagellar motility in A. tumefaciens. MirA is also conserved among other members of the Rhizobiales suggesting similar mechanisms of motility regulation.
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Affiliation(s)
| | - Brynn C Heckel
- Indiana University, Bloomington, Indiana, USA.,California State University, Dominguez Hills, Carson, California, USA
| | - Ari M Stoner
- Indiana University, Bloomington, Indiana, USA.,Indiana University Medical School, Indianapolis, Indiana, USA
| | - Joseph A Stembel
- Indiana University, Bloomington, Indiana, USA.,University of Washington, Seattle, Washington, USA
| | - Clay Fuqua
- Indiana University, Bloomington, Indiana, USA
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24
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The ChvG-ChvI and NtrY-NtrX Two-Component Systems Coordinately Regulate Growth of Caulobacter crescentus. J Bacteriol 2021; 203:e0019921. [PMID: 34124942 DOI: 10.1128/jb.00199-21] [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] [Indexed: 12/17/2022] Open
Abstract
Two-component signaling systems (TCSs) are comprised of a sensory histidine kinase and a response regulator protein. In response to environmental changes, sensor kinases directly phosphorylate their cognate response regulator to affect gene expression. Bacteria typically express multiple TCSs that are insulated from one another and regulate distinct physiological processes. There are examples of cross-regulation between TCSs, but this phenomenon remains relatively unexplored. We have identified regulatory links between the ChvG-ChvI (ChvGI) and NtrY-NtrX (NtrYX) TCSs, which control important and often overlapping processes in alphaproteobacteria, including maintenance of the cell envelope. Deletion of chvG and chvI in Caulobacter crescentus limited growth in defined medium, and a selection for genetic suppressors of this growth phenotype uncovered interactions among chvGI, ntrYX, and ntrZ, which encodes a previously uncharacterized periplasmic protein. Significant overlap in the experimentally defined ChvI and NtrX transcriptional regulons provided support for the observed genetic connections between ntrYX and chvGI. Moreover, we present evidence that the growth defect of strains lacking chvGI is influenced by the phosphorylation state of NtrX and, to some extent, by levels of the TonB-dependent receptor ChvT. Measurements of NtrX phosphorylation in vivo indicated that NtrZ is an upstream regulator of NtrY and that NtrY primarily functions as an NtrX phosphatase. We propose a model in which NtrZ functions in the periplasm to inhibit NtrY phosphatase activity; regulation of phosphorylated NtrX levels by NtrZ and NtrY provides a mechanism to modulate and balance expression of the NtrX and ChvI regulons under different growth conditions. IMPORTANCE TCSs enable bacteria to regulate gene expression in response to physiochemical changes in their environment. The ChvGI and NtrYX TCSs regulate diverse pathways associated with pathogenesis, growth, and cell envelope function in many alphaproteobacteria. We used Caulobacter crescentus as a model to investigate regulatory connections between ChvGI and NtrYX. Our work defined the ChvI transcriptional regulon in C. crescentus and revealed a genetic interaction between ChvGI and NtrYX, whereby modulation of NtrYX signaling affects the survival of cells lacking ChvGI. In addition, we identified NtrZ as a periplasmic inhibitor of NtrY phosphatase activity in vivo. Our work establishes C. crescentus as an excellent model to investigate multilevel regulatory connections between ChvGI and NtrYX in alphaproteobacteria.
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Geiger O, Sohlenkamp C, Vera-Cruz D, Medeot DB, Martínez-Aguilar L, Sahonero-Canavesi DX, Weidner S, Pühler A, López-Lara IM. ExoS/ChvI Two-Component Signal-Transduction System Activated in the Absence of Bacterial Phosphatidylcholine. FRONTIERS IN PLANT SCIENCE 2021; 12:678976. [PMID: 34367203 PMCID: PMC8343143 DOI: 10.3389/fpls.2021.678976] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
Sinorhizobium meliloti contains the negatively charged phosphatidylglycerol and cardiolipin as well as the zwitterionic phosphatidylethanolamine (PE) and phosphatidylcholine (PC) as major membrane phospholipids. In previous studies we had isolated S. meliloti mutants that lack PE or PC. Although mutants deficient in PE are able to form nitrogen-fixing nodules on alfalfa host plants, mutants lacking PC cannot sustain development of any nodules on host roots. Transcript profiles of mutants unable to form PE or PC are distinct; they differ from each other and they are different from the wild type profile. For example, a PC-deficient mutant of S. meliloti shows an increase of transcripts that encode enzymes required for succinoglycan biosynthesis and a decrease of transcripts required for flagellum formation. Indeed, a PC-deficient mutant is unable to swim and overproduces succinoglycan. Some suppressor mutants, that regain swimming and form normal levels of succinoglycan, are altered in the ExoS sensor. Our findings suggest that the lack of PC in the sinorhizobial membrane activates the ExoS/ChvI two-component regulatory system. ExoS/ChvI constitute a molecular switch in S. meliloti for changing from a free-living to a symbiotic life style. The periplasmic repressor protein ExoR controls ExoS/ChvI function and it is thought that proteolytic ExoR degradation would relieve repression of ExoS/ChvI thereby switching on this system. However, as ExoR levels are similar in wild type, PC-deficient mutant and suppressor mutants, we propose that lack of PC in the bacterial membrane provokes directly a conformational change of the ExoS sensor and thereby activation of the ExoS/ChvI two-component system.
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Affiliation(s)
- Otto Geiger
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Christian Sohlenkamp
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Diana Vera-Cruz
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Daniela B. Medeot
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | | | | | - Stefan Weidner
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Alfred Pühler
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Isabel M. López-Lara
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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Host-Like Conditions Are Required for T6SS-Mediated Competition among Vibrio fischeri Light Organ Symbionts. mSphere 2021; 6:e0128820. [PMID: 34287008 PMCID: PMC8386388 DOI: 10.1128/msphere.01288-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Bacteria employ diverse competitive strategies to enhance fitness and promote their own propagation. However, little is known about how symbiotic bacteria modulate competitive mechanisms as they compete for a host niche. The bacterium Vibrio fischeri forms a symbiotic relationship with marine animals and encodes a type VI secretion system (T6SS), which is a contact-dependent killing mechanism used to eliminate competitors during colonization of the Euprymna scolopes squid light organ. Like other horizontally acquired symbionts, V. fischeri experiences changes in its physical and chemical environment during symbiosis establishment. Therefore, we probed both environmental and host-like conditions to identify ecologically relevant cues that control T6SS-dependent competition during habitat transition. Although the T6SS did not confer a competitive advantage for V. fischeri strain ES401 under planktonic conditions, a combination of both host-like pH and viscosity was necessary for T6SS competition. For ES401, high viscosity activates T6SS expression and neutral/acidic pH promotes cell-cell contact for killing, and this pH-dependent phenotype was conserved in the majority of T6SS-encoding strains examined. We also identified a subset of V. fischeri isolates that engaged in T6SS-mediated competition at high viscosity under both planktonic and host-like pH conditions. T6SS phylogeny revealed that strains with pH-dependent phenotypes cluster together to form a subclade within the pH-independent strains, suggesting that V. fischeri may have recently evolved to limit competition to the host niche. IMPORTANCE Bacteria have evolved diverse strategies to compete for limited space and resources. Because these mechanisms can be costly to use, their expression and function are often restricted to specific environments where the benefits outweigh the costs. However, little is known about the specific cues that modulate competitive mechanisms as bacterial symbionts transition between free-living and host habitats. Here, we used the bioluminescent squid and fish symbiont Vibrio fischeri to probe for host and environmental conditions that control interbacterial competition via the type VI secretion system. Our findings identify a new host-specific cue that promotes competition among many but not all V. fischeri isolates, underscoring the utility of studying multiple strains to reveal how competitive mechanisms may be differentially regulated among closely related populations as they evolve to fill distinct niches.
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27
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Borrero de Acuña JM, Bernal P. Plant holobiont interactions mediated by the type VI secretion system and the membrane vesicles: promising tools for a greener agriculture. Environ Microbiol 2021; 23:1830-1836. [PMID: 33687778 DOI: 10.1111/1462-2920.15457] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/03/2021] [Accepted: 03/05/2021] [Indexed: 12/15/2022]
Abstract
A deeper understanding of the complex relationship between plants and their microbiota is allowing researchers to appreciate a plethora of possibilities to improve crops using chemical-free alternatives based on beneficial microorganisms. An increase in crop yield from the promotion of plant growth or even simultaneous protection of the plants from the attack of phytopathogens can be achieved in the presence of different plant-associated microorganisms known as plant-growth-promoting rhizobacteria (PGPR) and biocontrol agents (BCAs), respectively. Thus, the study of the great diversity of plant-microbe and microbe-microbe interactions is an attention-grabbing topic covering studies of interactions since the plant seed and through all developmental stages, from root to shoot. The intricate communication systems that plant holobionts co-evolved has resulted in many different strategies and interplays between these organisms shaping the bacterial communities and the plant fitness simultaneously. Herein, we emphasize two understudied delivery systems existing in plant-associated bacteria: the type VI secretion system (T6SS) and the membrane vesicles with a huge potential to boost a highly demanded and necessary green agriculture.
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Affiliation(s)
- José Manuel Borrero de Acuña
- Institute of Microbiology, Technische Universität Braunschweig, Braunschweig, Germany.,Braunschweig Integrated Centre of Systems Biology (BRICS), Technische Universität Braunschweig, Braunschweig, Germany
| | - Patricia Bernal
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Seville, Spain
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28
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Jaboulay C, Godeux AS, Doublet P, Vianney A. Regulatory Networks of the T4SS Control: From Host Cell Sensing to the Biogenesis and the Activity during the Infection. J Mol Biol 2021; 433:166892. [PMID: 33636165 DOI: 10.1016/j.jmb.2021.166892] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/17/2021] [Accepted: 02/17/2021] [Indexed: 02/03/2023]
Abstract
Delivery of effectors, DNA or proteins, that hijack host cell processes to the benefit of bacteria is a mechanism widely used by bacterial pathogens. It is achieved by complex effector injection devices, the secretion systems, among which Type 4 Secretion Systems (T4SSs) play a key role in bacterial virulence of numerous animal and plant pathogens. Considerable progress has recently been made in the structure-function analyses of T4SSs. Nevertheless, the signals and processes that trigger machine assembly and activity during infection, as well as those involved in substrate recognition and transfer, are complex and still poorly understood. In this review, we aim at summarizing the last updates of the knowledge on signaling pathways that regulate the biogenesis and the activity of T4SSs in important bacterial pathogens.
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Affiliation(s)
- C Jaboulay
- CIRI, Centre International de Recherche en Infectiologie, (Team: Legionella pathogenesis), Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, F-69007 Lyon, France.
| | - A S Godeux
- CIRI, Centre International de Recherche en Infectiologie, (Team: Horigene), Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, F-69007 Lyon, France
| | - P Doublet
- CIRI, Centre International de Recherche en Infectiologie, (Team: Legionella pathogenesis), Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, F-69007 Lyon, France
| | - A Vianney
- CIRI, Centre International de Recherche en Infectiologie, (Team: Legionella pathogenesis), Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, F-69007 Lyon, France
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29
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T6SS Mediated Stress Responses for Bacterial Environmental Survival and Host Adaptation. Int J Mol Sci 2021; 22:ijms22020478. [PMID: 33418898 PMCID: PMC7825059 DOI: 10.3390/ijms22020478] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 12/25/2020] [Accepted: 01/01/2021] [Indexed: 02/07/2023] Open
Abstract
The bacterial type VI secretion system (T6SS) is a protein secretion apparatus widely distributed in Gram-negative bacterial species. Many bacterial pathogens employ T6SS to compete with the host and to coordinate the invasion process. The T6SS apparatus consists of a membrane complex and an inner tail tube-like structure that is surrounded by a contractile sheath and capped with a spike complex. A series of antibacterial or antieukaryotic effectors is delivered by the puncturing device consisting of a Hcp tube decorated by the VgrG/PAAR complex into the target following the contraction of the TssB/C sheath, which often leads to damage and death of the competitor and/or host cells. As a tool for protein secretion and interspecies interactions, T6SS can be triggered by many different mechanisms to respond to various physiological conditions. This review summarizes our current knowledge of T6SS in coordinating bacterial stress responses against the unfavorable environmental and host conditions.
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30
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Hu L, Yu F, Liu M, Chen J, Zong B, Zhang Y, Chen T, Wang C, Zhang T, Zhang J, Zhu Y, Wang X, Chen H, Tan C. RcsB-dependent regulation of type VI secretion system in porcine extra-intestinal pathogenic Escherichia coli. Gene 2020; 768:145289. [PMID: 33181257 DOI: 10.1016/j.gene.2020.145289] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 10/26/2020] [Accepted: 10/29/2020] [Indexed: 02/02/2023]
Abstract
Signal transduction system and specialized secretory devices are crucial for bacteria to sense and adequately adapt in adverse environmental conditions. Therefore, it's crucial for microbes to detect and respond to lethal attacks when envelope is perturbed so as to minimize and fix the damage in milieu. We investigated the adaptive response of porcine extra-intestinal pathogenic Escherichia coli PCN033 to polymyxin B challenge. Treatment with polymyxin B led to rapid and robust activation of Rcs system via RcsF, as well as the accumulation of reactive oxygen species. ExPEC T6SS expression was strongly induced by RcsB in Rcs system, resulting in the reduction in the damage to constitute a survival strategy. Finally, we show that T6SS of ExPEC is involved in its pathogenicity in mouse model. Compared with the wild type strain, the deletion of T6SS genes led to a decrease in the organ colonization ability, and the RcsFS2DM3Q mutant that caused Rcs activation had a stronger colonization ability than the wild type strain. In conclusion, Rcs system orchestrates Rcs cascade to trigger antioxidant defense of T6SS, and presents a typical model in which a bacterium reschedule its transcription network via the Rcs phosphorelay pathway in response to membrane perturbations for survival and pathogenesis.
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Affiliation(s)
- Linlin Hu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Feifei Yu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Manli Liu
- Hubei Biopesticide Engineering Research Centre, Hubei Academy of Agricultural Sciences, Wuhan 430064, Hubei, China
| | - Jing Chen
- Guangzhou Medical University, Guangzhou 511436, Guangdong, China
| | - Bingbing Zong
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Yanyan Zhang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Tumei Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Chenchen Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Tongchao Zhang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Junli Zhang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Yongwei Zhu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China
| | - Xiangru Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Centre for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Centre for Sustainable Pig Production, Wuhan, Hubei 430070, China
| | - Chen Tan
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Centre for Sustainable Pig Production, Wuhan, Hubei 430070, China.
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31
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Xia K, Han C, Xu J, Liang X. Transcriptome response of Acetobacter pasteurianus Ab3 to high acetic acid stress during vinegar production. Appl Microbiol Biotechnol 2020; 104:10585-10599. [PMID: 33156446 DOI: 10.1007/s00253-020-10995-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 10/01/2020] [Accepted: 10/31/2020] [Indexed: 12/12/2022]
Abstract
Acetic acid accumulation is a universal limiting factor to the vinegar manufacture because of the toxic effect of acetic acid on the acid producing strain, such as Acetobacter pasteurianus. In this study, we aimed to investigate the genome-wide transcriptional response of A. pasteurianus Ab3 to high acid stress during vinegar production. By comparing the transcriptional landscape of cells harvested from a long-term cultivation with high acidity (70 ± 3 g/L) to that of low acidity (10 ± 2 g/L), we demonstrated that 1005 genes were differentially expressed. By functional enrichment analysis, we found that the expression of genes related to the two-component systems (TCS) and toxin-antitoxin systems (TAS) was significantly regulated under high acid stress. Cells increased the genome stability to withstand the intracellular toxicity caused by the acetic acid accumulation by repressing the expression of transposases and integrases. Moreover, high acid stress induced the expression of genes involved in the pathways of peptidoglycan, ceramide, and phosphatidylcholine biosynthesis as well as the Tol-Pal and TonB-ExbB systems. In addition, we observed that cells increased and diversified the ATP production to resist high acid stress. Transcriptional upregulation in the pathways of pyrroloquinoline quinone (PQQ) synthesis and thiamine metabolism suggested that cells may increase the production of prosthetic groups to ensure the enzyme activity upon high acid stress. Collectively, the results of this study increase our current understanding of the acetic acid resistance (AAR) mechanisms in A. pasteurianus and provide opportunities for strain improvement and scaled-up vinegar production.Key Points• TCS and TAS are responsive to the acid stress and constitute the regulating networks.• Adaptive expression changes of cell envelope elements help cell resist acid stress.• Cells promote genome stability and diversify ATP production to withstand acid stress.
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Affiliation(s)
- Kai Xia
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China
| | - Chengcheng Han
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China
- Institute of Food Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China
| | - Jun Xu
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China
- Institute of Food Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China
| | - Xinle Liang
- School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China.
- Institute of Food Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, China.
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Bernal P, Murillo-Torres M, Allsopp LP. Integrating signals to drive type VI secretion system killing. Environ Microbiol 2020; 22:4520-4523. [PMID: 32990336 DOI: 10.1111/1462-2920.15255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 09/25/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Patricia Bernal
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Marina Murillo-Torres
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Seville, Spain.,National Heart and Lung Institute, Imperial College London, London, UK
| | - Luke P Allsopp
- National Heart and Lung Institute, Imperial College London, London, UK
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Wu C, Lien Y, Bondage D, Lin J, Pilhofer M, Shih Y, Chang JH, Lai E. Effector loading onto the VgrG carrier activates type VI secretion system assembly. EMBO Rep 2020; 21:e47961. [PMID: 31808291 PMCID: PMC6945064 DOI: 10.15252/embr.201947961] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 11/12/2019] [Accepted: 11/15/2019] [Indexed: 01/08/2023] Open
Abstract
The type VI secretion system (T6SS) is used by many bacteria to engage in social behavior and can affect the health of its host plant or animal. Because activities associated with T6SSs are often costly, T6SSs must be tightly regulated. However, our knowledge regarding how T6SS assembly and contraction are regulated remains limited. Using the plant pathogen Agrobacterium tumefaciens, we show that effectors are not just passengers but also impact on T6SS assembly. The A. tumefaciens strain C58 encodes one T6SS and two Tde DNase toxin effectors used as major weapons for interbacterial competition. Here, we demonstrate that loading of Tde effectors onto their cognate carriers, the VgrG spikes, is required for active T6SS secretion. The assembly of the TssBC contractile sheath occurs only in the presence of Tde effectors. The requirement of effector loading for efficient T6SS secretion was also validated in other A. tumefaciens strains. We propose that such a mechanism is used by bacteria as a strategy for efficacious T6SS firing and to ensure that effectors are loaded onto the T6SS prior to completing its assembly.
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Affiliation(s)
- Chih‐Feng Wu
- Institute of Plant and Microbial BiologyAcademia SinicaTaipeiTaiwan
- Department of Botany and Plant PathologyOregon State UniversityCorvallisORUSA
| | - Yun‐Wei Lien
- Institute of Plant and Microbial BiologyAcademia SinicaTaipeiTaiwan
- Department of Plant Pathology and MicrobiologyNational Taiwan UniversityTaipeiTaiwan
- Institute of Molecular Biology & BiophysicsEidgenössische Technische Hochschule ZürichZürichSwitzerland
| | - Devanand Bondage
- Institute of Plant and Microbial BiologyAcademia SinicaTaipeiTaiwan
- Present address:
Division of Molecular and Cellular BiologyEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA
| | - Jer‐Sheng Lin
- Institute of Plant and Microbial BiologyAcademia SinicaTaipeiTaiwan
- Present address:
Department of Organismic InteractionsMax Planck Institute for Terrestrial MicrobiologyMarburgGermany
| | - Martin Pilhofer
- Institute of Molecular Biology & BiophysicsEidgenössische Technische Hochschule ZürichZürichSwitzerland
| | - Yu‐Ling Shih
- Institute of Biological ChemistryAcademia SinicaTaipeiTaiwan
| | - Jeff H Chang
- Department of Botany and Plant PathologyOregon State UniversityCorvallisORUSA
- Center for Genome Research and BiocomputingOregon State UniversityCorvallisORUSA
| | - Erh‐Min Lai
- Institute of Plant and Microbial BiologyAcademia SinicaTaipeiTaiwan
- Department of Plant Pathology and MicrobiologyNational Taiwan UniversityTaipeiTaiwan
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Zhu PC, Li YM, Yang X, Zou HF, Zhu XL, Niu XN, Xu LH, Jiang W, Huang S, Tang JL, He YQ. Type VI secretion system is not required for virulence on rice but for inter-bacterial competition in Xanthomonas oryzae pv. oryzicola. Res Microbiol 2019; 171:64-73. [PMID: 31676435 DOI: 10.1016/j.resmic.2019.10.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 10/17/2019] [Accepted: 10/17/2019] [Indexed: 11/28/2022]
Abstract
The type VI secretion system (T6SS), a multifunctional protein secretion device, plays very important roles in bacterial killing and/or virulence to eukaryotic cells. Although T6SS genes have been found in many Xanthomonas species, the biological function of T6SSs has not been elucidated in most xanthomonads. In this study, we identified two phylogenetically distinct T6SS clusters, T6SS1 and T6SS2, in a newly sequenced Chinese strain GX01 of Xanthomonas oryzea pv. oryzicola (Xoc) which causes bacterial leaf streak (BLS) of rice (Oryza sativa L.). Mutational assays demonstrated that T6SS1 and T6SS2 are not required for the virulence of Xoc GX01 on rice. Nevertheless, we found that T6SS2, but not T6SS1, played an important role in bacterial killing. Transcription and secretion analysis revealed that hcp2 gene is actively expressed and that Hcp2 protein is secreted via T6SS. Moreover, several candidate T6SS effectors were predicted by bioinformatics analysis that might play a role in the antibacterial activity of Xoc. This is the first report to investigate the type VI secretion system in Xanthomonas oryzae. We speculate that Xoc T6SS2 might play an important role in inter-bacterial competition, allowing this plant pathogen to gain niche advantage by killing other bacteria.
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Affiliation(s)
- Ping-Chuan Zhu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China
| | - Yi-Ming Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China
| | - Xia Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China
| | - Hai-Fan Zou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China
| | - Xiao-Lin Zhu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China
| | - Xiang-Na Niu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China
| | - Ling-Hui Xu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China
| | - Wei Jiang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China
| | - Sheng Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China
| | - Ji-Liang Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China.
| | - Yong-Qiang He
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China; National Demonstration Center for Experimental Plant Science Education, College of Agriculture, Guangxi University, 100 Daxue Road, Nanning, Guangxi, 530004, China.
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Wu CF, Santos MNM, Cho ST, Chang HH, Tsai YM, Smith DA, Kuo CH, Chang JH, Lai EM. Plant-Pathogenic Agrobacterium tumefaciens Strains Have Diverse Type VI Effector-Immunity Pairs and Vary in In-Planta Competitiveness. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:961-971. [PMID: 30830835 DOI: 10.1094/mpmi-01-19-0021-r] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The type VI secretion system (T6SS) is used by gram-negative bacteria to translocate effectors that can antagonize other bacterial cells. Models predict the variation in collections of effector and cognate immunity genes determine competitiveness and can affect the dynamics of populations and communities of bacteria. However, the outcomes of competition cannot be entirely explained by compatibility of effector-immunity (EI) pairs. Here, we characterized the diversity of T6SS loci of plant-pathogenic Agrobacterium tumefaciens and showed that factors other than EI pairs can impact interbacterial competition. All examined strains encode T6SS active in secretion and antagonism against Escherichia coli. The spectra of EI pairs as well as compositions of gene neighborhoods are diverse. Almost 30 in-planta competitions were tested between different genotypes of A. tumefaciens. Fifteen competitions between members of different species-level groups resulted in T6SS-dependent suppression in in-planta growth of prey genotypes. In contrast, ten competitions between members within species-level groups resulted in no significant effect on the growth of prey genotypes. One strain was an exceptional case and, despite encoding a functional T6SS and toxic effector protein, could not compromise the growth of the four tested prey genotypes. The data suggest T6SS-associated EI pairs can influence the competitiveness of strains of A. tumefaciens, but genetic features have a significant role on the efficacy of interbacterial antagonism.
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Affiliation(s)
- Chih-Feng Wu
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
- 2Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, U.S.A
| | - Mary Nia M Santos
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Shu-Ting Cho
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Hsing-Hua Chang
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Yi-Ming Tsai
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Delaney A Smith
- 2Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, U.S.A
| | - Chih-Horng Kuo
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Jeff H Chang
- 2Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, U.S.A
- 3Center for Genome Research and Biocomputing, Oregon State University
| | - Erh-Min Lai
- 1Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan
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McCarthy RR, Yu M, Eilers K, Wang Y, Lai E, Filloux A. Cyclic di-GMP inactivates T6SS and T4SS activity in Agrobacterium tumefaciens. Mol Microbiol 2019; 112:632-648. [PMID: 31102484 PMCID: PMC6771610 DOI: 10.1111/mmi.14279] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2019] [Indexed: 01/17/2023]
Abstract
The Type VI secretion system (T6SS) is a bacterial nanomachine that delivers effector proteins into prokaryotic and eukaryotic preys. This secretion system has emerged as a key player in regulating the microbial diversity in a population. In the plant pathogen Agrobacterium tumefaciens, the signalling cascades regulating the activity of this secretion system are poorly understood. Here, we outline how the universal eubacterial second messenger cyclic di-GMP impacts the production of T6SS toxins and T6SS structural components. We demonstrate that this has a significant impact on the ability of the phytopathogen to compete with other bacterial species in vitro and in planta. Our results suggest that, as opposed to other bacteria, c-di-GMP turns down the T6SS in A. tumefaciens thus impacting its ability to compete with other bacterial species within the rhizosphere. We also demonstrate that elevated levels of c-di-GMP within the cell decrease the activity of the Type IV secretion system (T4SS) and subsequently the capacity of A. tumefaciens to transform plant cells. We propose that such peculiar control reflects on c-di-GMP being a key second messenger that silences energy-costing systems during early colonization phase and biofilm formation, while low c-di-GMP levels unleash T6SS and T4SS to advance plant colonization.
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Affiliation(s)
- Ronan R. McCarthy
- MRC Centre for Molecular Bacteriology and Infection, Department of Life SciencesImperial College LondonLondonSW7 2AZUK
- Division of Biosciences, Department of Life SciencesCollege of Health and Life Sciences, Brunel University LondonUxbridgeUB8 3PHUK
| | - Manda Yu
- Institute of Plant and Microbial BiologyAcademia SinicaTaipei11529Taiwan
| | - Kira Eilers
- MRC Centre for Molecular Bacteriology and Infection, Department of Life SciencesImperial College LondonLondonSW7 2AZUK
| | - Yi‐Chieh Wang
- Institute of Plant and Microbial BiologyAcademia SinicaTaipei11529Taiwan
| | - Erh‐Min Lai
- Institute of Plant and Microbial BiologyAcademia SinicaTaipei11529Taiwan
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life SciencesImperial College LondonLondonSW7 2AZUK
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Meyer T, Thiour-Mauprivez C, Wisniewski-Dyé F, Kerzaon I, Comte G, Vial L, Lavire C. Ecological Conditions and Molecular Determinants Involved in Agrobacterium Lifestyle in Tumors. FRONTIERS IN PLANT SCIENCE 2019; 10:978. [PMID: 31417593 PMCID: PMC6683767 DOI: 10.3389/fpls.2019.00978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 07/11/2019] [Indexed: 05/07/2023]
Abstract
The study of pathogenic agents in their natural niches allows for a better understanding of disease persistence and dissemination. Bacteria belonging to the Agrobacterium genus are soil-borne and can colonize the rhizosphere. These bacteria are also well known as phytopathogens as they can cause tumors (crown gall disease) by transferring a DNA region (T-DNA) into a wide range of plants. Most reviews on Agrobacterium are focused on virulence determinants, T-DNA integration, bacterial and plant factors influencing the efficiency of genetic transformation. Recent research papers have focused on the plant tumor environment on the one hand, and genetic traits potentially involved in bacterium-plant interactions on the other hand. The present review gathers current knowledge about the special conditions encountered in the tumor environment along with the Agrobacterium genetic determinants putatively involved in bacterial persistence inside a tumor. By integrating recent metabolomic and transcriptomic studies, we describe how tumors develop and how Agrobacterium can maintain itself in this nutrient-rich but stressful and competitive environment.
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Affiliation(s)
- Thibault Meyer
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
| | - Clémence Thiour-Mauprivez
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
- Biocapteurs-Analyses-Environment, Universite de Perpignan Via Domitia, Perpignan, France
- Laboratoire de Biodiversite et Biotechnologies Microbiennes, USR 3579 Sorbonne Universites (UPMC) Paris 6 et CNRS Observatoire Oceanologique, Paris, France
| | | | - Isabelle Kerzaon
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
| | - Gilles Comte
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
| | - Ludovic Vial
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
| | - Céline Lavire
- UMR Ecologie Microbienne, CNRS, INRA, VetAgro Sup, UCBL, Université de Lyon, Lyon, France
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Thompson MA, Onyeziri MC, Fuqua C. Function and Regulation of Agrobacterium tumefaciens Cell Surface Structures that Promote Attachment. Curr Top Microbiol Immunol 2019; 418:143-184. [PMID: 29998422 PMCID: PMC6330146 DOI: 10.1007/82_2018_96] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Agrobacterium tumefaciens attaches stably to plant host tissues and abiotic surfaces. During pathogenesis, physical attachment to the site of infection is a prerequisite to infection and horizontal gene transfer to the plant. Virulent and avirulent strains may also attach to plant tissue in more benign plant associations, and as with other soil microbes, to soil surfaces in the terrestrial environment. Although most A. tumefaciens virulence functions are encoded on the tumor-inducing plasmid, genes that direct general surface attachment are chromosomally encoded, and thus this process is not obligatorily tied to virulence, but is a more fundamental capacity. Several different cellular structures are known or suspected to contribute to the attachment process. The flagella influence surface attachment primarily via their propulsive activity, but control of their rotation during the transition to the attached state may be quite complex. A. tumefaciens produces several pili, including the Tad-type Ctp pili, and several plasmid-borne conjugal pili encoded by the Ti and At plasmids, as well as the so-called T-pilus, involved in interkingdom horizontal gene transfer. The Ctp pili promote reversible interactions with surfaces, whereas the conjugal and T-pili drive horizontal gene transfer (HGT) interactions with other cells and tissues. The T-pilus is likely to contribute to physical association with plant tissues during DNA transfer to plants. A. tumefaciens can synthesize a variety of polysaccharides including cellulose, curdlan (β-1,3 glucan), β-1,2 glucan (cyclic and linear), succinoglycan, and a localized polysaccharide(s) that is confined to a single cellular pole and is called the unipolar polysaccharide (UPP). Lipopolysaccharides are also in the outer leaflet of the outer membrane. Cellulose and curdlan production can influence attachment under certain conditions. The UPP is required for stable attachment under a range of conditions and on abiotic and biotic surfaces. Other factors that have been reported to play a role in attachment include the elusive protein called rhicadhesin. The process of surface attachment is under extensive regulatory control and can be modulated by environmental conditions, as well as by direct responses to surface contact. Complex transcriptional and post-transcriptional control circuitry underlies much of the production and deployment of these attachment functions.
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Affiliation(s)
- Melene A Thompson
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | | | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA.
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Jiang X, Beust A, Sappa PK, Völker U, Dinse T, Herglotz J, Reinhold-Hurek B. Two Functionally Deviating Type 6 Secretion Systems Occur in the Nitrogen-Fixing Endophyte Azoarcus olearius BH72. Front Microbiol 2019; 10:459. [PMID: 30915056 PMCID: PMC6423157 DOI: 10.3389/fmicb.2019.00459] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 02/21/2019] [Indexed: 12/18/2022] Open
Abstract
Type VI protein secretion systems (T6SSs) have been identified in many plant-associated bacteria. However, despite the fact that effector proteins may modulate host responses or interbacterial competition, only a few have been functionally dissected in detail. We dissected the T6SS in Azoarcus olearius strain BH72, a nitrogen-fixing model endophyte of grasses. The genome harbors two gene clusters encoding putative T6SSs, tss-1 and tss-2, of which only T6SS-2 shared genetic organization and functional homology with the H1-T6SS of Pseudomonas aeruginosa. While tss-2 genes were constitutively expressed, tss-1 genes were strongly up-regulated under conditions of nitrogen fixation. A comparative analysis of the wild type and mutants lacking either functional tss-1 or tss-2 allowed to differentiate the functions of both secretion systems. Abundance of Hcp in the culture supernatant as an indication for T6SS activity revealed that only T6SS-2 was active, either under aerobic or nitrogen-fixing conditions. Our data show that T6SS-2 but not T6SS-1 is post-translationally regulated by phosphorylation mediated by TagE/TagG (PpkA/PppA), and by the phosphorylation-independent inhibitory protein TagF, similar to published work in Pseudomonas. Therefore, T6SS-1 appears to be post-translationally regulated by yet unknown mechanisms. Thus, both T6SS systems appear to perform different functions in Azoarcus, one of them specifically adapted to the nitrogen-fixing lifestyle.
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Affiliation(s)
- Xun Jiang
- Department of Microbe-Plant Interactions, Faculty of Biology and Chemistry, Center for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Andreas Beust
- Department of Microbe-Plant Interactions, Faculty of Biology and Chemistry, Center for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Praveen K. Sappa
- Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Uwe Völker
- Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Theresa Dinse
- Department of Microbe-Plant Interactions, Faculty of Biology and Chemistry, Center for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Julia Herglotz
- Department of Microbe-Plant Interactions, Faculty of Biology and Chemistry, Center for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Barbara Reinhold-Hurek
- Department of Microbe-Plant Interactions, Faculty of Biology and Chemistry, Center for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
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Characterization and comparative analysis of toxin-antitoxin systems in Acetobacter pasteurianus. J Ind Microbiol Biotechnol 2019; 46:869-882. [PMID: 30805740 DOI: 10.1007/s10295-019-02144-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 01/24/2019] [Indexed: 12/20/2022]
Abstract
Bacterial toxin-antitoxin (TA) systems play important roles in diverse cellular regulatory processes. Here, we characterize three putative type II TA candidates from Acetobacter pasteurianus and investigate the profile of type II TA systems in the genus Acetobacter. Based on the gene structure and activity detection, two-pairs loci were identified as the canonical hicAB and higAB TA systems, respectively, and DB34_01190-DB34_01195 as a putative new one without a canonical TA architecture. Physiologically, the expression of the three pairs conferred E. coli with additional plasmid maintenance and survival when under acetic acid stress. Chromosomal TA systems can be horizontally transferred within an ecological vinegar microbiota by co-option, and there was a tendency for toxin module loss. The antitoxin retention in the genome is suggested to have a broad role in bacterial physiology. Furthermore, A. pasteurianus strains, universally domesticated and used for industrial vinegar fermentation, showed a higher number of type II TA loci compared to the host-associated ones. The amount of TA loci per genome showed little positive relationship to insertion sequences, although its prevalence was species-associated, to the extent of even being strain-associated. The TA system is a candidate of studying the resistant mechanistic network, the TAs-dependent translatome affords a real-time profile to explore stress adaptation of A. pasteurianus, promoting industrial development.
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Agrobacterium-mediated horizontal gene transfer: Mechanism, biotechnological application, potential risk and forestalling strategy. Biotechnol Adv 2018; 37:259-270. [PMID: 30579929 DOI: 10.1016/j.biotechadv.2018.12.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 12/18/2018] [Accepted: 12/18/2018] [Indexed: 11/20/2022]
Abstract
The extraordinary capacity of Agrobacterium to transfer its genetic material to host cell makes it evolve from phytopathogen to a powerful transgenic vector. Agrobacterium-mediated stable transformation is widely used as the preferred method to create transgenic plants for molecular plant biology research and crop breeding. Recent years, both mechanism and application of Agrobacterium-mediated horizontal gene transfer have made significant progresses, especially Agrobacterium-mediated transient transformation was developed for plant biotechnology industry to produce recombinant proteins. Agrobacterium strains are almost used and saved not only by each of microbiology and molecular plant labs, but also by many of plant biotechnology manufacturers. Agrobacterium is able to transfer its genetic material to a broad range of hosts, including plant and non-plant hosts. As a consequence, the concern of environmental risk associated with the accidental release of genetically modified Agrobacterium arises. In this article, we outline the recent progress in the molecular mechanism of Agrobacterium-meditated gene transfer, focus on the application of Agrobacterium-mediated horizontal gene transfer, and review the potential risk associated with Agrobacterium-meditated gene transfer. Based on the comparison between the infecting process of Agrobacterium as a pathogen and the transgenic process of Agrobacterium as a transgenic vector, we realize that chemotaxis is the distinct difference between these two biological processes and thus discuss the possible role of chemotaxis in forestalling the potential risk of Agrobacterium-meditated horizontal gene transfer to non-target plant species.
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Wang YC, Yu M, Shih PY, Wu HY, Lai EM. Stable pH Suppresses Defense Signaling and is the Key to Enhance Agrobacterium-Mediated Transient Expression in Arabidopsis Seedlings. Sci Rep 2018; 8:17071. [PMID: 30459348 PMCID: PMC6244089 DOI: 10.1038/s41598-018-34949-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 10/29/2018] [Indexed: 01/01/2023] Open
Abstract
Agrobacterium-mediated transient expression is a powerful analysis platform for diverse plant gene functional studies, but the mechanisms regulating the expression or transformation levels are poorly studied. Previously, we developed a highly efficient and robust Agrobacterium-mediated transient expression system, named AGROBEST, for Arabidopsis seedlings. In this study, we found that AGROBEST could promote the growth of agrobacteria as well as inhibit the host immunity response. When the factor of agrobacterial growth is minimized, maintaining pH at 5.5 with MES buffer was the key to achieving optimal transient expression efficiency. The expression of plant immunity marker genes, FRK1 and NHL10, was suppressed in the pH-buffered medium as compared with non-buffered conditions in Col-0 and an efr-1 mutant lacking the immunity receptor EFR recognizing EF-Tu, a potent pathogen- or microbe-associated molecular pattern (PAMP or MAMP) of A. tumefaciens. Notably, such immune suppression could also occur in Arabidopsis seedlings without Agrobacterium infection. Furthermore, the PAMP-triggered influx of calcium ions was compromised in the pH-buffered medium. We propose that the enhanced transient expression efficiency by stable pH was due to inhibiting calcium ion uptake and subsequently led to suppressing immunity against Agrobacterium.
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Affiliation(s)
- Yi-Chieh Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Manda Yu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Po-Yuan Shih
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan
| | - Hung-Yi Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Department of Plant Pathology and Microbiology, National Taiwan University, Taipei, Taiwan
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan.
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan.
- Department of Plant Pathology and Microbiology, National Taiwan University, Taipei, Taiwan.
- Biotechnology Center, National Chung-Hsing University, Taichung, Taiwan.
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Tang G, Li Q, Xing S, Li N, Tang Z, Yu L, Yan J, Li X, Luo L. The LsrB Protein Is Required for Agrobacterium tumefaciens Interaction with Host Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:951-961. [PMID: 29547354 DOI: 10.1094/mpmi-02-18-0041-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Agrobacterium tumefaciens infects and causes crown galls in dicot plants by transferring T-DNA from the Ti plasmid to the host plant via a type IV secretion system. This process requires appropriate environmental conditions, certain plant secretions, and bacterial regulators. In our previous work, a member of the LysR family of transcriptional regulators (LsrB) in Sinorhizobium meliloti was found to modulate its symbiotic interactions with the host plant alfalfa. However, the function of its homolog in A. tumefaciens remains unclear. In this study, we show that the LsrB protein of A. tumefaciens is required for efficient transformation of host plants. A lsrB deletion mutant of A. tumefaciens exhibits a number of defects, including in succinoglycan production, attachment, and resistance to oxidative stress and iron limitation. RNA-sequencing analysis indicated that 465 genes were significantly differentially expressed (upregulation of 162 genes and downregulation of 303 genes) in the mutant, compared with the wild-type strain, including those involved in succinoglycan production, iron transporter, and detoxification enzymes for oxidative stress. Moreover, expression of the lsrB gene from S. meliloti, Brucella abortus, or A. tumefaciens rescued the defects observed in the S. meliloti or A. tumefaciens lsrB deletion mutant. Our findings suggest that a conserved mechanism of LsrB function exists in symbiotic and pathogenic bacteria of the family Rhizobiaceae.
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Affiliation(s)
- Guirong Tang
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
- 2 School of Communication & Information Engineering, Shanghai University; and
| | - Qiong Li
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Shenghui Xing
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Ningning Li
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Zheng Tang
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Liangliang Yu
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Junhui Yan
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Xuan Li
- 3 Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Li Luo
- 1 Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China
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Lin HH, Huang HM, Yu M, Lai EM, Chien HL, Liu CT. Functional Exploration of the Bacterial Type VI Secretion System in Mutualism: Azorhizobium caulinodans ORS571-Sesbania rostrata as a Research Model. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018. [PMID: 29516754 DOI: 10.1094/mpmi-01-18-0026-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The bacterial type VI secretion system (T6SS) has been considered the armed force of bacteria because it can deliver toxin effectors to prokaryotic or eukaryotic cells for survival and fitness. Although many legume symbiotic rhizobacteria encode T6SS in their genome, the biological function of T6SS in these bacteria is still unclear. To elucidate this issue, we used Azorhizobium caulinodans ORS571 and its symbiotic host Sesbania rostrata as our research model. By using T6SS gene deletion mutants, we found that T6SS provides A. caulinodans with better symbiotic competitiveness when coinfected with a T6SS-lacking strain, as demonstrated by two independent T6SS-deficient mutants. Meanwhile, the symbiotic effectiveness was not affected by T6SS because the nodule phenotype, nodule size, and nodule nitrogen-fixation ability did not differ between the T6SS mutants and the wild type when infected alone. Our data also suggest that under several lab culture conditions tested, A. caulinodans showed no T6SS-dependent interbacterial competition activity. Therefore, instead of being an antihost or antibacterial weapon of the bacterium, the T6SS in A. caulinodans ORS571 seems to participate specifically in symbiosis by increasing its symbiotic competitiveness.
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Affiliation(s)
- Hsiao-Han Lin
- 1 Institute of Biotechnology, National Taiwan University, No. 81, Chang-Xing St., Taipei 10617, Taiwan
- 2 Institute of Plant and Microbial Biology, Academia Sinica, No. 128 Section 2, Academia Rd., Nankang, Taipei 11529, Taiwan; and
| | - Hsin-Mei Huang
- 1 Institute of Biotechnology, National Taiwan University, No. 81, Chang-Xing St., Taipei 10617, Taiwan
| | - Manda Yu
- 2 Institute of Plant and Microbial Biology, Academia Sinica, No. 128 Section 2, Academia Rd., Nankang, Taipei 11529, Taiwan; and
| | - Erh-Min Lai
- 2 Institute of Plant and Microbial Biology, Academia Sinica, No. 128 Section 2, Academia Rd., Nankang, Taipei 11529, Taiwan; and
| | - Hsiao-Lin Chien
- 1 Institute of Biotechnology, National Taiwan University, No. 81, Chang-Xing St., Taipei 10617, Taiwan
| | - Chi-Te Liu
- 1 Institute of Biotechnology, National Taiwan University, No. 81, Chang-Xing St., Taipei 10617, Taiwan
- 3 Agricultural Biotechnology Research Center, Academia Sinica
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Lin JS, Pissaridou P, Wu HH, Tsai MD, Filloux A, Lai EM. TagF-mediated repression of bacterial type VI secretion systems involves a direct interaction with the cytoplasmic protein Fha. J Biol Chem 2018; 293:8829-8842. [PMID: 29599293 PMCID: PMC5995506 DOI: 10.1074/jbc.ra117.001618] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 03/09/2018] [Indexed: 01/09/2023] Open
Abstract
The bacterial type VI secretion system (T6SS) delivers effectors into eukaryotic host cells or toxins into bacterial competitor for survival and fitness. The T6SS is positively regulated by the threonine phosphorylation pathway (TPP) and negatively by the T6SS-accessory protein TagF. Here, we studied the mechanisms underlying TagF-mediated T6SS repression in two distinct bacterial pathogens, Agrobacterium tumefaciens and Pseudomonas aeruginosa. We found that in A. tumefaciens, T6SS toxin secretion and T6SS-dependent antibacterial activity are suppressed by a two-domain chimeric protein consisting of TagF and PppA, a putative phosphatase. Remarkably, this TagF domain is sufficient to post-translationally repress the T6SS, and this inhibition is independent of TPP. This repression requires interaction with a cytoplasmic protein, Fha, critical for activating T6SS assembly. In P. aeruginosa, PppA and TagF are two distinct proteins that repress T6SS in TPP-dependent and -independent pathways, respectively. P. aeruginosa TagF interacts with Fha1, suggesting that formation of this complex represents a conserved TagF-mediated regulatory mechanism. Using TagF variants with substitutions of conserved amino acid residues at predicted protein–protein interaction interfaces, we uncovered evidence that the TagF–Fha interaction is critical for TagF-mediated T6SS repression in both bacteria. TagF inhibits T6SS without affecting T6SS protein abundance in A. tumefaciens, but TagF overexpression reduces the protein levels of all analyzed T6SS components in P. aeruginosa. Our results indicate that TagF interacts with Fha, which in turn could impact different stages of T6SS assembly in different bacteria, possibly reflecting an evolutionary divergence in T6SS control.
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Affiliation(s)
- Jer-Sheng Lin
- From the Institute of Plant and Microbial Biology and
| | - Panayiota Pissaridou
- the Medical Research Council Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Hsin-Hui Wu
- the Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan and
| | - Ming-Daw Tsai
- the Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan and
| | - Alain Filloux
- the Medical Research Council Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Erh-Min Lai
- From the Institute of Plant and Microbial Biology and
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Brucella abortus Senses the Intracellular Environment through the BvrR/BvrS Two-Component System, Which Allows B. abortus To Adapt to Its Replicative Niche. Infect Immun 2018; 86:IAI.00713-17. [PMID: 29378792 DOI: 10.1128/iai.00713-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 01/16/2018] [Indexed: 02/06/2023] Open
Abstract
Brucella abortus is a facultative extracellular-intracellular pathogen belonging to a group of Alphaproteobacteria that establishes close interactions with animal cells. This bacterium enters host cells in a membrane-bound compartment, avoiding the lysosomal route and reaching the endoplasmic reticulum through the action of the type IV secretion system, VirB. In this work, we demonstrate that the BvrR/BvrS two-component system senses the intracellular environment to mount the transcriptional response required for intracellular life adaptation. By combining a method to purify intracellularly extracted bacteria with a strategy that allows direct determination of BvrR phosphorylation, we showed that upon entrance to host cells, the regulatory protein BvrR was activated (BvrR-P) by phosphorylation at aspartate 58. This activation takes place in response to intracellular cues found in early compartments, such as low pH and nutrient deprivation. Furthermore, BvrR activation was followed by an increase in the expression of VjbR and VirB. The in vitro activation of this BvrR-P/VjbR/VirB virulence circuit rescued B. abortus from the inhibition of intracellular replication induced by bafilomycin treatment of cells, demonstrating the relevance of this mechanism for intracellular bacterial survival and replication. All together, our results indicate that B. abortus senses the transition from the extracellular to the intracellular milieu through BvrR/BvrS, allowing the bacterium to transit safely to its replicative niche. These results serve as a working model for understanding the role of this family of two-component systems in the adaptation to intracellular life of Alphaproteobacteria.
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Abstract
Agrobacterium exopolysaccharides play a major role in the life of the cell. Exopolysaccharides are required for bacterial growth as a biofilm and they protect the bacteria against environmental stresses. Five of the exopolysaccharides made by A. tumefaciens have been characterized extensively with respect to their structure, synthesis, regulation, and role in the life of the bacteria. These are cyclic-β-(1, 2)-glucan, cellulose, curdlan, succinoglycan, and the unipolar polysaccharide (UPP). This chapter describes the structure, synthesis, regulation, and function of these five exopolysaccharides.
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Barton IS, Fuqua C, Platt TG. Ecological and evolutionary dynamics of a model facultative pathogen: Agrobacterium and crown gall disease of plants. Environ Microbiol 2018; 20:16-29. [PMID: 29105274 PMCID: PMC5764771 DOI: 10.1111/1462-2920.13976] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 10/20/2017] [Accepted: 10/25/2017] [Indexed: 01/09/2023]
Abstract
Many important pathogens maintain significant populations in highly disparate disease and non-disease environments. The consequences of this environmental heterogeneity in shaping the ecological and evolutionary dynamics of these facultative pathogens are incompletely understood. Agrobacterium tumefaciens, the causative agent for crown gall disease of plants has proven a productive model for many aspects of interactions between pathogens and their hosts and with other microbes. In this review, we highlight how this past work provides valuable context for the use of this system to examine how heterogeneity and transitions between disease and non-disease environments influence the ecology and evolution of facultative pathogens. We focus on several features common among facultative pathogens, such as the physiological remodelling required to colonize hosts from environmental reservoirs and the consequences of competition with host and non-host associated microbiota. In addition, we discuss how the life history of facultative pathogens likely often results in ecological tradeoffs associated with performance in disease and non-disease environments. These pathogens may therefore have different competitive dynamics in disease and non-disease environments and are subject to shifting selective pressures that can result in pathoadaptation or the within-host spread of avirulent phenotypes.
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Affiliation(s)
- Ian S. Barton
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Thomas G. Platt
- Division of Biology, Kansas State University, Manhattan, KS, USA
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Wu CF, Smith DA, Lai EM, Chang JH. The Agrobacterium Type VI Secretion System: A Contractile Nanomachine for Interbacterial Competition. Curr Top Microbiol Immunol 2018; 418:215-231. [PMID: 29992360 DOI: 10.1007/82_2018_99] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The bacterial type VI secretion system (T6SS) is a contractile nanomachine dedicated to delivering molecules out of bacterial cells. T6SS-encoding loci are in the genome sequences of many Gram-negative bacteria, and T6SS has been implicated in a plethora of roles. In the majority of cases, the T6SSs deliver effector proteins in a contact-dependent manner to antagonize other bacteria. Current models suggest that the effectors are deployed to influence social interactions in microbial communities. In this chapter, we describe the structure, function, and regulation of the T6SS and its effectors. We provide focus on the T6SS of Agrobacterium tumefaciens, the causative agent of crown gall disease, and relate the role of the T6SS to the ecology of A. tumefaciens.
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Affiliation(s)
- Chih-Feng Wu
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Delaney A Smith
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA.
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA.
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50
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Hwang HH, Yu M, Lai EM. Agrobacterium-mediated plant transformation: biology and applications. THE ARABIDOPSIS BOOK 2017; 15:e0186. [PMID: 31068763 PMCID: PMC6501860 DOI: 10.1199/tab.0186] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Plant genetic transformation heavily relies on the bacterial pathogen Agrobacterium tumefaciens as a powerful tool to deliver genes of interest into a host plant. Inside the plant nucleus, the transferred DNA is capable of integrating into the plant genome for inheritance to the next generation (i.e. stable transformation). Alternatively, the foreign DNA can transiently remain in the nucleus without integrating into the genome but still be transcribed to produce desirable gene products (i.e. transient transformation). From the discovery of A. tumefaciens to its wide application in plant biotechnology, numerous aspects of the interaction between A. tumefaciens and plants have been elucidated. This article aims to provide a comprehensive review of the biology and the applications of Agrobacterium-mediated plant transformation, which may be useful for both microbiologists and plant biologists who desire a better understanding of plant transformation, protein expression in plants, and plant-microbe interaction.
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Affiliation(s)
- Hau-Hsuan Hwang
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, 402
| | - Manda Yu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, 115
| | - Erh-Min Lai
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, 115
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