201
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Functional Characterization of EscK (Orf4), a Sorting Platform Component of the Enteropathogenic Escherichia coli Injectisome. J Bacteriol 2016; 199:JB.00538-16. [PMID: 27795324 DOI: 10.1128/jb.00538-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/03/2016] [Indexed: 02/07/2023] Open
Abstract
The type III secretion system (T3SS) is a supramolecular machine used by many bacterial pathogens to translocate effector proteins directly into the eukaryotic host cell cytoplasm. Enteropathogenic Escherichia coli (EPEC) is an important cause of infantile diarrheal disease in underdeveloped countries. EPEC virulence relies on a T3SS encoded within a chromosomal pathogenicity island known as the locus of enterocyte effacement (LEE). In this work, we pursued the functional characterization of the LEE-encoded protein EscK (previously known as Orf4). We provide evidence indicating that EscK is crucial for efficient T3S and belongs to the SctK (OrgA/YscK/MxiK) protein family, whose members have been implicated in the formation of a sorting platform for secretion of T3S substrates. Bacterial fractionation studies showed that EscK localizes to the inner membrane independently of the presence of any other T3SS component. Combining yeast two-hybrid screening and pulldown assays, we identified an interaction between EscK and the C-ring/sorting platform component EscQ. Site-directed mutagenesis of conserved residues revealed amino acids that are critical for EscK function and for its interaction with EscQ. In addition, we found that T3S substrate overproduction is capable of compensating for the absence of EscK. Overall, our data suggest that EscK is a structural component of the EPEC T3SS sorting platform, playing a central role in the recruitment of T3S substrates for boosting the efficiency of the protein translocation process. IMPORTANCE The type III secretion system (T3SS) is an essential virulence determinant for enteropathogenic Escherichia coli (EPEC) colonization of intestinal epithelial cells. Multiple EPEC effector proteins are injected via the T3SS into enterocyte cells, leading to diarrheal disease. The T3SS is encoded within a genomic pathogenicity island termed the locus of enterocyte effacement (LEE). Here we unravel the function of EscK, a previously uncharacterized LEE-encoded protein. We show that EscK is central for T3SS biogenesis and function. EscK forms a protein complex with EscQ, the main component of the cytoplasmic sorting platform, serving as a docking site for T3S substrates. Our results provide a comprehensive functional analysis of an understudied component of T3SSs.
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202
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Liu J, Lu SY, Orfe LH, Ren CH, Hu CQ, Call DR, Avillan JJ, Zhao Z. ExsE Is a Negative Regulator for T3SS Gene Expression in Vibrio alginolyticus. Front Cell Infect Microbiol 2016; 6:177. [PMID: 27999769 PMCID: PMC5138213 DOI: 10.3389/fcimb.2016.00177] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 11/22/2016] [Indexed: 12/13/2022] Open
Abstract
Type III secretion systems (T3SSs) contribute to microbial pathogenesis of Vibrio species, but the regulatory mechanisms are complex. We determined if the classic ExsACDE protein-protein regulatory model from Pseudomonas aeruginosa applies to Vibrio alginolyticus. Deletion mutants in V. alginolyticus demonstrated that, as expected, the T3SS is positively regulated by ExsA and ExsC and negatively regulated by ExsD and ExsE. Interestingly, deletion of exsE enhanced the ability of V. alginolyticus to induce host-cell death while cytotoxicity was inhibited by in trans complementation of this gene in a wild-type strain, a result that differs from a similar experiment with Vibrio parahaemolyticus ExsE. We further showed that ExsE is a secreted protein that does not contribute to adhesion to Fathead minnow epithelial cells. An in vitro co-immunoprecipitation assay confirmed that ExsE binds to ExsC to exert negative regulatory effect on T3SS genes. T3SS in V. alginolyticus can be activated in the absence of physical contact with host cells and a separate regulatory pathway appears to contribute to the regulation of ExsA. Consequently, like ExsE from P. aeruginosa, ExsE is a negative regulator for T3SS gene expression in V. alginolyticus. Unlike the V. parahaemolyticus orthologue, however, deletion of exsE from V. alginolyticus enhanced in vitro cytotoxicity.
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Affiliation(s)
- Jinxin Liu
- Institute of Marine Biology, College of Oceanography, Hohai UniversityNanjing, China; Paul G. Allen School for Global Animal Health, Washington State UniversityPullman, WA, USA
| | - Shao-Yeh Lu
- Paul G. Allen School for Global Animal Health, Washington State University Pullman, WA, USA
| | - Lisa H Orfe
- Paul G. Allen School for Global Animal Health, Washington State University Pullman, WA, USA
| | - Chun-Hua Ren
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences Guangzhou, China
| | - Chao-Qun Hu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences Guangzhou, China
| | - Douglas R Call
- Paul G. Allen School for Global Animal Health, Washington State University Pullman, WA, USA
| | - Johannetsy J Avillan
- Paul G. Allen School for Global Animal Health, Washington State University Pullman, WA, USA
| | - Zhe Zhao
- Institute of Marine Biology, College of Oceanography, Hohai UniversityNanjing, China; Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of SciencesGuangzhou, China
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203
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A Method for Characterizing the Type III Secretion System's Contribution to Pathogenesis: Homologous Recombination to Generate Yersinia pestis Type III Secretion System Mutants. Methods Mol Biol 2016. [PMID: 27837489 DOI: 10.1007/978-1-4939-6649-3_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The type III (T3S) secretion system of many gram-negative bacteria is a surface-exposed protein secretion apparatus used to directly inject bacterial effector molecules into eukaryotic cells. These effector molecules contribute to bacterial pathogenesis in many ways, and have been shown to be crucial for infectivity. Here, we describe a protocol for using homologous recombination to generate T3S system mutants to assess the role of different T3S system proteins in bacterial pathogenesis.
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204
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Alvine TD, Bradley DS, Nilles ML. Mouse Immunization with Purified Needle Proteins from Type III Secretion Systems and the Characterization of the Immune Response to These Proteins. Methods Mol Biol 2016; 1531:193-201. [PMID: 27837493 DOI: 10.1007/978-1-4939-6649-3_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Many Gram-negative pathogens utilize a type III secretion (T3S) system to directly deliver effector molecules into host eukaryotic cells to manipulate cellular processes. These surface-exposed syringe-like structures are highly conserved, necessary for pathogenesis, and hence are therapeutic targets against a number of Gram-negative pathogens. Here we describe a protocol for using purified needle proteins to immunize mice, and subsequently, ways to characterize the immune response to immunization.
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Affiliation(s)
- Travis D Alvine
- Department of Biomedical Sciences, University of North Dakota, 1301 Columbia Road North, Stop 9037, Grand Forks, ND, 58202, USA
| | - David S Bradley
- Department of Biomedical Sciences, University of North Dakota, 1301 Columbia Road North, Stop 9037, Grand Forks, ND, 58202, USA.
| | - Matthew L Nilles
- Department of Biomedical Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND, USA
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205
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Isolation of Type III Secretion System Needle Complexes by Shearing. Methods Mol Biol 2016. [PMID: 27837481 DOI: 10.1007/978-1-4939-6649-3_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Type III secretion (T3S) needle proteins are essential for the pathogenesis of many gram-negative bacteria. The needle component of the T3S system serves as the conduit for the translocation of effector proteins from the cytoplasm of many gram-negative bacteria into their target eukaryotic cells. Despite substantial advances that have been made in their characterization, a lot is still unknown about their interactions with other T3S system proteins and their roles in modulating host immune responses during infections. Critical to achieving this knowledge is the ability to isolate these needle proteins in their stable, native form. In this chapter, we describe a modified, streamlined isolation strategy for native forms of these T3S system needle proteins. We also present assays to detect the presence and quantification of these needle proteins.
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206
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Arrieumerlou C. [Cell biology applications for a type III secretion-based protein delivery tool]. Med Sci (Paris) 2016; 32:797-799. [PMID: 27758733 DOI: 10.1051/medsci/20163210002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Cécile Arrieumerlou
- Inserm U1016, Institut Cochin ; CNRS, UMR8104 ; université Paris Descartes, Sorbonne Paris Cité, 22, rue Méchain 75014 Paris, France
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207
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Gaytán MO, Martínez-Santos VI, Soto E, González-Pedrajo B. Type Three Secretion System in Attaching and Effacing Pathogens. Front Cell Infect Microbiol 2016; 6:129. [PMID: 27818950 PMCID: PMC5073101 DOI: 10.3389/fcimb.2016.00129] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/27/2016] [Indexed: 02/06/2023] Open
Abstract
Enteropathogenic Escherichia coli and enterohemorrhagic E. coli are diarrheagenic bacterial human pathogens that cause severe gastroenteritis. These enteric pathotypes, together with the mouse pathogen Citrobacter rodentium, belong to the family of attaching and effacing pathogens that form a distinctive histological lesion in the intestinal epithelium. The virulence of these bacteria depends on a type III secretion system (T3SS), which mediates the translocation of effector proteins from the bacterial cytosol into the infected cells. The core architecture of the T3SS consists of a multi-ring basal body embedded in the bacterial membranes, a periplasmic inner rod, a transmembrane export apparatus in the inner membrane, and cytosolic components including an ATPase complex and the C-ring. In addition, two distinct hollow appendages are assembled on the extracellular face of the basal body creating a channel for protein secretion: an approximately 23 nm needle, and a filament that extends up to 600 nm. This filamentous structure allows these pathogens to get through the host cells mucus barrier. Upon contact with the target cell, a translocation pore is assembled in the host membrane through which the effector proteins are injected. Assembly of the T3SS is strictly regulated to ensure proper timing of substrate secretion. The different type III substrates coexist in the bacterial cytoplasm, and their hierarchical secretion is determined by specialized chaperones in coordination with two molecular switches and the so-called sorting platform. In this review, we present recent advances in the understanding of the T3SS in attaching and effacing pathogens.
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Affiliation(s)
- Meztlli O Gaytán
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Verónica I Martínez-Santos
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Eduardo Soto
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Bertha González-Pedrajo
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
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208
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Daniel C, Titecat M, Poiret S, Cayet D, Boutillier D, Simonet M, Sirard JC, Lemaître N, Sebbane F. Characterization of the protective immune response to Yersinia pseudotuberculosis infection in mice vaccinated with an LcrV-secreting strain of Lactococcus lactis. Vaccine 2016; 34:5762-5767. [PMID: 27742220 DOI: 10.1016/j.vaccine.2016.09.060] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 09/29/2016] [Accepted: 09/30/2016] [Indexed: 01/03/2023]
Abstract
BACKGROUND Pseudotuberculosis is an infection caused by the bacterial enteropathogen Yersinia pseudotuberculosis and is considered to be a significant problem in veterinary medicine. We previously found that intranasal administration of a recombinant Lactococcus lactis strain that secretes the low-calcium response V (LcrV) antigen from Y. pseudotuberculosis (Ll-LcrV) confers protection against a lethal Y. pseudotuberculosis infection. Here, we aimed at characterizing the immunological basis of this LcrV-elicited protective response and at determining the duration of vaccine-induced immunity. METHODS Splenocytes from BALB/c mice intranasally immunized with Ll-LcrV or Ll as control were immunostained then analyzed by flow cytometry. Protection against a lethal intravenous injection of Y. pseudotuberculosis was also determined (i) in immunized BALB/c mice depleted or not of CD4+, CD8+ or CD25+ cells and (ii) in naïve BALB/c mice receiving serum from immunized mice by counting the number of bacteria in liver and spleen. Lastly, survival rate of immunized BALB/c mice following a lethal intravenous injection of Y. pseudotuberculosis was followed up to 9-months. RESULTS We found that T and B lymphocytes but not non-conventional lymphoid cells were affected by Ll-LcrV immunization. We also observed that depletion of CD4+ and CD25+ but not CD8+ cells in immunized mice eradicated protection against a lethal systemic Y. pseudotuberculosis infection, suggesting that activated CD4+ T lymphocytes are required for vaccine-induced protection. Adoptive transfer of LcrV-specific antibodies from Ll-LcrV-immunized animals significantly reduced the bacterial counts in the liver compared to non-vaccinated mice. Lastly, the protective immunity conferred by Ll-LcrV decreased slightly over time; nevertheless almost 60% of the mice survived a lethal bacterial challenge at 9months post-vaccination. CONCLUSION Mucosal vaccination of mice with Ll-LcrV induced cell- and antibody-mediated protective immunity against Y. pseudotuberculosis infection in the mouse and the protection is long-lasting.
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Affiliation(s)
- Catherine Daniel
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Marie Titecat
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Sabine Poiret
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Delphine Cayet
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Denise Boutillier
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Michel Simonet
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Jean-Claude Sirard
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Nadine Lemaître
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Florent Sebbane
- Univ. Lille, Inserm, CNRS, CHU Lille, Institut Pasteur de Lille, U1019 - UMR 8204 - CIIL - Center for Infection and Immunity of Lille, F-59000 Lille, France.
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209
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Goldberg T, Rost B, Bromberg Y. Computational prediction shines light on type III secretion origins. Sci Rep 2016; 6:34516. [PMID: 27713481 PMCID: PMC5054392 DOI: 10.1038/srep34516] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 09/15/2016] [Indexed: 01/27/2023] Open
Abstract
Type III secretion system is a key bacterial symbiosis and pathogenicity mechanism responsible for a variety of infectious diseases, ranging from food-borne illnesses to the bubonic plague. In many Gram-negative bacteria, the type III secretion system transports effector proteins into host cells, converting resources to bacterial advantage. Here we introduce a computational method that identifies type III effectors by combining homology-based inference with de novo predictions, reaching up to 3-fold higher performance than existing tools. Our work reveals that signals for recognition and transport of effectors are distributed over the entire protein sequence instead of being confined to the N-terminus, as was previously thought. Our scan of hundreds of prokaryotic genomes identified previously unknown effectors, suggesting that type III secretion may have evolved prior to the archaea/bacteria split. Crucially, our method performs well for short sequence fragments, facilitating evaluation of microbial communities and rapid identification of bacterial pathogenicity – no genome assembly required. pEffect and its data sets are available at http://services.bromberglab.org/peffect.
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Affiliation(s)
- Tatyana Goldberg
- Department of Informatics, Bioinformatics &Computational Biology - I12, TUM, Garching, Germany.,Graduate School, Center of Doctoral Studies in Informatics and its Applications (CeDoSIA), TUM, Garching, Germany
| | - Burkhard Rost
- Department of Informatics, Bioinformatics &Computational Biology - I12, TUM, Garching, Germany.,Institute for Advanced Study (TUM-IAS), Garching, Germany.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Yana Bromberg
- Institute for Advanced Study (TUM-IAS), Garching, Germany.,Department of Biochemistry and Microbiology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ, USA
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210
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Suriyanarayanan T, Periasamy S, Lin MH, Ishihama Y, Swarup S. Flagellin FliC Phosphorylation Affects Type 2 Protease Secretion and Biofilm Dispersal in Pseudomonas aeruginosa PAO1. PLoS One 2016; 11:e0164155. [PMID: 27701473 PMCID: PMC5049796 DOI: 10.1371/journal.pone.0164155] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/20/2016] [Indexed: 12/02/2022] Open
Abstract
Protein phosphorylation has a major role in controlling the life-cycle and infection stages of bacteria. Proteome-wide occurrence of S/T/Y phosphorylation has been reported for many prokaryotic systems. Previously, we reported the phosphoproteome of Pseudomonas aeruginosa and Pseudomonas putida. In this study, we show the role of S/T phosphorylation of one motility protein, FliC, in regulating multiple surface-associated phenomena of P. aeruginosa PAO1. This is the first report of occurrence of phosphorylation in the flagellar protein, flagellin FliC in its highly conserved N-terminal NDO domain across several Gram negative bacteria. This phosphorylation is likely a well-regulated phenomenon as it is growth phase dependent in planktonic cells. The absence of phosphorylation in the conserved T27 and S28 residues of FliC, interestingly, did not affect swimming motility, but affected the secretome of type 2 secretion system (T2SS) and biofilm formation of PAO1. FliC phosphomutants had increased levels and activities of type 2 secretome proteins. The secretion efficiency of T2SS machinery is associated with flagellin phosphorylation. FliC phosphomutants also formed reduced biofilms at 24 h under static conditions and had delayed biofilm dispersal under dynamic flow conditions, respectively. The levels of type 2 secretome and biofilm formation under static conditions had an inverse correlation. Hence, increase in type 2 secretome levels was accompanied by reduced biofilm formation in the FliC phosphomutants. As T2SS is involved in nutrient acquisition and biofilm dispersal during survival and spread of P. aeruginosa, we propose that FliC phosphorylation has a role in ecological adaptation of this opportunistic environmental pathogen. Altogether, we found a system of phosphorylation that affects key surface related processes such as proteases secretion by T2SS, biofilm formation and dispersal.
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Affiliation(s)
- Tanujaa Suriyanarayanan
- Metabolites Biology Lab, Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- Microbiology Lab, Faculty of Dentistry, National University of Singapore, Singapore, Sinagpore
| | - Saravanan Periasamy
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore, Singapore
- Rajalakshmi Engineering College, Chennai, Tamil Nadu, India
| | - Miao-Hsia Lin
- Department of Molecular and Cellular Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Yasushi Ishihama
- Department of Molecular and Cellular Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Sanjay Swarup
- Metabolites Biology Lab, Department of Biological Sciences, National University of Singapore, Singapore, Singapore
- NUS Environmental Research Institute (NERI), National University of Singapore, Singapore, Singapore
- Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore, Singapore
- Synthetic Biology for Clinical and Technological Innovation (SynCTI), Centre for Life Sciences, National University of Singapore, Singapore, Singapore
- * E-mail:
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211
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Lin IT, Chiou YM, Liang YC, Lin CN, Sun WSW, Li S, Chang CH, Syu WJ, Chen JW. Unique clustering genes in the bacterial chromosome affecting the type-III secretion of enterohaemorrhagic Escherichia coli. Microbiology (Reading) 2016; 162:1744-1754. [DOI: 10.1099/mic.0.000348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Affiliation(s)
- I-Ting Lin
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Yi-Ming Chiou
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Yen-Chia Liang
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Ching-Nan Lin
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Wei-Sheng W. Sun
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Shiaowen Li
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Chuan-Hsiung Chang
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Wan-Jr Syu
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Jenn-Wei Chen
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, ROC
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212
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Transcriptomic and Phenotypic Analysis Reveals New Functions for the Tat Pathway in Yersinia pseudotuberculosis. J Bacteriol 2016; 198:2876-86. [PMID: 27501981 DOI: 10.1128/jb.00352-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 07/28/2016] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED The twin-arginine translocation (Tat) system mediates the secretion of folded proteins that are identified via an N-terminal signal peptide in bacteria, plants, and archaea. Tat systems are associated with virulence in many bacterial pathogens, and our previous studies revealed that Tat-deficient Yersinia pseudotuberculosis was severely attenuated for virulence. Aiming to identify Tat-dependent pathways and phenotypes of relevance for in vivo infection, we analyzed the global transcriptome of parental and ΔtatC mutant strains of Y. pseudotuberculosis during exponential and stationary growth at 26°C and 37°C. The most significant changes in the transcriptome of the ΔtatC mutant were seen at 26°C during stationary-phase growth, and these included the altered expression of genes related to virulence, stress responses, and metabolism. Subsequent phenotypic analysis based on these transcriptome changes revealed several novel Tat-dependent phenotypes, including decreased YadA expression, impaired growth under iron-limited and high-copper conditions, as well as acidic pH and SDS. Several functionally related Tat substrates were also verified to contribute to these phenotypes. Interestingly, the phenotypic defects observed in the Tat-deficient strain were generally more pronounced than those in mutants lacking the Tat substrate predicted to contribute to that specific function. Altogether, this provides new insight into the impact of Tat deficiency on in vivo fitness and survival/replication of Y. pseudotuberculosis during infection. IMPORTANCE In addition to its established role in mediating the secretion of housekeeping enzymes, the Tat system has been recognized as being involved in infection. In some clinically relevant bacteria, such as Pseudomonas spp., several key virulence determinants can readily be identified among the Tat substrates. In enteropathogens, such as Yersinia spp., there are no obvious virulence determinants among the Tat substrates. Tat mutants show no growth defect in vitro but are highly attenuated in in vivo This makes Tat an attractive target for the development of novel antimicrobials. Therefore, it is important to establish the causes of the attenuation. Here, we show that the attenuation is likely due to synergistic effects of different Tat-dependent phenotypes that each contributes to lowered in vivo fitness.
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213
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Pakharukova N, Roy S, Tuittila M, Rahman MM, Paavilainen S, Ingars AK, Skaldin M, Lamminmäki U, Härd T, Teneberg S, Zavialov AV. Structural basis for Myf and Psa fimbriae-mediated tropism of pathogenic strains of Yersinia for host tissues. Mol Microbiol 2016; 102:593-610. [PMID: 27507539 DOI: 10.1111/mmi.13481] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2016] [Indexed: 02/06/2023]
Abstract
Three pathogenic species of the genus Yersinia assemble adhesive fimbriae via the FGL-chaperone/usher pathway. Closely related Y. pestis and Y. pseudotuberculosis elaborate the pH6 antigen (Psa), which mediates bacterial attachment to alveolar cells of the lung. Y. enterocolitica, instead, assembles the homologous fimbriae Myf of unknown function. Here, we discovered that Myf, like Psa, specifically recognizes β1-3- or β1-4-linked galactose in glycosphingolipids, but completely lacks affinity for phosphatidylcholine, the main receptor for Psa in alveolar cells. The crystal structure of a subunit of Psa (PsaA) complexed with choline together with mutagenesis experiments revealed that PsaA has four phosphatidylcholine binding pockets that enable super-high-avidity binding of Psa-fibres to cell membranes. The pockets are arranged as six tyrosine residues, which are all missing in the MyfA subunit of Myf. Conversely, the crystal structure of the MyfA-galactose complex revealed that the galactose-binding site is more extended in MyfA, enabling tighter binding to lactosyl moieties. Our results suggest that during evolution, Psa has acquired a tyrosine-rich surface that enables it to bind to phosphatidylcholine and mediate adhesion of Y. pestis/pseudotuberculosis to alveolar cells, whereas Myf has specialized as a carbohydrate-binding adhesin, facilitating the attachment of Y. enterocolitica to intestinal cells.
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Affiliation(s)
- Natalia Pakharukova
- Department of Chemistry, University of Turku, Turku, Joint Biotechnology Laboratory, Arcanum, Vatselankatu 2, Turku, 20500, Finland
| | - Saumendra Roy
- Department of Chemistry, University of Turku, Turku, Joint Biotechnology Laboratory, Arcanum, Vatselankatu 2, Turku, 20500, Finland.,Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCentre, P.O. BOX 7016, Uppsala, 75007, Sweden
| | - Minna Tuittila
- Department of Chemistry, University of Turku, Turku, Joint Biotechnology Laboratory, Arcanum, Vatselankatu 2, Turku, 20500, Finland
| | - Mohammad M Rahman
- Department of Chemistry, University of Turku, Turku, Joint Biotechnology Laboratory, Arcanum, Vatselankatu 2, Turku, 20500, Finland
| | - Sari Paavilainen
- Department of Chemistry, University of Turku, Turku, Joint Biotechnology Laboratory, Arcanum, Vatselankatu 2, Turku, 20500, Finland
| | - Anna-Karin Ingars
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, P.O. BOX 440, Göteborg, 40530, Sweden
| | - Maksym Skaldin
- Department of Chemistry, University of Turku, Turku, Joint Biotechnology Laboratory, Arcanum, Vatselankatu 2, Turku, 20500, Finland.,Department of Biochemistry/Biotechnology, University of Turku, Tykistökatu 6A, Turku, 20014, Finland
| | - Urpo Lamminmäki
- Department of Biochemistry/Biotechnology, University of Turku, Tykistökatu 6A, Turku, 20014, Finland
| | - Torleif Härd
- Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCentre, P.O. BOX 7016, Uppsala, 75007, Sweden
| | - Susann Teneberg
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, P.O. BOX 440, Göteborg, 40530, Sweden
| | - Anton V Zavialov
- Department of Chemistry, University of Turku, Turku, Joint Biotechnology Laboratory, Arcanum, Vatselankatu 2, Turku, 20500, Finland.,Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCentre, P.O. BOX 7016, Uppsala, 75007, Sweden
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214
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Rüter C, Schmidt MA. Cell-Penetrating Bacterial Effector Proteins: Better Tools than Targets. Trends Biotechnol 2016; 35:109-120. [PMID: 27592802 DOI: 10.1016/j.tibtech.2016.08.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 08/01/2016] [Accepted: 08/04/2016] [Indexed: 12/20/2022]
Abstract
Bacterial pathogens have developed intriguing virulence mechanisms, including several sophisticated nanomachines, for injecting effector proteins to manipulate host immune signaling pathways for their own benefit. Therefore, bacterial genomes harbor a wealth of information about how to manipulate the defense systems of the host. Current understanding addresses virulence mechanisms mostly as targets for antimicrobials. We propose a change of paradigm by exploiting bacterial effectors not as targets but as tools for the directed manipulation of host signaling - for the benefit of the host. Recently, effector proteins have been identified that autonomously translocate into host cells, representing a novel class of cell-penetrating peptides (CPPs) or effectors (CPEs). Moreover, autonomous cell penetration overcomes a major hurdle in pharmacology by transducing specific therapeutic agents to intracellular targets.
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Affiliation(s)
- Christian Rüter
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), Westfälische Wilhelms-Universität Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany.
| | - M Alexander Schmidt
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), Westfälische Wilhelms-Universität Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany.
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215
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Huang YC, Lin YC, Wei CF, Deng WL, Huang HC. The pathogenicity factor HrpF interacts with HrpA and HrpG to modulate type III secretion system (T3SS) function and t3ss expression in Pseudomonas syringae pv. averrhoi. MOLECULAR PLANT PATHOLOGY 2016; 17:1080-94. [PMID: 26638129 PMCID: PMC6638529 DOI: 10.1111/mpp.12349] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 11/05/2015] [Accepted: 11/29/2015] [Indexed: 05/08/2023]
Abstract
To ensure the optimal infectivity on contact with host cells, pathogenic Pseudomonas syringae has evolved a complex mechanism to control the expression and construction of the functional type III secretion system (T3SS) that serves as a dominant pathogenicity factor. In this study, we showed that the hrpF gene of P. syringae pv. averrhoi, which is located upstream of hrpG, encodes a T3SS-dependent secreted/translocated protein. Mutation of hrpF leads to the loss of bacterial ability on elicitation of disease symptoms in the host and a hypersensitive response in non-host plants, and the secretion or translocation of the tested T3SS substrates into the bacterial milieu or plant cells. Moreover, overexpression of hrpF in the wild-type results in delayed HR and reduced t3ss expression. The results of protein-protein interactions demonstrate that HrpF interacts directly with HrpG and HrpA in vitro and in vivo, and protein stability assays reveal that HrpF assists HrpA stability in the bacterial cytoplasm, which is reduced by a single amino acid substitution at the 67th lysine residue of HrpF with alanine. Taken together, the data presented here suggest that HrpF has two roles in the assembly of a functional T3SS: one by acting as a negative regulator, possibly involved in the HrpSVG regulation circuit via binding to HrpG, and the other by stabilizing HrpA in the bacterial cytoplasm via HrpF-HrpA interaction prior to the secretion and formation of Hrp pilus on the bacterial surface.
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Affiliation(s)
- Yi-Chiao Huang
- Department of Plant Pathology, National Chung Hsing University, Taichung, 40227, Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Yuan-Chuen Lin
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Chia-Fong Wei
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Wen-Ling Deng
- Department of Plant Pathology, National Chung Hsing University, Taichung, 40227, Taiwan
- Agricultural Biotechnology Center, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Hsiou-Chen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
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216
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Depluverez S, Devos S, Devreese B. The Role of Bacterial Secretion Systems in the Virulence of Gram-Negative Airway Pathogens Associated with Cystic Fibrosis. Front Microbiol 2016; 7:1336. [PMID: 27625638 PMCID: PMC5003817 DOI: 10.3389/fmicb.2016.01336] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 08/12/2016] [Indexed: 11/16/2022] Open
Abstract
Cystic fibrosis (CF) is the most common lethal inherited disorder in Caucasians. It is caused by mutation of the CF transmembrane conductance regulator (CFTR) gene. A defect in the CFTR ion channel causes a dramatic change in the composition of the airway surface fluid, leading to a highly viscous mucus layer. In healthy individuals, the majority of bacteria trapped in the mucus layer are removed and destroyed by mucociliary clearance. However, in the lungs of patients with CF, the mucociliary clearance is impaired due to dehydration of the airway surface fluid. As a consequence, patients with CF are highly susceptible to chronic or intermittent pulmonary infections, often causing extensive lung inflammation and damage, accompanied by a decreased life expectancy. This mini review will focus on the different secretion mechanisms used by the major bacterial CF pathogens to release virulence factors, their role in resistance and discusses the potential for therapeutically targeting secretion systems.
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Affiliation(s)
- Sofie Depluverez
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University Ghent, Belgium
| | - Simon Devos
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University Ghent, Belgium
| | - Bart Devreese
- Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University Ghent, Belgium
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217
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Chung LK, Park YH, Zheng Y, Brodsky IE, Hearing P, Kastner DL, Chae JJ, Bliska JB. The Yersinia Virulence Factor YopM Hijacks Host Kinases to Inhibit Type III Effector-Triggered Activation of the Pyrin Inflammasome. Cell Host Microbe 2016; 20:296-306. [PMID: 27569559 DOI: 10.1016/j.chom.2016.07.018] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 06/29/2016] [Accepted: 07/22/2016] [Indexed: 02/07/2023]
Abstract
Pathogenic Yersinia, including Y. pestis, the agent of plague in humans, and Y. pseudotuberculosis, the related enteric pathogen, deliver virulence effectors into host cells via a prototypical type III secretion system to promote pathogenesis. These effectors, termed Yersinia outer proteins (Yops), modulate multiple host signaling responses. Studies in Y. pestis and Y. pseudotuberculosis have shown that YopM suppresses infection-induced inflammasome activation; however, the underlying molecular mechanism is largely unknown. Here we show that YopM specifically restricts the pyrin inflammasome, which is triggered by the RhoA-inactivating enzymatic activities of YopE and YopT, in Y. pseudotuberculosis-infected macrophages. The attenuation of a yopM mutant is fully reversed in pyrin knockout mice, demonstrating that YopM inhibits pyrin to promote virulence. Mechanistically, YopM recruits and activates the host kinases PRK1 and PRK2 to negatively regulate pyrin by phosphorylation. These results show how a virulence factor can hijack host kinases to inhibit effector-triggered pyrin inflammasome activation.
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Affiliation(s)
- Lawton K Chung
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Center for Infectious Diseases, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Yong Hwan Park
- Inflammatory Disease Section, Metabolic, Cardiovascular, and Inflammatory Disease Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - Yueting Zheng
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Igor E Brodsky
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Patrick Hearing
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA
| | - Daniel L Kastner
- Inflammatory Disease Section, Metabolic, Cardiovascular, and Inflammatory Disease Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - Jae Jin Chae
- Inflammatory Disease Section, Metabolic, Cardiovascular, and Inflammatory Disease Genomics Branch, National Human Genome Research Institute, NIH, Bethesda, MD 20892, USA
| | - James B Bliska
- Department of Molecular Genetics and Microbiology, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA; Center for Infectious Diseases, School of Medicine, Stony Brook University, Stony Brook, NY 11794, USA.
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218
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Tobias NJ, Mishra B, Gupta DK, Sharma R, Thines M, Stinear TP, Bode HB. Genome comparisons provide insights into the role of secondary metabolites in the pathogenic phase of the Photorhabdus life cycle. BMC Genomics 2016; 17:537. [PMID: 27488257 PMCID: PMC4971723 DOI: 10.1186/s12864-016-2862-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 06/29/2016] [Indexed: 01/28/2023] Open
Abstract
Background Bacteria within the genus Photorhabdus maintain mutualistic symbioses with nematodes in complicated lifecycles that also involves insect pathogenic phases. Intriguingly, these bacteria are rich in biosynthetic gene clusters that produce compounds with diverse biological activities. As a basis to better understand the life cycles of Photorhabdus we sequenced the genomes of two recently discovered representative species and performed detailed genomic comparisons with five publically available genomes. Results Here we report the genomic details of two new reference Photorhabdus species. By then conducting genomic comparisons across the genus, we show that there are several highly conserved biosynthetic gene clusters. These clusters produce a range of bioactive small molecules that support the pathogenic phase of the integral relationship that Photorhabdus maintain with nematodes. Conclusions Photorhabdus contain several genetic loci that allow them to become specialist insect pathogens by efficiently evading insect immune responses and killing the insect host. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2862-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nicholas J Tobias
- Fachbereich Biowissenschaften, Merck Stiftungsprofessur für Molekulare Biotechnologie, Goethe Universität Frankfurt, Frankfurt am Main, Germany
| | - Bagdevi Mishra
- Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, 60325, Frankfurt am Main, Germany.,Fachbereich Biowissenschaften, Institut für Ökologie, Evolution und Diversität, Goethe Universität Frankfurt, Max-von-Laue-Str. 13, 60438, Frankfurt am Main, Germany
| | - Deepak K Gupta
- Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, 60325, Frankfurt am Main, Germany.,Fachbereich Biowissenschaften, Institut für Ökologie, Evolution und Diversität, Goethe Universität Frankfurt, Max-von-Laue-Str. 13, 60438, Frankfurt am Main, Germany
| | - Rahul Sharma
- Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, 60325, Frankfurt am Main, Germany
| | - Marco Thines
- Biodiversity and Climate Research Centre (BiK-F), Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, 60325, Frankfurt am Main, Germany.,Fachbereich Biowissenschaften, Institut für Ökologie, Evolution und Diversität, Goethe Universität Frankfurt, Max-von-Laue-Str. 13, 60438, Frankfurt am Main, Germany
| | - Timothy P Stinear
- Department of Microbiology and Immunology, University of Melbourne, at the Doherty Institute for Infection and Immunity, Parkville, VIC, 3010, Australia
| | - Helge B Bode
- Fachbereich Biowissenschaften, Merck Stiftungsprofessur für Molekulare Biotechnologie, Goethe Universität Frankfurt, Frankfurt am Main, Germany. .,Buchmann Institute for Molecular Life Sciences (BMLS), Goethe Universität Frankfurt, Frankfurt am Main, Germany.
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219
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Furukawa Y, Inoue Y, Sakaguchi A, Mori Y, Fukumura T, Miyata T, Namba K, Minamino T. Structural stability of flagellin subunit affects the rate of flagellin export in the absence of FliS chaperone. Mol Microbiol 2016; 102:405-416. [PMID: 27461872 DOI: 10.1111/mmi.13469] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2016] [Indexed: 12/17/2022]
Abstract
FliS chaperone binds to flagellin FliC in the cytoplasm and transfers FliC to a sorting platform of the flagellar type III export apparatus through the interaction between FliS and FlhA for rapid and efficient protein export during flagellar filament assembly. FliS also suppresses the secretion of an anti-σ factor, FlgM. Loss of FliS results in a short filament phenotype although the expression levels of FliC are increased considerably due to an increase in the secretion level of FlgM. Here to clarify the rate limiting step of FliC export in the absence of FliS, we isolated bypass mutants from a Salmonella ΔfliS mutant. All the bypass mutations were identified in FliC. These bypass mutations increased the export rate of FliC by ca. twofold, allowing the bypass mutant cells to produce longer filaments than the parental ΔfliS cells. Both far-UV CD measurements and limited proteolysis revealed that the bypass mutations significantly destabilize the folded structure of FliC monomer. These results suggest that an unfolding step of FliC limits the export rate of FliC in the ΔfliS mutant, thereby producing short filaments. We propose that FliS promotes FliC docking at the FlhA platform to facilitate subsequent unfolding of FliC.
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Affiliation(s)
- Yukio Furukawa
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yumi Inoue
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Aya Sakaguchi
- Department of Food Science and Nutrition, Faculty of Human Life and Science, Doshisha Women's College of Liberal Arts, Kyoto, 602-0893, Japan
| | - Yoko Mori
- Department of Food Science and Nutrition, Faculty of Human Life and Science, Doshisha Women's College of Liberal Arts, Kyoto, 602-0893, Japan
| | - Takuma Fukumura
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Tomoko Miyata
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Quantitative Biology Center, RIKEN, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan. .,Quantitative Biology Center, RIKEN, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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220
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Strayer AL, Jeyaprakash A, Minsavage GV, Timilsina S, Vallad GE, Jones JB, Paret ML. A Multiplex Real-Time PCR Assay Differentiates Four Xanthomonas Species Associated with Bacterial Spot of Tomato. PLANT DISEASE 2016; 100:1660-1668. [PMID: 30686244 DOI: 10.1094/pdis-09-15-1085-re] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Bacterial spot of tomato, a major problem in many tomato production areas, is caused by Xanthomonas euvesicatoria, X. vesicatoria, X. perforans, and X. gardneri. In order to detect and identify the bacterial spot pathogens, we evaluated a region of hrpB operon as a source for primers and probes for real-time polymerase chain reaction (PCR). A 420-bp fragment of the hrpB7 gene was amplified by PCR from 75 strains representing the four species. The PCR products were sequenced and phylogenetic analysis revealed that hrpB7 is highly conserved within each species, with a single-nucleotide polymorphism (SNP) among the X. vesicatoria strains. X. euvesicatoria and X. perforans varied by two SNP. Four probes and two primer sets were designed to target the four bacterial spot pathogens based on their hrpB7 gene sequences. In order to simultaneously detect the four bacterial spot pathogens, the four probes and two primer sets were optimized for a multiplex real-time TaqMan PCR assay. The optimized multiplex assay was determined to be highly specific to the four bacterial spot pathogens. Because the optimized multiplex assay facilitated the identification of each bacterial spot pathogen from pure cultures and infected plant tissue, it holds great potential as a diagnostic tool.
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Affiliation(s)
- A L Strayer
- Department of Plant Pathology, University of Florida, Gainesville 32611
| | - A Jeyaprakash
- Division of Plant Industry, Florida Department of Agriculture and Consumer Services, Gainesville 32608
| | - G V Minsavage
- Department of Plant Pathology, University of Florida, Gainesville
| | - S Timilsina
- Department of Plant Pathology, University of Florida, Gainesville
| | - G E Vallad
- Department of Plant Pathology, Gulf Coast Research and Education Center, University of Florida, Wimauma 33598
| | - J B Jones
- Department of Plant Pathology, University of Florida, Gainesville
| | - M L Paret
- Department of Plant Pathology, North Florida Research and Education Center, University of Florida, Quincy 32351
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221
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Monteiro R, Ageorges V, Rojas-Lopez M, Schmidt H, Weiss A, Bertin Y, Forano E, Jubelin G, Henderson IR, Livrelli V, Gobert AP, Rosini R, Soriani M, Desvaux M. A secretome view of colonisation factors in Shiga toxin-encodingEscherichia coli(STEC): from enterohaemorrhagicE. coli(EHEC) to related enteropathotypes. FEMS Microbiol Lett 2016; 363:fnw179. [DOI: 10.1093/femsle/fnw179] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2016] [Indexed: 12/25/2022] Open
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222
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EseE of Edwardsiella tarda Augments Secretion of Translocon Protein EseC and Expression of the escC-eseE Operon. Infect Immun 2016; 84:2336-2344. [PMID: 27271743 DOI: 10.1128/iai.00106-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 05/26/2016] [Indexed: 02/07/2023] Open
Abstract
Edwardsiella tarda is an important Gram-negative pathogen that employs a type III secretion system (T3SS) to deliver effectors into host cells to facilitate bacterial survival and replication. These effectors are translocated into host cells through a translocon complex composed of three secreted proteins, namely, EseB, EseC, and EseD. The secretion of EseB and EseD requires a chaperone protein called EscC, whereas the secretion of EseC requires the chaperone EscA. In this study, we identified a novel protein (EseE) that also regulates the secretion of EseC. An eseE deletion mutant secreted much less EseC into supernatants, accompanied by increased EseC levels within bacterial cells. We also demonstrated that EseE interacted directly with EseC in a pulldown assay. Interestingly, EseC, EseE, and EscA were able to form a ternary complex, as revealed by pulldown and gel filtration assays. Of particular importance, the deletion of eseE resulted in decreased levels of EseB and EseD proteins in both the bacterial pellet and supernatant fraction. Furthermore, real-time PCR assays showed that EseE positively regulated the transcription of the translocon operon escC-eseE, comprising escC, eseB, escA, eseC, eseD, and eseE These effects of EseE on the translocon components/operon appeared to have a functional consequence, since the ΔeseE strain was outcompeted by wild-type E. tarda in a mixed infection in blue gourami fish. Collectively, our results demonstrate that EseE not only functions as a chaperone for EseC but also acts as a positive regulator controlling the expression of the translocon operon escC-eseE, thus contributing to the pathogenesis of E. tarda in fish.
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223
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Smith RP, Paxman JJ, Scanlon MJ, Heras B. Targeting Bacterial Dsb Proteins for the Development of Anti-Virulence Agents. Molecules 2016; 21:molecules21070811. [PMID: 27438817 PMCID: PMC6273893 DOI: 10.3390/molecules21070811] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 05/21/2016] [Accepted: 05/25/2016] [Indexed: 11/22/2022] Open
Abstract
Recent years have witnessed a dramatic increase in bacterial antimicrobial resistance and a decline in the development of novel antibiotics. New therapeutic strategies are urgently needed to combat the growing threat posed by multidrug resistant bacterial infections. The Dsb disulfide bond forming pathways are potential targets for the development of antimicrobial agents because they play a central role in bacterial pathogenesis. In particular, the DsbA/DsbB system catalyses disulfide bond formation in a wide array of virulence factors, which are essential for many pathogens to establish infections and cause disease. These redox enzymes are well placed as antimicrobial targets because they are taxonomically widespread, share low sequence identity with human proteins, and many years of basic research have provided a deep molecular understanding of these systems in bacteria. In this review, we discuss disulfide bond catalytic pathways in bacteria and their significance in pathogenesis. We also review the use of different approaches to develop inhibitors against Dsb proteins as potential anti-virulence agents, including fragment-based drug discovery, high-throughput screening and other structure-based drug discovery methods.
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Affiliation(s)
- Roxanne P Smith
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Vic 3083, Australia.
| | - Jason J Paxman
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Vic 3083, Australia.
| | - Martin J Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Royal Parade, Parkville, Vic 3052, Australia.
| | - Begoña Heras
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Kingsbury Drive, Bundoora, Vic 3083, Australia.
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224
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Elhenawy W, Bording-Jorgensen M, Valguarnera E, Haurat MF, Wine E, Feldman MF. LPS Remodeling Triggers Formation of Outer Membrane Vesicles in Salmonella. mBio 2016; 7:e00940-16. [PMID: 27406567 PMCID: PMC4958258 DOI: 10.1128/mbio.00940-16] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 06/09/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Outer membrane vesicles (OMV) are proposed to mediate multiple functions during pathogenesis and symbiosis. However, the mechanisms responsible for OMV formation remain poorly understood. It has been shown in eukaryotic membranes that lipids with an inverted-cone shape favor the formation of positive membrane curvatures. Based on these studies, we formulated the hypothesis that lipid A deacylation might impose shape modifications that result in the curvature of the outer membrane (OM) and subsequent OMV formation. We tested the effect of lipid A remodeling on OMV biogenesis employing Salmonella enterica serovar Typhimurium as a model organism. Expression of the lipid A deacylase PagL resulted in increased vesiculation, without inducing an envelope stress response. Mass spectrometry analysis revealed profound differences in the patterns of lipid A in OM and OMV, with accumulation of deacylated lipid A forms exclusively in OMV. OMV biogenesis by intracellular bacteria upon macrophage infection was drastically reduced in a pagL mutant strain. We propose a novel mechanism for OMV biogenesis requiring lipid A deacylation in the context of a multifactorial process that involves the orchestrated remodeling of the outer membrane. IMPORTANCE The role of lipid remodeling in vesiculation is well documented in eukaryotes. Similarly, bacteria produce membrane-derived vesicles; however, the molecular mechanisms underlying their production are yet to be determined. In this work, we investigated the role of outer membrane remodeling in OMV biogenesis in S Typhimurium. We showed that the expression of the lipid A deacylase PagL results in overvesiculation with deacylated lipid A accumulation exclusively in OMV. An S Typhimurium ΔpagL strain showed a significant reduction in intracellular OMV secretion relative to the wild-type strain. Our results suggest a novel mechanism for OMV biogenesis that involves outer membrane remodeling through lipid A modification. Understanding how OMV are produced by bacteria is important to advance our understanding of the host-pathogen interactions.
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Affiliation(s)
- Wael Elhenawy
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | | | - Ezequiel Valguarnera
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, St. Louis, Missouri, USA
| | - M Florencia Haurat
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Eytan Wine
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Mario F Feldman
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, St. Louis, Missouri, USA
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225
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Zigangirova NA, Kost EA, Didenko LV, Kapotina LN, Zayakin ES, Luyksaar SI, Morgunova EY, Fedina ED, Artyukhova OA, Samorodov AV, Kobets NV. A small-molecule compound belonging to a class of 2,4-disubstituted 1,3,4-thiadiazine-5-ones inhibits intracellular growth and persistence of Chlamydia trachomatis. J Med Microbiol 2016; 65:91-98. [PMID: 26489840 DOI: 10.1099/jmm.0.000189] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Chlamydia trachomatis is one of the most common sexually transmitted pathogens in the world and often causes chronic inflammatory diseases that are insensitive to antibiotics. The type 3 secretion system (T3SS) of pathogenic bacteria is a promising target for therapeutic intervention aimed at bacterial virulence and can be an attractive alternative for the treatment of chronic infections. Recently, we have shown that a small-molecule compound belonging to a class of 2,4-disubstituted 1,3,4-thiadiazine-5-ones produced through the chemical modification of the thiohydrazides of oxamic acids, designated CL-55, inhibited the intracellular growth of C. trachomatis in a T3SS-dependent manner. To assess the feasibility of CL-55 as a therapeutic agent, our aim was to determine which point(s) in the developmental cycle CL-55 affects. We found that CL-55 had no effect on the adhesion of elementary bodies (EBs) to host cells but significantly suppressed EB internalization. We further found that CL-55 inhibited the intracellular division of reticulate bodies (RBs). An ultrastructural analysis revealed loss of contact between the RBs and the inclusion membrane in the presence of CL-55. Finally, we found that our T3SS inhibitor prevented the persistence of Chlamydia in cell culture and its reversion to the infectious state. Our findings indicate that our T3SS inhibitor may be effective in the treatment of both productive and persistent infections.
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Affiliation(s)
- Naylia A Zigangirova
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Elena A Kost
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Lubov V Didenko
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Lydia N Kapotina
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Egor S Zayakin
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Sergei I Luyksaar
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Elena Y Morgunova
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Elena D Fedina
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Olga A Artyukhova
- Bauman Moscow State Technical University, 105005, 2nd Baumanskaya Str. 5, Moscow, Russian Federation
| | - Andrey V Samorodov
- Bauman Moscow State Technical University, 105005, 2nd Baumanskaya Str. 5, Moscow, Russian Federation
| | - Natalya V Kobets
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
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226
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Diepold A, Armitage JP. Type III secretion systems: the bacterial flagellum and the injectisome. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2015.0020. [PMID: 26370933 DOI: 10.1098/rstb.2015.0020] [Citation(s) in RCA: 139] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The flagellum and the injectisome are two of the most complex and fascinating bacterial nanomachines. At their core, they share a type III secretion system (T3SS), a transmembrane export complex that forms the extracellular appendages, the flagellar filament and the injectisome needle. Recent advances, combining structural biology, cryo-electron tomography, molecular genetics, in vivo imaging, bioinformatics and biophysics, have greatly increased our understanding of the T3SS, especially the structure of its transmembrane and cytosolic components, the transcriptional, post-transcriptional and functional regulation and the remarkable adaptivity of the system. This review aims to integrate these new findings into our current knowledge of the evolution, function, regulation and dynamics of the T3SS, and to highlight commonalities and differences between the two systems, as well as their potential applications.
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Affiliation(s)
- Andreas Diepold
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Judith P Armitage
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
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227
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Miller HK, Schwiesow L, Au-Yeung W, Auerbuch V. Hereditary Hemochromatosis Predisposes Mice to Yersinia pseudotuberculosis Infection Even in the Absence of the Type III Secretion System. Front Cell Infect Microbiol 2016; 6:69. [PMID: 27446816 PMCID: PMC4919332 DOI: 10.3389/fcimb.2016.00069] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 06/08/2016] [Indexed: 12/18/2022] Open
Abstract
The iron overload disorder hereditary hemochromatosis (HH) predisposes humans to serious disseminated infection with pathogenic Yersinia as well as several other pathogens. Recently, we showed that the iron-sulfur cluster coordinating transcription factor IscR is required for type III secretion in Y. pseudotuberculosis by direct control of the T3SS master regulator LcrF. In E. coli and Yersinia, IscR levels are predicted to be regulated by iron bioavailability, oxygen tension, and oxidative stress, such that iron depletion should lead to increased IscR levels. To investigate how host iron overload influences Y. pseudotuberculosis virulence and the requirement for the Ysc type III secretion system (T3SS), we utilized two distinct murine models of HH: hemojuvelin knockout mice that mimic severe, early-onset HH as well as mice with the HfeC282Y∕C282Y mutation carried by 10% of people of Northern European descent, associated with adult-onset HH. Hjv−∕− and HfeC282Y∕C282Y transgenic mice displayed enhanced colonization of deep tissues by Y. pseudotuberculosis following oral inoculation, recapitulating enhanced susceptibility of humans with HH to disseminated infection with enteropathogenic Yersinia. Importantly, HH mice orally infected with Y. pseudotuberculosis lacking the T3SS-encoding virulence plasmid, pYV, displayed increased deep tissue colonization relative to wildtype mice. Consistent with previous reports using monocytes from HH vs. healthy donors, macrophages isolated from HfeC282Y∕C282Y mice were defective in Yersinia uptake compared to wildtype macrophages, indicating that the anti-phagocytic property of the Yersinia T3SS plays a less important role in HH animals. These data suggest that Yersinia may rely on distinct virulence factors to cause disease in healthy vs. HH hosts.
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Affiliation(s)
- Halie K Miller
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz Santa Cruz, CA, USA
| | - Leah Schwiesow
- Department of Molecular, Cell, and Developmental Biology, University of California Santa Cruz Santa Cruz, CA, USA
| | - Winnie Au-Yeung
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz Santa Cruz, CA, USA
| | - Victoria Auerbuch
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz Santa Cruz, CA, USA
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228
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Anantharajah A, Mingeot-Leclercq MP, Van Bambeke F. Targeting the Type Three Secretion System in Pseudomonas aeruginosa. Trends Pharmacol Sci 2016; 37:734-749. [PMID: 27344210 DOI: 10.1016/j.tips.2016.05.011] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/15/2016] [Accepted: 05/17/2016] [Indexed: 12/11/2022]
Abstract
The injectisome type three secretion system (T3SS) is a major virulence factor in Pseudomonas aeruginosa. This bacterium is responsible for severe infections in immunosuppressed or cystic fibrosis patients and has become resistant to many antibiotics. Inhibitors of T3SS may therefore constitute an innovative therapeutic target. After a brief description of the T3SS and its regulation, this review presents strategies to inhibit T3SS-mediated toxicity and describes the main families of existing inhibitors. Over the past few years, 12 classes of small-molecule inhibitors and two types of antibody have been discovered and evaluated in vitro for their capacity to inhibit T3SS expression or function, and to protect host cells from T3SS-mediated cytotoxicity. While only one small molecule has been tested in vivo, a bifunctional antibody targeting both the translocation apparatus of the T3SS and a surface polysaccharide is currently in Phase II clinical trials.
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Affiliation(s)
- Ahalieyah Anantharajah
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Marie-Paule Mingeot-Leclercq
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Françoise Van Bambeke
- Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium.
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229
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Abstract
The human pathogens
Yersinia pseudotuberculosis and
Yersinia enterocolitica cause enterocolitis, while
Yersinia pestis is responsible for pneumonic, bubonic, and septicaemic plague. All three share an infection strategy that relies on a virulence factor arsenal to enable them to enter, adhere to, and colonise the host while evading host defences to avoid untimely clearance. Their arsenal includes a number of adhesins that allow the invading pathogens to establish a foothold in the host and to adhere to specific tissues later during infection. When the host innate immune system has been activated, all three pathogens produce a structure analogous to a hypodermic needle. In conjunction with the translocon, which forms a pore in the host membrane, the channel that is formed enables the transfer of six ‘effector’ proteins into the host cell cytoplasm. These proteins mimic host cell proteins but are more efficient than their native counterparts at modifying the host cell cytoskeleton, triggering the host cell suicide response. Such a sophisticated arsenal ensures that yersiniae maintain the upper hand despite the best efforts of the host to counteract the infecting pathogen.
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Affiliation(s)
- Steve Atkinson
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, UK
| | - Paul Williams
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, UK
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230
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Kinoshita M, Nakanishi Y, Furukawa Y, Namba K, Imada K, Minamino T. Rearrangements of α-helical structures of FlgN chaperone control the binding affinity for its cognate substrates during flagellar type III export. Mol Microbiol 2016; 101:656-70. [PMID: 27178222 DOI: 10.1111/mmi.13415] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2016] [Indexed: 11/29/2022]
Abstract
The bacterial flagellar type III export chaperones not only act as bodyguards to protect their cognate substrates from aggregation and proteolysis in the cytoplasm but also ensure the order of export through their interactions with an export gate protein FlhA. FlgN chaperone binds to FlgK and FlgL with nanomolar affinity and transfers them to FlhA for their efficient and rapid transport for the formation of the hook-filament junction zone. However, it remains unknown how FlgN releases FlgK and FlgL at the FlhA export gate platform in a timely manner. Here, we have solved the crystal structure of Salmonella FlgN at 2.3 Å resolution and carried out structure-based functional analyses. FlgN consists of three α helices, α1, α2 and α3. Helix α1 adopts two distinct, extended and bent conformations through the conformational change of N-loop between α1 and α2. The N-loop deletion not only increases the probability of FlgN dimer formation but also abolish the interaction between FlgN and FlgK. Highly conserved Asn-92, Asn-95 and Ile-103 residues in helix α3 are involved in the strong interaction with FlgK. We propose that the N-loop coordinates helical rearrangements of FlgN with the association and dissociation of its cognate substrates during their export.
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Affiliation(s)
- Miki Kinoshita
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan
| | - Yuki Nakanishi
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan
| | - Yukio Furukawa
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Quantitative Biology Center, Riken, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Katsumi Imada
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan
| | - Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
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231
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Mitchell G, Chen C, Portnoy DA. Strategies Used by Bacteria to Grow in Macrophages. Microbiol Spectr 2016; 4:10.1128/microbiolspec.MCHD-0012-2015. [PMID: 27337444 PMCID: PMC4922531 DOI: 10.1128/microbiolspec.mchd-0012-2015] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Indexed: 12/24/2022] Open
Abstract
Intracellular bacteria are often clinically relevant pathogens that infect virtually every cell type found in host organisms. However, myeloid cells, especially macrophages, constitute the primary cells targeted by most species of intracellular bacteria. Paradoxically, macrophages possess an extensive antimicrobial arsenal and are efficient at killing microbes. In addition to their ability to detect and signal the presence of pathogens, macrophages sequester and digest microorganisms using the phagolysosomal and autophagy pathways or, ultimately, eliminate themselves through the induction of programmed cell death. Consequently, intracellular bacteria influence numerous host processes and deploy sophisticated strategies to replicate within these host cells. Although most intracellular bacteria have a unique intracellular life cycle, these pathogens are broadly categorized into intravacuolar and cytosolic bacteria. Following phagocytosis, intravacuolar bacteria reside in the host endomembrane system and, to some extent, are protected from the host cytosolic innate immune defenses. However, the intravacuolar lifestyle requires the generation and maintenance of unique specialized bacteria-containing vacuoles and involves a complex network of host-pathogen interactions. Conversely, cytosolic bacteria escape the phagolysosomal pathway and thrive in the nutrient-rich cytosol despite the presence of host cell-autonomous defenses. The understanding of host-pathogen interactions involved in the pathogenesis of intracellular bacteria will continue to provide mechanistic insights into basic cellular processes and may lead to the discovery of novel therapeutics targeting infectious and inflammatory diseases.
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Affiliation(s)
- Gabriel Mitchell
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Chen Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Daniel A. Portnoy
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA
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232
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Borges V, Nunes A, Sampaio DA, Vieira L, Machado J, Simões MJ, Gonçalves P, Gomes JP. Legionella pneumophila strain associated with the first evidence of person-to-person transmission of Legionnaires' disease: a unique mosaic genetic backbone. Sci Rep 2016; 6:26261. [PMID: 27196677 PMCID: PMC4872527 DOI: 10.1038/srep26261] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 04/29/2016] [Indexed: 01/23/2023] Open
Abstract
A first strong evidence of person-to-person transmission of Legionnaires’ Disease (LD) was recently reported. Here, we characterize the genetic backbone of this case-related Legionella pneumophila strain (“PtVFX/2014”), which also caused a large outbreak of LD. PtVFX/2014 is phylogenetically divergent from the most worldwide studied outbreak-associated L. pneumophila subspecies pneumophila serogroup 1 strains. In fact, this strain is also from serogroup 1, but belongs to the L. pneumophila subspecies fraseri. Its genomic mosaic backbone reveals eight horizontally transferred regions encompassing genes, for instance, involved in lipopolysaccharide biosynthesis or encoding virulence-associated Dot/Icm type IVB secretion system (T4BSS) substrates. PtVFX/2014 also inherited a rare ~65 kb pathogenicity island carrying virulence factors and detoxifying enzymes believed to contribute to the emergence of best-fitted strains in water reservoirs and in human macrophages, as well as a inter-species transferred (from L. oakridgensis) ~37.5 kb genomic island (harboring a lvh/lvr T4ASS cluster) that had never been found intact within L. pneumophila species. PtVFX/2014 encodes another lvh/lvr cluster near to CRISPR-associated genes, which may boost L. pneumophila transition from an environmental bacterium to a human pathogen. Overall, this unique genomic make-up may impact PtVFX/2014 ability to adapt to diverse environments, and, ultimately, to be transmitted and cause human disease.
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Affiliation(s)
- Vítor Borges
- Bioinformatics Unit and Research Unit, National Institute of Health, Lisbon, Portugal
| | - Alexandra Nunes
- Bioinformatics Unit and Research Unit, National Institute of Health, Lisbon, Portugal
| | - Daniel A Sampaio
- Innovation and Technology Unit, National Institute of Health, Lisbon, Portugal
| | - Luís Vieira
- Innovation and Technology Unit, National Institute of Health, Lisbon, Portugal
| | - Jorge Machado
- Coordination of the Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - Maria J Simões
- National Reference Laboratory for Legionella, National Institute of Health, Lisbon, Portugal
| | - Paulo Gonçalves
- National Reference Laboratory for Legionella, National Institute of Health, Lisbon, Portugal
| | - João P Gomes
- Bioinformatics Unit and Research Unit, National Institute of Health, Lisbon, Portugal
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233
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Weiner A, Mellouk N, Lopez-Montero N, Chang YY, Souque C, Schmitt C, Enninga J. Macropinosomes are Key Players in Early Shigella Invasion and Vacuolar Escape in Epithelial Cells. PLoS Pathog 2016; 12:e1005602. [PMID: 27182929 PMCID: PMC4868309 DOI: 10.1371/journal.ppat.1005602] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 04/05/2016] [Indexed: 01/30/2023] Open
Abstract
Intracellular pathogens include all viruses, many bacteria and parasites capable of invading and surviving within host cells. Key to survival is the subversion of host cell pathways by the pathogen for the purpose of propagation and evading the immune system. The intracellular bacterium Shigella flexneri, the causative agent of bacillary dysentery, invades host cells in a vacuole that is subsequently ruptured to allow growth of the pathogen within the host cytoplasm. S. flexneri invasion has been classically described as a macropinocytosis-like process, however the underlying details and the role of macropinosomes in the intracellular bacterial lifestyle have remained elusive. We applied dynamic imaging and advanced large volume correlative light electron microscopy (CLEM) to study the highly transient events of S. flexneri's early invasion into host epithelial cells and elucidate some of its fundamental features. First, we demonstrate a clear distinction between two compartments formed during the first step of invasion: the bacterial containing vacuole and surrounding macropinosomes, often considered identical. Next, we report a functional link between macropinosomes and the process of vacuolar rupture, demonstrating that rupture timing is dependent on the availability of macropinosomes as well as the activity of the small GTPase Rab11 recruited directly to macropinosomes. We go on to reveal that the bacterial containing vacuole and macropinosomes come into direct contact at the onset of vacuolar rupture. Finally, we demonstrate that S. flexneri does not subvert pre-existing host endocytic vesicles during the invasion steps leading to vacuolar rupture, and propose that macropinosomes are the major compartment involved in these events. These results provide the basis for a new model of the early steps of S. flexneri epithelial cell invasion, establishing a different view of the enigmatic process of cytoplasmic access by invasive bacterial pathogens.
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Affiliation(s)
- Allon Weiner
- Institut Pasteur, Dynamics of Host-Pathogen interactions Unit, Paris, France
- * E-mail: (AW); (JE)
| | - Nora Mellouk
- Institut Pasteur, Dynamics of Host-Pathogen interactions Unit, Paris, France
| | | | - Yuen-Yan Chang
- Institut Pasteur, Dynamics of Host-Pathogen interactions Unit, Paris, France
| | - Célia Souque
- Institut Pasteur, Dynamics of Host-Pathogen interactions Unit, Paris, France
| | | | - Jost Enninga
- Institut Pasteur, Dynamics of Host-Pathogen interactions Unit, Paris, France
- * E-mail: (AW); (JE)
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234
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Sun WSW, Chen JW, Wu YC, Tsai HY, Kuo YL, Syu WJ. Expression Regulation of Polycistronic lee3 Genes of Enterohaemorrhagic Escherichia coli. PLoS One 2016; 11:e0155578. [PMID: 27182989 PMCID: PMC4868261 DOI: 10.1371/journal.pone.0155578] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 05/01/2016] [Indexed: 01/21/2023] Open
Abstract
Enterohaemorrhagic Escherichia coli O157:H7 (EHEC) carries a pathogenic island LEE that is consisted mainly of five polycistronic operons. In the lee3 operon, mpc is the first gene and has been reported to down regulate the type-3 secretion system of EHEC when its gene product is over-expressed. Furthermore, mpc has been suggested to have a regulation function via translation but the mechanism remains unclear. To clarify this hypothesis, we dissected the polycistron and examined the translated products. We conclude that translation of mpc detrimentally governs the translation of the second gene, escV, which in turn affects the translation of the third gene, escN. Then sequentially, escN affects the expression of the downstream genes. Furthermore, we located a critical cis element within the mpc open-reading frame that plays a negative role in the translation-dependent regulation of lee3. Using qRT-PCR, we found that the amount of mpc RNA transcript present in EHEC was relatively limited when compared to any other genes within lee3. Taken together, when the transcription of LEE is activated, expression of mpc is tightly controlled by a restriction of the RNA transcript of mpc, translation of which is then critical for the efficient production of the operon’s downstream gene products.
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Affiliation(s)
- Wei-Sheng W. Sun
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan, R.O.C
- Taiwan International Graduate Program in Molecular Medicine, Academia Sinica, Taipei, Taiwan, R.O.C
| | - Jenn-Wei Chen
- Department of Microbiology and Immunology, National Cheng-Kung University, Tainan, Taiwan, R.O.C
| | - Yi-Chih Wu
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, R.O.C
| | - Hsing-Yuan Tsai
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, R.O.C
| | - Yu-Liang Kuo
- Department of Medical Imaging and Radiological Sciences, Chung Shan Medical University, Taichung, Taiwan, R.O.C
- Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung, Taiwan, R.O.C
| | - Wan-Jr Syu
- Taiwan International Graduate Program in Molecular Medicine, Academia Sinica, Taipei, Taiwan, R.O.C
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan, R.O.C
- * E-mail:
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235
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Wang G, Xia Y, Xiong Z, Zhang H, Ai L. Use of a Novel Report Protein to Study the Secretion Signal of Flagellin in Bacillus subtilis. Curr Microbiol 2016; 73:242-7. [PMID: 27154466 DOI: 10.1007/s00284-016-1054-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 03/21/2016] [Indexed: 01/16/2023]
Abstract
Flagellin (also called Hag) is the main component of bacterial flagellum and is transported across the cytoplasmic membrane by flagellar secretion apparatus. Because flagella play an essential role in the pathogenesis of numerous pathogens, the flagellins of Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Campylobacter jejuni, and Vibrio cholerae have been intensively studied; however, very few studies have focused on the flagellin of Bacillus subtilis, which is considered to be a model organism with which to study the secretion of bacteria and is used on an industrial scale for the secretion of proteins. The signal of B. subtilis flagellin is still debated. This study was performed to seek the export signals of flagellin from B. subtilis. The naturally nonsecretory, intrinsically disordered domain of nucleoskeletal-like protein (Nsp) was used as the reporter protein. Our results demonstrate that the export signal is contained within the first 50 amino acids of B. subtilis flagellin. Nsp is easily degraded inside the cell and can be exported into culture medium with the aid of the signal of flagellin. This method provides a new potential strategy for the expression of proteins with high proteolytic susceptibility via fusion to export signals.
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Affiliation(s)
- Guangqiang Wang
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, People's Republic of China
| | - Yongjun Xia
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, People's Republic of China
| | - Zhiqiang Xiong
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, People's Republic of China
| | - Hui Zhang
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, People's Republic of China
| | - Lianzhong Ai
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, 200093, People's Republic of China.
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236
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Kaur K, Chatterjee S, De Guzman RN. Characterization of the Shigella and Salmonella Type III Secretion System Tip-Translocon Protein-Protein Interaction by Paramagnetic Relaxation Enhancement. Chembiochem 2016; 17:745-752. [PMID: 26749041 PMCID: PMC4918631 DOI: 10.1002/cbic.201500556] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Indexed: 12/21/2022]
Abstract
Many Gram-negative pathogens, such as Shigella and Salmonella, assemble the type III secretion system (T3SS) to inject virulence proteins directly into eukaryotic cells to initiate infectious diseases. The needle apparatus of the T3SS consists of a base, an extracellular needle, a tip protein complex, and a translocon. The atomic structure of the assembled tip complex and the translocon is unknown. Here, we show by NMR paramagnetic relaxation enhancement (PRE) that the mixed α-β domain at the distal region of the Shigella and Salmonella tip proteins interacts with the N-terminal ectodomain of their major translocon proteins. Our results reveal the binding surfaces involved in the tip-translocon protein-protein interaction and provide insights about the assembly of the needle apparatus of the T3SS.
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Affiliation(s)
- Kawaljit Kaur
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA
| | - Srirupa Chatterjee
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA
| | - Roberto N De Guzman
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA
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237
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Nariya MK, Israeli J, Shi JJ, Deeds EJ. Mathematical Model for Length Control by the Timing of Substrate Switching in the Type III Secretion System. PLoS Comput Biol 2016; 12:e1004851. [PMID: 27078235 PMCID: PMC4831731 DOI: 10.1371/journal.pcbi.1004851] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 03/06/2016] [Indexed: 12/28/2022] Open
Abstract
Type III Secretion Systems (T3SS) are complex bacterial structures that provide gram-negative pathogens with a unique virulence mechanism whereby they grow a needle-like structure in order to inject bacterial effector proteins into the cytoplasm of a host cell. Numerous experiments have been performed to understand the structural details of this nanomachine during the past decade. Despite the concerted efforts of molecular and structural biologists, several crucial aspects of the assembly of this structure, such as the regulation of the length of the needle itself, remain unclear. In this work, we used a combination of mathematical and computational techniques to better understand length control based on the timing of substrate switching, which is a possible mechanism for how bacteria ensure that the T3SS needles are neither too short nor too long. In particular, we predicted the form of the needle length distribution based on this mechanism, and found excellent agreement with available experimental data from Salmonella typhimurium with only a single free parameter. Although our findings provide preliminary evidence in support of the substrate switching model, they also make a set of quantitative predictions that, if tested experimentally, would assist in efforts to unambiguously characterize the regulatory mechanisms that control the growth of this crucial virulence factor.
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Affiliation(s)
- Maulik K. Nariya
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas, United States of America
| | - Johnny Israeli
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas, United States of America
| | - Jack J. Shi
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas, United States of America
| | - Eric J. Deeds
- Center for Computational Biology, University of Kansas, Lawrence, Kansas, United States of America
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States of America
- Sante Fe Institute, Santa Fe, New Mexico, United States of America
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238
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Law RJ, Law HT, Scurll JM, Scholz R, Santos AS, Shames SR, Deng W, Croxen MA, Li Y, de Hoog CL, van der Heijden J, Foster LJ, Guttman JA, Finlay BB. Quantitative Mass Spectrometry Identifies Novel Host Binding Partners for Pathogenic Escherichia coli Type III Secretion System Effectors. J Proteome Res 2016; 15:1613-22. [DOI: 10.1021/acs.jproteome.6b00074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Hong T. Law
- Department
of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | | | | | | | | | | | | | | | | | | | | | - Julian A. Guttman
- Department
of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
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239
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Coleman MA, Cappuccio JA, Blanchette CD, Gao T, Arroyo ES, Hinz AK, Bourguet FA, Segelke B, Hoeprich PD, Huser T, Laurence TA, Motin VL, Chromy BA. Expression and Association of the Yersinia pestis Translocon Proteins, YopB and YopD, Are Facilitated by Nanolipoprotein Particles. PLoS One 2016; 11:e0150166. [PMID: 27015536 PMCID: PMC4807764 DOI: 10.1371/journal.pone.0150166] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 02/10/2016] [Indexed: 12/18/2022] Open
Abstract
Yersinia pestis enters host cells and evades host defenses, in part, through interactions between Yersinia pestis proteins and host membranes. One such interaction is through the type III secretion system, which uses a highly conserved and ordered complex for Yersinia pestis outer membrane effector protein translocation called the injectisome. The portion of the injectisome that interacts directly with host cell membranes is referred to as the translocon. The translocon is believed to form a pore allowing effector molecules to enter host cells. To facilitate mechanistic studies of the translocon, we have developed a cell-free approach for expressing translocon pore proteins as a complex supported in a bilayer membrane mimetic nano-scaffold known as a nanolipoprotein particle (NLP) Initial results show cell-free expression of Yersinia pestis outer membrane proteins YopB and YopD was enhanced in the presence of liposomes. However, these complexes tended to aggregate and precipitate. With the addition of co-expressed (NLP) forming components, the YopB and/or YopD complex was rendered soluble, increasing the yield of protein for biophysical studies. Biophysical methods such as Atomic Force Microscopy and Fluorescence Correlation Spectroscopy were used to confirm that the soluble YopB/D complex was associated with NLPs. An interaction between the YopB/D complex and NLP was validated by immunoprecipitation. The YopB/D translocon complex embedded in a NLP provides a platform for protein interaction studies between pathogen and host proteins. These studies will help elucidate the poorly understood mechanism which enables this pathogen to inject effector proteins into host cells, thus evading host defenses.
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Affiliation(s)
- Matthew A. Coleman
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
- University of California Davis, NSF, Center for Biophotonics, Sacramento, CA, United States of America, 95817
- * E-mail: (MAC); (BAC)
| | - Jenny A. Cappuccio
- Humboldt State University, Department of Chemistry, Arcata, CA, United States of America, 95521
| | - Craig D. Blanchette
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Tingjuan Gao
- University of California Davis, NSF, Center for Biophotonics, Sacramento, CA, United States of America, 95817
| | - Erin S. Arroyo
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Angela K. Hinz
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Feliza A. Bourguet
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Brent Segelke
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Paul D. Hoeprich
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Thomas Huser
- University of California Davis, NSF, Center for Biophotonics, Sacramento, CA, United States of America, 95817
| | - Ted A. Laurence
- Lawrence Livermore National Laboratory, Livermore, CA, United States of America, 94550
| | - Vladimir L. Motin
- University of Texas Medical Branch, Galveston, TX, United States of America, 77555
| | - Brett A. Chromy
- University of California Davis, NSF, Center for Biophotonics, Sacramento, CA, United States of America, 95817
- * E-mail: (MAC); (BAC)
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240
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Wonnenberg B, Bischoff M, Beisswenger C, Dinh T, Bals R, Singh B, Tschernig T. The role of IL-1β in Pseudomonas aeruginosa in lung infection. Cell Tissue Res 2016; 364:225-9. [PMID: 26984603 DOI: 10.1007/s00441-016-2387-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 02/25/2016] [Indexed: 12/19/2022]
Abstract
This mini-review examines the role of the pro-inflammatory cytokine interleukin (IL)-1β in the interaction of Pseudomonas aeruginosa and the host immune system during lung infection. Different studies show that the reduction of the inflammatory response, especially a decrease in IL-1β, leads to a better outcome in acute lung infection with this bacterium. This includes a higher survival rate, reduced damage to the lung tissue and, in particular, a better clearance of the airways and the tissue of the lungs from P. aeruginosa.
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Affiliation(s)
- B Wonnenberg
- Department of Anatomy and Cell Biology, Saarland University, Kirrberger Strasse, 66424, Homburg, Saar, Germany
| | - M Bischoff
- Institute of Medical Microbiology and Hygiene, Saarland University, Homburg, Germany
| | - C Beisswenger
- Department of Internal Medicine V, Pneumology, Allergology and Respiratory Critical Care Medicine, Saarland University, Homburg, Germany
| | - T Dinh
- Department of Experimental Pneumology and Allergology, Saarland University, Homburg, Germany
| | - R Bals
- Department of Internal Medicine V, Pneumology, Allergology and Respiratory Critical Care Medicine, Saarland University, Homburg, Germany
| | - B Singh
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
| | - T Tschernig
- Department of Anatomy and Cell Biology, Saarland University, Kirrberger Strasse, 66424, Homburg, Saar, Germany.
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241
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Gold V, Kudryashev M. Recent progress in structure and dynamics of dual-membrane-spanning bacterial nanomachines. Curr Opin Struct Biol 2016; 39:1-7. [PMID: 26995496 DOI: 10.1016/j.sbi.2016.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/03/2016] [Accepted: 03/04/2016] [Indexed: 02/05/2023]
Abstract
Advances in hard-ware and soft-ware for electron cryo-microscopy and tomography have provided unprecedented structural insights into large protein complexes in bacterial membranes. Tomographic volumes of native complexes in situ, combined with other structural and functional data, reveal functionally important conformational changes. Here, we review recent progress in elucidating the structure and mechanism of dual-membrane-spanning nanomachines involved in bacterial motility, adhesion, pathogenesis and biofilm formation, including the type IV pilus assembly machinery and the type III and VI secretions systems. We highlight how these new structural data shed light on the assembly and action of such machines and discuss future directions for more detailed mechanistic understanding of these massive, fascinating complexes.
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Affiliation(s)
- Vicki Gold
- Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438 Frankfurt am Main, Germany.
| | - Mikhail Kudryashev
- Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438 Frankfurt am Main, Germany; Buchmann Institute for Molecular Life Sciences, Goethe University of Frankfurt, Max-von-Laue Str. 17, 60438 Frankfurt am Main, Germany.
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242
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Identification of protein secretion systems in bacterial genomes. Sci Rep 2016; 6:23080. [PMID: 26979785 PMCID: PMC4793230 DOI: 10.1038/srep23080] [Citation(s) in RCA: 242] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 02/24/2016] [Indexed: 01/08/2023] Open
Abstract
Bacteria with two cell membranes (diderms) have evolved complex systems for protein secretion. These systems were extensively studied in some model bacteria, but the characterisation of their diversity has lagged behind due to lack of standard annotation tools. We built online and standalone computational tools to accurately predict protein secretion systems and related appendages in bacteria with LPS-containing outer membranes. They consist of models describing the systems’ components and genetic organization to be used with MacSyFinder to search for T1SS-T6SS, T9SS, flagella, Type IV pili and Tad pili. We identified ~10,000 candidate systems in bacterial genomes, where T1SS and T5SS were by far the most abundant and widespread. All these data are made available in a public database. The recently described T6SSiii and T9SS were restricted to Bacteroidetes, and T6SSii to Francisella. The T2SS, T3SS, and T4SS were frequently encoded in single-copy in one locus, whereas most T1SS were encoded in two loci. The secretion systems of diderm Firmicutes were similar to those found in other diderms. Novel systems may remain to be discovered, since some clades of environmental bacteria lacked all known protein secretion systems. Our models can be fully customized, which should facilitate the identification of novel systems.
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243
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Insight into the flagella type III export revealed by the complex structure of the type III ATPase and its regulator. Proc Natl Acad Sci U S A 2016; 113:3633-8. [PMID: 26984495 DOI: 10.1073/pnas.1524025113] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
FliI and FliJ form the FliI6FliJ ATPase complex of the bacterial flagellar export apparatus, a member of the type III secretion system. The FliI6FliJ complex is structurally similar to the α3β3γ complex of F1-ATPase. The FliH homodimer binds to FliI to connect the ATPase complex to the flagellar base, but the details are unknown. Here we report the structure of the homodimer of a C-terminal fragment of FliH (FliHC2) in complex with FliI. FliHC2 shows an unusually asymmetric homodimeric structure that markedly resembles the peripheral stalk of the A/V-type ATPases. The FliHC2-FliI hexamer model reveals that the C-terminal domains of the FliI ATPase face the cell membrane in a way similar to the F/A/V-type ATPases. We discuss the mechanism of flagellar ATPase complex formation and a common origin shared by the type III secretion system and the F/A/V-type ATPases.
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244
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Guignot J, Tran Van Nhieu G. Bacterial Control of Pores Induced by the Type III Secretion System: Mind the Gap. Front Immunol 2016; 7:84. [PMID: 27014264 PMCID: PMC4783396 DOI: 10.3389/fimmu.2016.00084] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 02/22/2016] [Indexed: 12/27/2022] Open
Abstract
Type III secretion systems (T3SSs) are specialized secretion apparatus involved in the virulence of many Gram-negative pathogens, enabling the injection of bacterial type III effectors into host cells. The T3SS-dependent injection of effectors requires the insertion into host cell membranes of a pore-forming "translocon," whose effects on cell responses remain ill-defined. As opposed to pore-forming toxins that damage host cell plasma membranes and induce cell survival mechanisms, T3SS-dependent pore formation is transient, being regulated by cell membrane repair mechanisms or bacterial effectors. Here, we review host cell responses to pore formation induced by T3SSs associated with the loss of plasma membrane integrity and regulation of innate immunity. We will particularly focus on recent advances in mechanisms controlling pore formation and the activity of the T3SS linked to type III effectors or bacterial proteases. The implications of the regulation of the T3SS translocon activity during the infectious process will be discussed.
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Affiliation(s)
- Julie Guignot
- Equipe Communication Intercellulaire et Infections Microbiennes, Centre de Recherche Interdisciplinaire en Biologie (CIRB), Collège de France, Paris, France; Institut National de la Santé et de la Recherche Médicale U1050, Paris, France; Centre National de la Recherche Scientifique UMR7241, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres, Paris, France
| | - Guy Tran Van Nhieu
- Equipe Communication Intercellulaire et Infections Microbiennes, Centre de Recherche Interdisciplinaire en Biologie (CIRB), Collège de France, Paris, France; Institut National de la Santé et de la Recherche Médicale U1050, Paris, France; Centre National de la Recherche Scientifique UMR7241, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Sciences et Lettres, Paris, France
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245
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Minamino T, Morimoto YV, Hara N, Aldridge PD, Namba K. The Bacterial Flagellar Type III Export Gate Complex Is a Dual Fuel Engine That Can Use Both H+ and Na+ for Flagellar Protein Export. PLoS Pathog 2016; 12:e1005495. [PMID: 26943926 PMCID: PMC4778876 DOI: 10.1371/journal.ppat.1005495] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/15/2016] [Indexed: 11/22/2022] Open
Abstract
The bacterial flagellar type III export apparatus utilizes ATP and proton motive force (PMF) to transport flagellar proteins to the distal end of the growing flagellar structure for self-assembly. The transmembrane export gate complex is a H+–protein antiporter, of which activity is greatly augmented by an associated cytoplasmic ATPase complex. Here, we report that the export gate complex can use sodium motive force (SMF) in addition to PMF across the cytoplasmic membrane to drive protein export. Protein export was considerably reduced in the absence of the ATPase complex and a pH gradient across the membrane, but Na+ increased it dramatically. Phenamil, a blocker of Na+ translocation, inhibited protein export. Overexpression of FlhA increased the intracellular Na+ concentration in the presence of 100 mM NaCl but not in its absence, suggesting that FlhA acts as a Na+ channel. In wild-type cells, however, neither Na+ nor phenamil affected protein export, indicating that the Na+ channel activity of FlhA is suppressed by the ATPase complex. We propose that the export gate by itself is a dual fuel engine that uses both PMF and SMF for protein export and that the ATPase complex switches this dual fuel engine into a PMF-driven export machinery to become much more robust against environmental changes in external pH and Na+ concentration. For construction of the bacterial flagellum beyond the inner and outer membranes, the flagellar type III export apparatus transports fourteen flagellar proteins with their copy numbers ranging from a few to tens of thousands to the distal growing end of the flagellar structure. The export apparatus consists of a transmembrane export gate complex and a cytoplasmic ATPase complex. Here, we show that the export engine of the flagellar type III export apparatus is robust in maintaining its export activity against internal and external perturbations arising from genetic variations and/or environmental changes. When the cytoplasmic ATPase complex is absent, the export gate complex is able to utilize sodium motive force (SMF) across the cytoplasmic membrane as a fuel in addition to proton motive force (PMF). However, the export gate utilizes only PMF as the energy source when the ATPase complex is active. An export gate protein FlhA shows an intrinsic ion channel activity. These observations suggest that the export gate intrinsically uses both PMF and SMF for protein export and that the ATPase complex switches the export gate into a highly efficient PMF-driven export engine to become much more robust against environmental perturbations.
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Affiliation(s)
- Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamadaoka, Suita, Osaka, Japan
- * E-mail: (TM); (KN)
| | - Yusuke V. Morimoto
- Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamadaoka, Suita, Osaka, Japan
- Quantitative Biology Center, RIKEN, 6-2-3 Furuedai, Suita, Osaka, Japan
| | - Noritaka Hara
- Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamadaoka, Suita, Osaka, Japan
| | - Phillip D. Aldridge
- Centre for Bacterial Cell Biology, Medical Sciences New Building, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, 1–3 Yamadaoka, Suita, Osaka, Japan
- Quantitative Biology Center, RIKEN, 6-2-3 Furuedai, Suita, Osaka, Japan
- * E-mail: (TM); (KN)
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246
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Habenstein B, Loquet A. Solid-state NMR: An emerging technique in structural biology of self-assemblies. Biophys Chem 2016; 210:14-26. [DOI: 10.1016/j.bpc.2015.07.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Accepted: 07/08/2015] [Indexed: 12/13/2022]
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247
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Minamino T, Kinoshita M, Inoue Y, Morimoto YV, Ihara K, Koya S, Hara N, Nishioka N, Kojima S, Homma M, Namba K. FliH and FliI ensure efficient energy coupling of flagellar type III protein export in Salmonella. Microbiologyopen 2016; 5:424-35. [PMID: 26916245 PMCID: PMC4905995 DOI: 10.1002/mbo3.340] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 01/04/2016] [Accepted: 01/14/2016] [Indexed: 11/29/2022] Open
Abstract
For construction of the bacterial flagellum, flagellar proteins are exported via its specific export apparatus from the cytoplasm to the distal end of the growing flagellar structure. The flagellar export apparatus consists of a transmembrane (TM) export gate complex and a cytoplasmic ATPase complex consisting of FliH, FliI, and FliJ. FlhA is a TM export gate protein and plays important roles in energy coupling of protein translocation. However, the energy coupling mechanism remains unknown. Here, we performed a cross‐complementation assay to measure robustness of the energy transduction system of the export apparatus against genetic perturbations. Vibrio FlhA restored motility of a Salmonella ΔflhA mutant but not that of a ΔfliH‐fliI flhB(P28T) ΔflhA mutant. The flgM mutations significantly increased flagellar gene expression levels, allowing Vibrio FlhA to exert its export activity in the ΔfliH‐fliI flhB(P28T) ΔflhA mutant. Pull‐down assays revealed that the binding affinities of Vibrio FlhA for FliJ and the FlgN–FlgK chaperone–substrate complex were much lower than those of Salmonella FlhA. These suggest that Vibrio FlhA requires the support of FliH and FliI to efficiently and properly interact with FliJ and the FlgN–FlgK complex. We propose that FliH and FliI ensure robust and efficient energy coupling of protein export during flagellar assembly.
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Affiliation(s)
- Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Miki Kinoshita
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yumi Inoue
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yusuke V Morimoto
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Quantitative Biology Center, RIKEN, 6-2-3 Furuedai, Suita, Osaka, 565-0874, Japan
| | - Kunio Ihara
- Center for Gene Research, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Satomi Koya
- Departments of Food Science and Nutrition, Faculty of Human life and Science, Doshisha Women's College of Liberal Arts, Kyoto, 602-0893, Japan
| | - Noritaka Hara
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Noriko Nishioka
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Center for Gene Research, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
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248
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Engel AC, Herbst F, Kerres A, Galle JN, Hegemann JH. The Type III Secretion System-Related CPn0809 from Chlamydia pneumoniae. PLoS One 2016; 11:e0148509. [PMID: 26895250 PMCID: PMC4760673 DOI: 10.1371/journal.pone.0148509] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 01/20/2016] [Indexed: 11/19/2022] Open
Abstract
Chlamydia pneumoniae is an intracellular Gram-negative bacterium that possesses a type III secretion system (T3SS), which enables the pathogen to deliver, in a single step, effector proteins for modulation of host-cell functions into the human host cell cytosol to establish a unique intracellular niche for replication. The translocon proteins located at the top of the T3SS needle filament are essential for its function, as they form pores in the host-cell membrane. Interestingly, unlike other Gram-negative bacteria, C. pneumoniae has two putative translocon operons, named LcrH_1 and LcrH_2. However, little is known about chlamydial translocon proteins. In this study, we analyzed CPn0809, one of the putative hydrophobic translocators encoded by the LcrH_1 operon, and identified an 'SseC-like family' domain characteristic of T3S translocators. Using bright-field and confocal microscopy, we found that CPn0809 is associated with EBs during early and very late phases of a C. pneumoniae infection. Furthermore, CPn0809 forms oligomers, and interacts with the T3SS chaperone LcrH_1, via its N-terminal segment. Moreover, expression of full-length CPn0809 in the heterologous host Escherichia coli causes a grave cytotoxic effect that leads to cell death. Taken together, our data indicate that CPn0809 likely represents one of the translocon proteins of the C. pneumoniae T3SS, and possibly plays a role in the translocation of effector proteins in the early stages of infection.
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Affiliation(s)
- Astrid C. Engel
- Lehrstuhl für Funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Frauke Herbst
- Lehrstuhl für Funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Anne Kerres
- Lehrstuhl für Funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Jan N. Galle
- Lehrstuhl für Funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Johannes H. Hegemann
- Lehrstuhl für Funktionelle Genomforschung der Mikroorganismen, Heinrich-Heine-Universität, Düsseldorf, Germany
- * E-mail:
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249
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Morado DR, Hu B, Liu J. Using Tomoauto: A Protocol for High-throughput Automated Cryo-electron Tomography. J Vis Exp 2016:e53608. [PMID: 26863591 DOI: 10.3791/53608] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cryo-electron tomography (Cryo-ET) is a powerful three-dimensional (3-D) imaging technique for visualizing macromolecular complexes in their native context at a molecular level. The technique involves initially preserving the sample in its native state by rapidly freezing the specimen in vitreous ice, then collecting a series of micrographs from different angles at high magnification, and finally computationally reconstructing a 3-D density map. The frozen-hydrated specimen is extremely sensitive to the electron beam and so micrographs are collected at very low electron doses to limit the radiation damage. As a result, the raw cryo-tomogram has a very low signal to noise ratio characterized by an intrinsically noisy image. To better visualize subjects of interest, conventional imaging analysis and sub-tomogram averaging in which sub-tomograms of the subject are extracted from the initial tomogram and aligned and averaged are utilized to improve both contrast and resolution. Large datasets of tilt-series are essential to understanding and resolving the complexes at different states, conditions, or mutations as well as obtaining a large enough collection of sub-tomograms for averaging and classification. Collecting and processing this data can be a major obstacle preventing further analysis. Here we describe a high-throughput cryo-ET protocol based on a computer-controlled 300kV cryo-electron microscope, a direct detection device (DDD) camera and a highly effective, semi-automated image-processing pipeline software wrapper library tomoauto developed in-house. This protocol has been effectively utilized to visualize the intact type III secretion system (T3SS) in Shigella flexneri minicells. It can be applicable to any project suitable for cryo-ET.
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Affiliation(s)
- Dustin R Morado
- Department of Pathology and Laboratory Medicine, University of Texas Health Science Center at Houston
| | - Bo Hu
- Department of Pathology and Laboratory Medicine, University of Texas Health Science Center at Houston
| | - Jun Liu
- Department of Pathology and Laboratory Medicine, University of Texas Health Science Center at Houston;
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Romano FB, Tang Y, Rossi KC, Monopoli KR, Ross JL, Heuck AP. Type 3 Secretion Translocators Spontaneously Assemble a Hexadecameric Transmembrane Complex. J Biol Chem 2016; 291:6304-15. [PMID: 26786106 DOI: 10.1074/jbc.m115.681031] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Indexed: 11/06/2022] Open
Abstract
A type 3 secretion system is used by many bacterial pathogens to inject proteins into eukaryotic cells. Pathogens insert a translocon complex into the target eukaryotic membrane by secreting two proteins known as translocators. How these translocators form a translocon in the lipid bilayer and why both proteins are required remains elusive. Pseudomonas aeruginosa translocators PopB and PopD insert pores into membranes forming homo- or hetero-complexes of undetermined stoichiometry. Single-molecule fluorescence photobleaching experiments revealed that PopD formed mostly hexameric structures in membranes, whereas PopB displayed a bi-modal distribution with 6 and 12 subunits peaks. However, individually the proteins are not functional for effector translocation. We have found that when added together, the translocators formed distinct hetero-complexes containing 8 PopB and 8 PopD molecules. Thus, the interaction between PopB and PopD guide the assembly of a unique hetero-oligomer in membranes.
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Affiliation(s)
| | - Yuzhou Tang
- From the Program in Molecular and Cellular Biology, and
| | - Kyle C Rossi
- the Departments of Biochemistry and Molecular Biology and
| | | | - Jennifer L Ross
- From the Program in Molecular and Cellular Biology, and Physics, University of Massachusetts, Amherst, Massachusetts 01003
| | - Alejandro P Heuck
- From the Program in Molecular and Cellular Biology, and the Departments of Biochemistry and Molecular Biology and
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