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Liu L, Yu W, Cai K, Ma S, Wang Y, Ma Y, Zhao H. Identification of vaccine candidates against rhodococcus equi by combining pangenome analysis with a reverse vaccinology approach. Heliyon 2023; 9:e18623. [PMID: 37576287 PMCID: PMC10413060 DOI: 10.1016/j.heliyon.2023.e18623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/12/2023] [Accepted: 07/24/2023] [Indexed: 08/15/2023] Open
Abstract
Rhodococcus equi (R. equi) is a zoonotic opportunistic pathogen that can cause life-threatening infections. The rapid evolution of multidrug-resistant R. equi and the fact that there is no currently licensed effective vaccine against R. equi warrant the need for vaccine development. Reverse vaccinology (RV), which involves screening a pathogen's entire genome and proteome using various web-based prediction tools, is considered one of the most effective approaches for identifying vaccine candidates. Here, we performed a pangenome analysis to determine the core proteins of R. equi. We then used the RV approach to examine the subcellular localization, host and gut flora homology, antigenicity, transmembrane helices, physicochemical properties, and immunogenicity of the core proteins to select potential vaccine candidates. The vaccine candidates were then subjected to epitope mapping to predict the exposed antigenic epitopes that possess the ability to bind with major histocompatibility complex I/II (MHC I/II) molecules. These vaccine candidates and epitopes will form a library of elements for the development of a polyvalent or universal vaccine against R. equi. Sixteen R. equi complete proteomes were found to contain 6,238 protein families, and the core proteins consisted of 3,969 protein families (∼63.63% of the pangenome), reflecting a low degree of intraspecies genomic variability. From the pool of core proteins, 483 nonhost homologous membrane and extracellular proteins were screened, and 12 vaccine candidates were finally identified according to their antigenicity, physicochemical properties and other factors. These included four cell wall/membrane/envelope biogenesis proteins; four amino acid transport and metabolism proteins; one cell cycle control, cell division and chromosome partitioning protein; one carbohydrate transport and metabolism protein; one secondary metabolite biosynthesis, transport and catabolism protein; and one defense mechanism protein. All 12 vaccine candidates have an experimentally validated 3D structure available in the protein data bank (PDB). Epitope mapping of the candidates showed that 16 MHC I epitopes and 13 MHC II epitopes with the strongest immunogenicity were exposed on the protein surface, indicating that they could be used to develop a polypeptide vaccine. Thus, we utilized an analytical strategy that combines pangenome analysis and RV to generate a peptide antigen library that simplifies the development of multivalent or universal vaccines against R. equi and can be applied to the development of other vaccines.
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Affiliation(s)
- Lu Liu
- College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China
| | - Wanli Yu
- College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China
| | - Kuojun Cai
- College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China
| | - Siyuan Ma
- College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China
| | - Yanfeng Wang
- College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China
| | - Yuhui Ma
- Zhaosu Xiyu Horse Industry Co., Ltd. Zhaosu County 835699, Yili Prefecture, Xinjiang, China
| | - Hongqiong Zhao
- College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China
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Lê-Bury P, Druart K, Savin C, Lechat P, Mas Fiol G, Matondo M, Bécavin C, Dussurget O, Pizarro-Cerdá J. Yersiniomics, a Multi-Omics Interactive Database for Yersinia Species. Microbiol Spectr 2023; 11:e0382622. [PMID: 36847572 PMCID: PMC10100798 DOI: 10.1128/spectrum.03826-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 01/26/2023] [Indexed: 03/01/2023] Open
Abstract
The genus Yersinia includes a large variety of nonpathogenic and life-threatening pathogenic bacteria, which cause a broad spectrum of diseases in humans and animals, such as plague, enteritis, Far East scarlet-like fever (FESLF), and enteric redmouth disease. Like most clinically relevant microorganisms, Yersinia spp. are currently subjected to intense multi-omics investigations whose numbers have increased extensively in recent years, generating massive amounts of data useful for diagnostic and therapeutic developments. The lack of a simple and centralized way to exploit these data led us to design Yersiniomics, a web-based platform allowing straightforward analysis of Yersinia omics data. Yersiniomics contains a curated multi-omics database at its core, gathering 200 genomic, 317 transcriptomic, and 62 proteomic data sets for Yersinia species. It integrates genomic, transcriptomic, and proteomic browsers, a genome viewer, and a heatmap viewer to navigate within genomes and experimental conditions. For streamlined access to structural and functional properties, it directly links each gene to GenBank, the Kyoto Encyclopedia of Genes and Genomes (KEGG), UniProt, InterPro, IntAct, and the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and each experiment to Gene Expression Omnibus (GEO), the European Nucleotide Archive (ENA), or the Proteomics Identifications Database (PRIDE). Yersiniomics provides a powerful tool for microbiologists to assist with investigations ranging from specific gene studies to systems biology studies. IMPORTANCE The expanding genus Yersinia is composed of multiple nonpathogenic species and a few pathogenic species, including the deadly etiologic agent of plague, Yersinia pestis. In 2 decades, the number of genomic, transcriptomic, and proteomic studies on Yersinia grew massively, delivering a wealth of data. We developed Yersiniomics, an interactive web-based platform, to centralize and analyze omics data sets on Yersinia species. The platform allows user-friendly navigation between genomic data, expression data, and experimental conditions. Yersiniomics will be a valuable tool to microbiologists.
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Affiliation(s)
- Pierre Lê-Bury
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, Paris, France
| | - Karen Druart
- Institut Pasteur, Université Paris Cité, CNRS USR2000, Mass Spectrometry for Biology Unit, Proteomic Platform, Paris, France
| | - Cyril Savin
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, Paris, France
- Institut Pasteur, Université Paris Cité, Yersinia National Reference Laboratory, WHO Collaborating Research & Reference Centre for Plague FRA-140, Paris, France
| | - Pierre Lechat
- Institut Pasteur, Université Paris Cité, ALPS, Bioinformatic Hub, Paris, France
| | - Guillem Mas Fiol
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, Paris, France
| | - Mariette Matondo
- Institut Pasteur, Université Paris Cité, CNRS USR2000, Mass Spectrometry for Biology Unit, Proteomic Platform, Paris, France
| | | | - Olivier Dussurget
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, Paris, France
| | - Javier Pizarro-Cerdá
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Yersinia Research Unit, Paris, France
- Institut Pasteur, Université Paris Cité, Yersinia National Reference Laboratory, WHO Collaborating Research & Reference Centre for Plague FRA-140, Paris, France
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Woodward SE, Vogt SL, Peña-Díaz J, Melnyk RA, Cirstea M, Serapio-Palacios A, Neufeld LMP, Huus KE, Wang MA, Haney CH, Finlay BB. Gastric acid and escape to systemic circulation represent major bottlenecks to host infection by Citrobacter rodentium. THE ISME JOURNAL 2023; 17:36-46. [PMID: 36153406 PMCID: PMC9751147 DOI: 10.1038/s41396-022-01321-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 09/05/2022] [Accepted: 09/08/2022] [Indexed: 11/09/2022]
Abstract
The gastrointestinal (GI) environment plays a critical role in shaping enteric infections. Host environmental factors create bottlenecks, restrictive events that reduce the genetic diversity of invading bacterial populations. However, the identity and impact of bottleneck events on bacterial infection are largely unknown. We used Citrobacter rodentium infection of mice, a model of human pathogenic Escherichia coli infections, to examine bacterial population dynamics and quantify bottlenecks to host colonization. Using Sequence Tag-based Analysis of Microbial Populations (STAMP) we characterized the founding population size (Nb') and relatedness of C. rodentium populations at relevant tissue sites during early- and peak-infection. We demonstrate that the GI environment severely restricts the colonizing population, with an average Nb' of only 12-43 lineages (of 2,000+ inoculated) identified regardless of time or biogeographic location. Passage through gastric acid and escape to the systemic circulation were identified as major bottlenecks during C. rodentium colonization. Manipulating such events by increasing gastric pH dramatically increased intestinal Nb'. Importantly, removal of the stomach acid barrier had downstream consequences on host systemic colonization, morbidity, and mortality. These findings highlight the capability of the host GI environment to limit early pathogen colonization, controlling the population of initial founders with consequences for downstream infection outcomes.
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Affiliation(s)
- Sarah E Woodward
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - Stefanie L Vogt
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - Jorge Peña-Díaz
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - Ryan A Melnyk
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Mihai Cirstea
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | | | - Laurel M P Neufeld
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
| | - Kelsey E Huus
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - Madeline A Wang
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - Cara H Haney
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - B Brett Finlay
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada.
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada.
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
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Phyletic Distribution and Diversification of the Phage Shock Protein Stress Response System in Bacteria and Archaea. mSystems 2022; 7:e0134821. [PMID: 35604119 PMCID: PMC9239133 DOI: 10.1128/msystems.01348-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The PspA protein domain is found in all domains of life, highlighting its central role in Psp networks. To date, all insights into the core functions of Psp responses derive mainly from protein network blueprints representing only three bacterial phyla.
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Skurnik M, Jaakkola S, Mattinen L, von Ossowski L, Nawaz A, Pajunen MI, Happonen LJ. Bacteriophages fEV-1 and fD1 Infect Yersinia pestis. Viruses 2021; 13:1384. [PMID: 34372590 PMCID: PMC8309999 DOI: 10.3390/v13071384] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 07/14/2021] [Accepted: 07/14/2021] [Indexed: 11/17/2022] Open
Abstract
Bacteriophages vB_YpeM_fEV-1 (fEV-1) and vB_YpeM_fD1 (fD1) were isolated from incoming sewage water samples in Turku, Finland, using Yersinia pestis strains EV76 and KIM D27 as enrichment hosts, respectively. Genomic analysis and transmission electron microscopy established that fEV-1 is a novel type of dwarf myovirus, while fD1 is a T4-like myovirus. The genome sizes are 38 and 167 kb, respectively. To date, the morphology and genome sequences of some dwarf myoviruses have been described; however, a proteome characterization such as the one presented here, has currently been lacking for this group of viruses. Notably, fEV-1 is the first dwarf myovirus described for Y. pestis. The host range of fEV-1 was restricted strictly to Y. pestis strains, while that of fD1 also included other members of Enterobacterales such as Escherichia coli and Yersinia pseudotuberculosis. In this study, we present the life cycles, genomes, and proteomes of two Yersinia myoviruses, fEV-1 and fD1.
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Affiliation(s)
- Mikael Skurnik
- Department of Bacteriology and Immunology, Medicum, Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; (S.J.); (L.M.); (A.N.); (M.I.P.)
- Division of Clinical Microbiology, HUSLAB, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, Finland
| | - Salla Jaakkola
- Department of Bacteriology and Immunology, Medicum, Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; (S.J.); (L.M.); (A.N.); (M.I.P.)
| | - Laura Mattinen
- Department of Bacteriology and Immunology, Medicum, Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; (S.J.); (L.M.); (A.N.); (M.I.P.)
| | - Lotta von Ossowski
- Department of Medical Biochemistry, University of Turku, 20520 Turku, Finland;
| | - Ayesha Nawaz
- Department of Bacteriology and Immunology, Medicum, Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; (S.J.); (L.M.); (A.N.); (M.I.P.)
| | - Maria I. Pajunen
- Department of Bacteriology and Immunology, Medicum, Human Microbiome Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland; (S.J.); (L.M.); (A.N.); (M.I.P.)
| | - Lotta J. Happonen
- Division of Infection Medicine, Department of Clinical Sciences Lund, Lund University, 22184 Lund, Sweden;
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Reinseth IS, Ovchinnikov KV, Tønnesen HH, Carlsen H, Diep DB. The Increasing Issue of Vancomycin-Resistant Enterococci and the Bacteriocin Solution. Probiotics Antimicrob Proteins 2021; 12:1203-1217. [PMID: 31758332 PMCID: PMC8613153 DOI: 10.1007/s12602-019-09618-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Enterococci are commensals of human and other animals’ gastrointestinal tracts. Only making up a small part of the microbiota, they have not played a significant role in research, until the 1980s. Although the exact year is variable according to different geographical areas, this was the decade when vancomycin-resistant enterococci (VRE) were discovered and since then their role as causative agents of human infections has increased. Enterococcus faecium is on the WHO’s list of “bacteria for which new antibiotics are urgently needed,” and with no new antibiotics in development, the situation is desperate. In this review, different aspects of VRE are outlined, including the mortality caused by VRE, antibiotic resistance profiles, animal-modeling efforts, and virulence. In addition, the limitations of current antibiotic treatments for VRE and prospective new treatments, such as bacteriocins, are reviewed.
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Affiliation(s)
- Ingvild S Reinseth
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, 1432, Ås, Norway
| | - Kirill V Ovchinnikov
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, 1432, Ås, Norway
| | - Hanne H Tønnesen
- Section of Pharmaceutics and Social Pharmacy, Department of Pharmacy, University of Oslo, P.O. Box 1068 Blindern, 0316, Oslo, Norway
| | - Harald Carlsen
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, 1432, Ås, Norway
| | - Dzung B Diep
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, 1432, Ås, Norway.
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Feng H, Yuan Y, Yang Z, Xing XH, Zhang C. Genome-wide genotype-phenotype associations in microbes. J Biosci Bioeng 2021; 132:1-8. [PMID: 33895083 DOI: 10.1016/j.jbiosc.2021.03.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 03/17/2021] [Accepted: 03/23/2021] [Indexed: 12/24/2022]
Abstract
The concept of a gene has been developed a lot since the Mendelian era owing to the rapid progress in molecular biology and informatics. To explore the nature of life, varieties of biological tools have been continuously established. Many achievements have been made to clarify the relationships between genotypes and phenotypes. However, it is still not completely clear that how traits of an organism are encoded by its genome. In this review, we will summarize and discuss representative works in systematical functional genomic studies in microbes. By analyzing their developmental progressions and limitations, we may have chances to design more powerful means to decipher the code of life.
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Affiliation(s)
- Huibao Feng
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Yaomeng Yuan
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Zheng Yang
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Xin-Hui Xing
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China
| | - Chong Zhang
- MOE Key Laboratory for Industrial Biocatalysis, Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China; Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China.
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8
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Staphylococcus aureus Preferentially Liberates Inorganic Phosphate from Organophosphates in Environments where This Nutrient Is Limiting. J Bacteriol 2020; 202:JB.00264-20. [PMID: 32868400 DOI: 10.1128/jb.00264-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/27/2020] [Indexed: 11/20/2022] Open
Abstract
Phosphate is an essential nutrient that Staphylococcus aureus and other pathogens must acquire from the host during infection. While inorganic monophosphate (Pi) is the preferred source of this nutrient, bacteria can also obtain it from phosphate-containing organic molecules. The Pi-responsive regulator PhoPR is necessary for S. aureus to cause infection, suggesting that Pi is not freely available during infection and that this nutrient must be obtained from other sources. However, the organophosphates from which S. aureus can obtain phosphate are unknown. We evaluated the ability of 58 phosphorus-containing molecules to serve as phosphate sources for S. aureus Forty-six of these compounds, including phosphorylated amino acids, sugars, and nucleotides, supported growth. Among the organophosphate sources was glycerol-3-phosphate (G3P), which is commonly found in the mammalian host. Differing from the model organism Escherichia coli, S. aureus does not import G3P intact to obtain Pi Instead, S. aureus relies on the phosphatase PhoB to release Pi from G3P, which is subsequently imported by Pi transporters. To determine if this strategy is used by S. aureus to extract phosphate from other phosphate sources, we assessed the ability of PhoB- and Pi transporter-deficient strains to grow on the same library of phosphorus-containing molecules. Sixty percent of the substrates (28/46) relied on the PhoB/Pi transporter pathway, and an additional 10/46 (22%) were PhoB independent but still required Pi transport through the Pi transporters. Cumulatively, these results suggest that in Pi-limited environments, S. aureus preferentially generates Pi from organophosphates and then relies on Pi transporters to import this nutrient.IMPORTANCE For bacteria, the preferred form of the essential nutrient phosphate is inorganic monophosphate (Pi), but phosphate can also be extracted from a variety of phosphocompounds. Pathogens, including Staphylococcus aureus, experience Pi limitation within the host, suggesting that the use of alternative phosphate sources is important during infection. However, the alternative phosphate sources that can be used by S. aureus and others remain largely unexplored. We screened a library of phosphorus-containing compounds for the ability to support growth as a phosphate source. S. aureus could use a variety of phosphocompounds, including nucleotides, phosphosugars, and phosphoamino acids. Subsequent genetic analysis determined that a majority of these alternative phosphate sources are first processed extracellularly to liberate Pi, which is then imported through Pi transporters.
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PhoP-Mediated Repression of the SPI1 Type 3 Secretion System in Salmonella enterica Serovar Typhimurium. J Bacteriol 2019; 201:JB.00264-19. [PMID: 31182495 DOI: 10.1128/jb.00264-19] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 05/31/2019] [Indexed: 12/13/2022] Open
Abstract
Salmonella must rapidly adapt to various niches in the host during infection. Relevant virulence factors must be appropriately induced, and systems that are detrimental in a particular environment must be turned off. Salmonella infects intestinal epithelial cells using a type 3 secretion system (T3SS) encoded on Salmonella pathogenicity island 1 (SPI1). The system is controlled by three AraC-like regulators, HilD, HilC, and RtsA, which form a complex feed-forward loop to activate expression of hilA, encoding the main transcriptional regulator of T3SS structural genes. This system is tightly regulated, with many of the activating signals acting at the level of hilD translation or HilD protein activity. Once inside the phagosomes of epithelial cells, or in macrophages during systemic stages of disease, the SPI1 T3SS is no longer required or expressed. Here, we show that the PhoPQ two-component system, critical for intracellular survival, appears to be the primary mechanism by which Salmonella shuts down the SPI1 T3SS. PhoP negatively regulates hilA through multiple distinct mechanisms: direct transcriptional repression of the hilA promoter, indirect transcriptional repression of both the hilD and rtsA promoters, and activation of the small RNA (sRNA) PinT. Genetic analyses and electrophoretic mobility shift assays suggest that PhoP specifically binds the hilA promoter to block binding of activators HilD, HilC, and RtsA as a mechanism of repression.IMPORTANCE Salmonella is one of the most common foodborne pathogens, causing an estimated 1.2 million illnesses per year in the United States. A key step in infection is the activation of the bacterial invasion machinery, which induces uptake of the bacterium into epithelial cells and leads to induction of inflammatory diarrhea. Upon entering the vacuolar compartments of host cells, Salmonella senses an environmental transition and represses the invasion machinery with a two-component system relevant for survival within the vacuole. This adaptation to specific host niches is an important example of how signals are integrated for survival of the pathogen.
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10
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DeAngelis CM, Nag D, Withey JH, Matson JS. Characterization of the Vibrio cholerae Phage Shock Protein Response. J Bacteriol 2019; 201:e00761-18. [PMID: 30858296 PMCID: PMC6597379 DOI: 10.1128/jb.00761-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 02/26/2019] [Indexed: 12/25/2022] Open
Abstract
The phage shock protein (Psp) system is a stress response pathway that senses and responds to inner membrane damage. The genetic components of the Psp system are present in several clinically relevant Gram-negative bacteria, including Vibrio cholerae However, most of the current knowledge about the Psp response stems from in vitro studies in Escherichia coli and Yersinia enterocolitica In fact, the Psp response in V. cholerae has remained completely uncharacterized. In this study, we demonstrate that V. cholerae does have a functional Psp response system. We found that overexpression of GspD (EpsD), the type II secretion system secretin, induces the Psp response, whereas other V. cholerae secretins do not. In addition, we have identified several environmental conditions that induce this stress response. Our studies on the genetic regulation and induction of the Psp system in V. cholerae suggest that the key regulatory elements are conserved with those of other Gram-negative bacteria. While a psp null strain is fully capable of colonizing the infant mouse intestine, it exhibits a colonization defect in a zebrafish model, indicating that this response may be important for disease transmission in the environment. Overall, these studies provide an initial understanding of a stress response pathway that has not been previously investigated in V. choleraeIMPORTANCEVibrio cholerae leads a dual life cycle, as it can exist in the aquatic environment and colonize the human small intestine. In both life cycles, V. cholerae encounters a variety of stressful conditions, including fluctuating pH and temperature and exposure to other agents that may negatively affect cell envelope homeostasis. The phage shock protein (Psp) response is required to sense and respond to such insults in other bacteria but has remained unstudied in V. cholerae Interestingly, the Psp system has protein homologs, principally, PspA, in a number of bacterial clades as well as in archaea and plants. Therefore, our findings not only fill a gap in knowledge about an unstudied extracytoplasmic stress response in V. cholerae, but also may have far-reaching implications.
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Affiliation(s)
- Cara M DeAngelis
- Department of Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
| | - Dhrubajyoti Nag
- Department of Biochemistry, Microbiology, and Immunology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Jeffrey H Withey
- Department of Biochemistry, Microbiology, and Immunology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Jyl S Matson
- Department of Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA
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Huang L, Zuo Y, Jiang Q, Su Y, Qin Y, Xu X, Zhao L, Yan Q. A metabolomic investigation into the temperature-dependent virulence of Pseudomonas plecoglossicida from large yellow croaker (Pseudosciaena crocea). JOURNAL OF FISH DISEASES 2019; 42:431-446. [PMID: 30659613 DOI: 10.1111/jfd.12957] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 12/18/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
Abstract
Pseudomonas plecoglossicida is associated with multiple fish diseases, and temperature is one of the most important environmental factors related to its outbreak. To elucidate the influence of temperature variation on the pathogen, the global metabolomics of P. plecoglossicida (NZBD9) were analysed at the virulent (18°C) and avirulent (12°C and 28°C) temperatures. The result showed that the levels of Phosphoric acid, Tyrosine, Spermidine and Sucrose were significantly reduced,while Itaconic acid, Glucaric acid and Isomaltose were increased in P. plecoglossicida at 18°C. These metabolic adjustments assist P. plecoglossicida to survive in adverse environments, proliferate in the host, colonize and resist host immune clearance during the initial steps of infection. The results suggested that L321_03626 and L321_18122 genes played a key role in the regulation of these metabolic adaptions and thus regulated P. plecoglossicida virulence at virulent temperature, which was proved by further gene silencing and artificial infection. The present study, for the first time, determines the P. plecoglossicida metabolomic responses to temperature variation, which is helpful to explore its pathogenic mechanism and provides reference for disease control.
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Affiliation(s)
- Lixing Huang
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Yanfei Zuo
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Qingling Jiang
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Yongquan Su
- State Key Laboratory of Large Yellow Croaker Breeding, Ningde, China
| | - Yingxue Qin
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Xiaojin Xu
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Lingmin Zhao
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Qingpi Yan
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
- State Key Laboratory of Large Yellow Croaker Breeding, Ningde, China
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12
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PhoPR Contributes to Staphylococcus aureus Growth during Phosphate Starvation and Pathogenesis in an Environment-Specific Manner. Infect Immun 2018; 86:IAI.00371-18. [PMID: 30061377 DOI: 10.1128/iai.00371-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/21/2018] [Indexed: 12/31/2022] Open
Abstract
Microbial pathogens must obtain all essential nutrients, including phosphate, from the host. To optimize phosphate acquisition in diverse and dynamic environments, such as mammalian tissues, many bacteria use the PhoPR two-component system. Despite the necessity of this system for virulence in several species, PhoPR has not been studied in the major human pathogen Staphylococcus aureus To illuminate its role in staphylococcal physiology, we initially assessed whether PhoPR controls the expression of the three inorganic phosphate (Pi) importers (PstSCAB, NptA, and PitA) in S. aureus This analysis revealed that PhoPR is required for the expression of pstSCAB and nptA and can modulate pitA expression. Consistent with a role in phosphate homeostasis, PhoPR-mediated regulation of the transporters is influenced by phosphate availability. Further investigations revealed that PhoPR is necessary for growth under Pi-limiting conditions, and in some environments, its primary role is to induce the expression of pstSCAB or nptA Interestingly, in other environments, PhoPR is necessary for growth independent of Pi transporter expression, indicating that additional PhoPR-regulated factors promote S. aureus adaptation to low-Pi conditions. Together, these data suggest that PhoPR differentially contributes to growth in an environment-specific manner. In a systemic infection model, a mutant of S. aureus lacking PhoPR is highly attenuated. Further investigation revealed that PhoPR-regulated factors, in addition to Pi transporters, are critical for staphylococcal pathogenesis. Cumulatively, these findings point to an important role for PhoPR in orchestrating Pi acquisition as well as transporter-independent mechanisms that contribute to S. aureus virulence.
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13
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Ahmad S, Raza S, Qurat-ul-Ain, Uddin R, Rungrotmongkol T, Azam SS. From phylogeny to protein dynamics: A computational hierarchical quest for potent drug identification against an emerging enteropathogen “Yersinia enterocolitica”. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.06.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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14
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Clarke BR, Ovchinnikova OG, Kelly SD, Williamson ML, Butler JE, Liu B, Wang L, Gou X, Follador R, Lowary TL, Whitfield C. Molecular basis for the structural diversity in serogroup O2-antigen polysaccharides in Klebsiella pneumoniae. J Biol Chem 2018; 293:4666-4679. [PMID: 29602878 DOI: 10.1074/jbc.ra117.000646] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 01/23/2018] [Indexed: 12/17/2022] Open
Abstract
Klebsiella pneumoniae is a major health threat. Vaccination and passive immunization are considered as alternative therapeutic strategies for managing Klebsiella infections. Lipopolysaccharide O antigens are attractive candidates because of the relatively small range of known O-antigen polysaccharide structures, but immunotherapeutic applications require a complete understanding of the structures found in clinical settings. Currently, the precise number of Klebsiella O antigens is unknown because available serological tests have limited resolution, and their association with defined chemical structures is sometimes uncertain. Molecular serotyping methods can evaluate clinical prevalence of O serotypes but require a full understanding of the genetic determinants for each O-antigen structure. This is problematic with Klebsiella pneumoniae because genes outside the main rfb (O-antigen biosynthesis) locus can have profound effects on the final structure. Here, we report two new loci encoding enzymes that modify a conserved polysaccharide backbone comprising disaccharide repeat units [→3)-α-d-Galp-(1→3)-β-d-Galf-(1→] (O2a antigen). We identified in serotype O2aeh a three-component system that modifies completed O2a glycan in the periplasm by adding 1,2-linked α-Galp side-group residues. In serotype O2ac, a polysaccharide comprising disaccharide repeat units [→5)-β-d-Galf-(1→3)-β-d-GlcpNAc-(1→] (O2c antigen) is attached to the non-reducing termini of O2a-antigen chains. O2c-polysaccharide synthesis is dependent on a locus encoding three glycosyltransferase enzymes. The authentic O2aeh and O2c antigens were recapitulated in recombinant Escherichia coli hosts to establish the essential gene set for their synthesis. These findings now provide a complete understanding of the molecular genetic basis for the known variations in Klebsiella O-antigen carbohydrate structures based on the O2a backbone.
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Affiliation(s)
- Bradley R Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Olga G Ovchinnikova
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Monica L Williamson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Jennifer E Butler
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda St. TEDA, Tianjin 300457, China
| | - Lu Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda St. TEDA, Tianjin 300457, China
| | - Xi Gou
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda St. TEDA, Tianjin 300457, China
| | | | - Todd L Lowary
- Department of Chemistry and Alberta Glycomics Centre, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
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15
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CUI XIAOWEN, SHERMAN WEN HSUMING, KINOSHITA YOSHIMASA, KOISHI SHOTA, ISOWAKI CHIKA, OU LIUSHU, MASUDA YOSHIMITSU, HONJOH KENICHI, MIYAMOTO TAKAHISA. Role of Phage Shock Protein in Recovery of Heat-injured Salmonella. Biocontrol Sci 2018; 23:17-25. [DOI: 10.4265/bio.23.17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Affiliation(s)
- XIAOWEN CUI
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
| | - HSU-MING SHERMAN WEN
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
| | - YOSHIMASA KINOSHITA
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
| | - SHOTA KOISHI
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
| | - CHIKA ISOWAKI
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
| | - LIUSHU OU
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
| | - YOSHIMITSU MASUDA
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
| | - KEN-ICHI HONJOH
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
| | - TAKAHISA MIYAMOTO
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University
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Acquisition of the Phosphate Transporter NptA Enhances Staphylococcus aureus Pathogenesis by Improving Phosphate Uptake in Divergent Environments. Infect Immun 2017; 86:IAI.00631-17. [PMID: 29084897 DOI: 10.1128/iai.00631-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 10/24/2017] [Indexed: 12/28/2022] Open
Abstract
During infection, pathogens must obtain all inorganic nutrients, such as phosphate, from the host. Despite the essentiality of phosphate for all forms of life, how Staphylococcus aureus obtains this nutrient during infection is unknown. Differing from Escherichia coli, the paradigm for bacterial phosphate acquisition, which has two inorganic phosphate (Pi) importers, genomic analysis suggested that S. aureus possesses three distinct Pi transporters: PstSCAB, PitA, and NptA. While pitA and nptA are expressed in phosphate-replete media, expression of all three transporters is induced by phosphate limitation. The loss of a single transporter did not affect S. aureus However, disruption of any two systems significantly reduced Pi accumulation and growth in divergent environments. These findings indicate that PstSCAB, PitA, and NptA have overlapping but nonredundant functions, thus expanding the environments in which S. aureus can successfully obtain Pi Consistent with this idea, in a systemic mouse model of disease, loss of any one transporter did not decrease staphylococcal virulence. However, loss of NptA in conjunction with either PstSCAB or PitA significantly reduced the ability of S. aureus to cause infection. These observations suggest that Pi acquisition via NptA is particularly important for the pathogenesis of S. aureus While our analysis suggests that NptA homologs are widely distributed among bacteria, closely related less pathogenic staphylococcal species do not possess this importer. Altogether, these observations indicate that Pi uptake by S. aureus differs from established models and that acquisition of a third transporter enhances the ability of the bacterium to cause infection.
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Morgan JM, Duncan MC, Johnson KS, Diepold A, Lam H, Dupzyk AJ, Martin LR, Wong WR, Armitage JP, Linington RG, Auerbuch V. Piericidin A1 Blocks Yersinia Ysc Type III Secretion System Needle Assembly. mSphere 2017; 2:e00030-17. [PMID: 28217742 PMCID: PMC5311113 DOI: 10.1128/msphere.00030-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 01/23/2017] [Indexed: 11/20/2022] Open
Abstract
The type III secretion system (T3SS) is a bacterial virulence factor expressed by dozens of Gram-negative pathogens but largely absent from commensals. The T3SS is an attractive target for antimicrobial agents that may disarm pathogenic bacteria while leaving commensal populations intact. We previously identified piericidin A1 as an inhibitor of the Ysc T3SS in Yersinia pseudotuberculosis. Piericidins were first discovered as inhibitors of complex I of the electron transport chain in mitochondria and some bacteria. However, we found that piericidin A1 did not alter Yersinia membrane potential or inhibit flagellar motility powered by the proton motive force, indicating that the piericidin mode of action against Yersinia type III secretion is independent of complex I. Instead, piericidin A1 reduced the number of T3SS needle complexes visible by fluorescence microscopy at the bacterial surface, preventing T3SS translocator and effector protein secretion. Furthermore, piericidin A1 decreased the abundance of higher-order YscF needle subunit complexes, suggesting that piericidin A1 blocks YscF needle assembly. While expression of T3SS components in Yersinia are positively regulated by active type III secretion, the block in secretion by piericidin A1 was not accompanied by a decrease in T3SS gene expression, indicating that piericidin A1 may target a T3SS regulatory circuit. However, piericidin A1 still inhibited effector protein secretion in the absence of the T3SS regulator YopK, YopD, or YopN. Surprisingly, while piericidin A1 also inhibited the Y. enterocolitica Ysc T3SS, it did not inhibit the SPI-1 family Ysa T3SS in Y. enterocolitica or the Ysc family T3SS in Pseudomonas aeruginosa. Together, these data indicate that piericidin A1 specifically inhibits Yersinia Ysc T3SS needle assembly. IMPORTANCE The bacterial type III secretion system (T3SS) is widely used by both human and animal pathogens to cause disease yet remains incompletely understood. Deciphering how some natural products, such as the microbial metabolite piericidin, inhibit type III secretion can provide important insight into how the T3SS functions or is regulated. Taking this approach, we investigated the ability of piericidin to block T3SS function in several human pathogens. Surprisingly, piericidin selectively inhibited the Ysc family T3SS in enteropathogenic Yersinia but did not affect the function of a different T3SS within the same species. Furthermore, piericidin specifically blocked the formation of T3SS needles on the bacterial surface without altering the localization of several other T3SS components or regulation of T3SS gene expression. These data show that piericidin targets a mechanism important for needle assembly that is unique to the Yersinia Ysc T3SS.
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Affiliation(s)
- Jessica M. Morgan
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California, USA
| | - Miles C. Duncan
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Kevin S. Johnson
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Andreas Diepold
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Hanh Lam
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California, USA
| | - Allison J. Dupzyk
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Lexi R. Martin
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, USA
| | - Weng Ruh Wong
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California, USA
| | - Judith P. Armitage
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Roger G. Linington
- Department of Chemistry and Biochemistry, University of California Santa Cruz, Santa Cruz, California, USA
| | - Victoria Auerbuch
- Department of Microbiology and Environmental Toxicology, University of California Santa Cruz, Santa Cruz, California, USA
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Interactions between the Cytoplasmic Domains of PspB and PspC Silence the Yersinia enterocolitica Phage Shock Protein Response. J Bacteriol 2016; 198:3367-3378. [PMID: 27698088 DOI: 10.1128/jb.00655-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 09/30/2016] [Indexed: 01/24/2023] Open
Abstract
The phage shock protein (Psp) system is a widely conserved cell envelope stress response that is essential for the virulence of some bacteria, including Yersinia enterocolitica Recruitment of PspA by the inner membrane PspB-PspC complex characterizes the activated state of this response. The PspB-PspC complex has been proposed to be a stress-responsive switch, changing from an OFF to an ON state in response to an inducing stimulus. In the OFF state, PspA cannot access its binding site in the C-terminal cytoplasmic domain of PspC (PspCCT), because this site is bound to PspB. PspC has another cytoplasmic domain at its N-terminal end (PspCNT), which has been thought to play a role in maintaining the OFF state, because its removal causes constitutive activation. However, until now, this role has proved recalcitrant to experimental investigation. Here, we developed a combination of approaches to investigate the role of PspCNT in Y. enterocolitica Pulldown assays provided evidence that PspCNT mediates the interaction of PspC with the C-terminal cytoplasmic domain of PspB (PspBCT) in vitro Furthermore, site-specific oxidative cross-linking suggested that a PspCNT-PspBCT interaction occurs only under noninducing conditions in vivo Additional experiments indicated that mutations in pspC might cause constitutive activation by compromising this PspCNT binding site or by causing a conformational disturbance that repositions PspCNT in vivo These findings have provided the first insight into the regulatory function of the N-terminal cytoplasmic domain of PspC, revealing that its ability to participate in an inhibitory complex is essential to silencing the Psp response. IMPORTANCE The phage shock protein (Psp) response has generated widespread interest because it is linked to important phenotypes, including antibiotic resistance, biofilm formation, and virulence in a diverse group of bacteria. Therefore, achieving a comprehensive understanding of how this response is controlled at the molecular level has obvious significance. An integral inner membrane protein complex is believed to be a critical regulatory component that acts as a stress-responsive switch, but some essential characteristics of the switch states are poorly understood. This study provides an important advance by uncovering a new protein interaction domain within this membrane protein complex that is essential to silencing the Psp response in the absence of an inducing stimulus.
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19
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Green ER, Clark S, Crimmins GT, Mack M, Kumamoto CA, Mecsas J. Fis Is Essential for Yersinia pseudotuberculosis Virulence and Protects against Reactive Oxygen Species Produced by Phagocytic Cells during Infection. PLoS Pathog 2016; 12:e1005898. [PMID: 27689357 PMCID: PMC5045184 DOI: 10.1371/journal.ppat.1005898] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/26/2016] [Indexed: 12/17/2022] Open
Abstract
All three pathogenic Yersinia species share a conserved virulence plasmid that encodes a Type 3 Secretion System (T3SS) and its associated effector proteins. During mammalian infection, these effectors are injected into innate immune cells, where they block many bactericidal functions, including the production of reactive oxygen species (ROS). However, Y. pseudotuberculosis (Yptb) lacking the T3SS retains the ability to colonize host organs, demonstrating that chromosome-encoded factors are sufficient for growth within mammalian tissue sites. Previously we uncovered more than 30 chromosomal factors that contribute to growth of T3SS-deficient Yptb in livers. Here, a deep sequencing-based approach was used to validate and characterize the phenotype of 18 of these genes during infection by both WT and plasmid-deficient Yptb. Additionally, the fitness of these mutants was evaluated in immunocompromised mice to determine whether any genes contributed to defense against phagocytic cell restriction. Mutants containing deletions of the dusB-fis operon, which encodes the nucleoid associated protein Fis, were markedly attenuated in immunocompetent mice, but were restored for growth in mice lacking neutrophils and inflammatory monocytes, two of the major cell types responsible for restricting Yersinia infection. We determined that Fis was dispensable for secretion of T3SS effectors, but was essential for resisting ROS and regulated the transcription of several ROS-responsive genes. Strikingly, this protection was critical for virulence, as growth of ΔdusB-fis was restored in mice unable to produce ROS. These data support a model in which ROS generated by neutrophils and inflammatory monocytes that have not been translocated with T3SS effectors enter bacterial cells during infection, where their bactericidal effects are resisted in a Fis-dependent manner. This is the first report of the requirement for Fis during Yersinia infection and also highlights a novel mechanism by which Yptb defends against ROS in mammalian tissues. The pathogenic members of the genus Yersinia share a conserved virulence plasmid that primarily serves to encode a Type 3 Secretion System and its associated effector proteins. During mammalian infection, these effectors are targeted toward phagocytic cells, where they neutralize a multitude of functions, including oxidative burst. However, it has previously been reported that strains of Yersinia pseudotuberculosis lacking the virulence plasmid retain the ability to grow in mammalian tissue sites, suggesting that the Yersinia chromosome encodes a number of poorly appreciated factors that enable survival in mammalian tissue sites, even in the absence of a functional T3SS. Here, we further characterize a number of these factors, including the operon dusB-fis. Using a variety of in vitro and vivo approaches, we determined that Fis regulates the transcription of several genes implicated in ROS resistance and that dusB-fis is essential for preventing growth restriction by ROS produced by the NADPH complex of phagocytes, even in a T3SS-expressing strain. Combined, these data suggest a model in which, during tissue infection, Yersinia evade killing by ROS through both T3SS-dependent and independent mechanisms.
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Affiliation(s)
- Erin R. Green
- Graduate Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Stacie Clark
- Graduate Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Gregory T. Crimmins
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Matthias Mack
- Universitatsklinikum Regensburg, Innere Medizin II/Nephrologie-Transplantation, Regensburg, Germany
| | - Carol A. Kumamoto
- Graduate Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Joan Mecsas
- Graduate Program in Molecular Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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20
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Collery MM, Kuehne SA, McBride SM, Kelly ML, Monot M, Cockayne A, Dupuy B, Minton NP. What's a SNP between friends: The influence of single nucleotide polymorphisms on virulence and phenotypes of Clostridium difficile strain 630 and derivatives. Virulence 2016; 8:767-781. [PMID: 27652799 PMCID: PMC5626343 DOI: 10.1080/21505594.2016.1237333] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Clostridium difficile is a major cause of antibiotic induced diarrhea worldwide, responsible for significant annual mortalities and represents a considerable economic burden on healthcare systems. The two main C. difficile virulence factors are toxins A and B. Isogenic toxin B mutants of 2 independently isolated erythromycin-sensitive derivatives (630E and 630Δerm) of strain 630 were previously shown to exhibit substantively different phenotypes. Compared to 630, strain 630E and its progeny grow slower, achieve lower final cell densities, exhibit a reduced capacity for spore-formation, produce lower levels of toxin and are less virulent in the hamster infection model. By the same measures, strain 630Δerm and its derivatives more closely mirror the behavior of 630. Genome sequencing revealed that 630Δerm had acquired 7 unique Single Nucleotide Polymorphisms (SNPs) compared to 630 and 630E, while 630E had 9 SNPs and a DNA inversion not found in the other 2 strains. The relatively large number of mutations meant that the identification of those responsible for the altered properties of 630E was not possible, despite the restoration of 3 mutations to wildtype by allelic exchange and comparative RNAseq analysis of all 3 strains. The latter analysis revealed large differences in gene expression between the 3 strains, explaining in part why no single SNP could restore the phenotypic differences. Our findings suggest that strain 630Δerm should be favored over 630E as a surrogate for 630 in genetic-based studies. They also underline the importance of effective strain curation and the need to genome re-sequence master seed banks wherever possible.
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Affiliation(s)
- Mark M Collery
- a Clostridia Research Group , BBSRC/EPSRC Synthetic Biology Research Center (SBRC), School of Life Sciences, University of Nottingham , Nottingham , UK
| | - Sarah A Kuehne
- a Clostridia Research Group , BBSRC/EPSRC Synthetic Biology Research Center (SBRC), School of Life Sciences, University of Nottingham , Nottingham , UK.,b NIHR Biomedical Research Unit in Gastrointestinal and Liver Diseases at Nottingham University Hospitals NHS Trust , University of Nottingham , Nottingham , UK
| | - Shonna M McBride
- c Department of Microbiology and Immunology , Emory Antibiotic Resistance Center, Emory University , Atlanta , GA , USA
| | - Michelle L Kelly
- a Clostridia Research Group , BBSRC/EPSRC Synthetic Biology Research Center (SBRC), School of Life Sciences, University of Nottingham , Nottingham , UK
| | - Marc Monot
- d Laboratoire Pathogenèse des Bactéries Anaérobies , Institut Pasteur , Paris , France
| | - Alan Cockayne
- a Clostridia Research Group , BBSRC/EPSRC Synthetic Biology Research Center (SBRC), School of Life Sciences, University of Nottingham , Nottingham , UK
| | - Bruno Dupuy
- d Laboratoire Pathogenèse des Bactéries Anaérobies , Institut Pasteur , Paris , France
| | - Nigel P Minton
- a Clostridia Research Group , BBSRC/EPSRC Synthetic Biology Research Center (SBRC), School of Life Sciences, University of Nottingham , Nottingham , UK.,b NIHR Biomedical Research Unit in Gastrointestinal and Liver Diseases at Nottingham University Hospitals NHS Trust , University of Nottingham , Nottingham , UK
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21
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The RNA Chaperone Hfq Is Essential for Virulence and Modulates the Expression of Four Adhesins in Yersinia enterocolitica. Sci Rep 2016; 6:29275. [PMID: 27387855 PMCID: PMC4937351 DOI: 10.1038/srep29275] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 06/16/2016] [Indexed: 12/13/2022] Open
Abstract
In Enterobacteriaceae, the RNA chaperone Hfq mediates the interaction of small RNAs with target mRNAs, thereby modulating transcript stability and translation. This post-transcriptional control helps bacteria adapt quickly to changing environmental conditions. Our previous mutational analysis showed that Hfq is involved in metabolism and stress survival in the enteropathogen Yersinia enterocolitica. In this study we demonstrate that Hfq is essential for virulence in mice and influences production of surface pathogenicity factors, in particular lipopolysaccharide and adhesins mediating interaction with host tissue. Hfq inhibited the production of Ail, the Ail-like protein OmpX and the MyfA pilin post-transcriptionally. In contrast Hfq promoted production of two major autotransporter adhesins YadA and InvA. While protein secretion in vitro was not affected, hfq mutants exhibited decreased protein translocation by the type III secretion system into host cells, consistent with decreased production of YadA and InvA. The influence of Hfq on YadA resulted from a complex interplay of transcriptional, post-transcriptional and likely post-translational effects. Hfq regulated invA by modulating the expression of the transcriptional regulators rovA, phoP and ompR. Therefore, Hfq is a global coordinator of surface virulence determinants in Y. enterocolitica suggesting that it constitutes an attractive target for developing new antimicrobial strategies.
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Abstract
The phage shock protein (Psp) system was identified as a response to phage infection in Escherichia coli, but rather than being a specific response to a phage, it detects and mitigates various problems that could increase inner-membrane (IM) permeability. Interest in the Psp system has increased significantly in recent years due to appreciation that Psp-like proteins are found in all three domains of life and because the bacterial Psp response has been linked to virulence and other important phenotypes. In this article, we summarize our current understanding of what the Psp system detects and how it detects it, how four core Psp proteins form a signal transduction cascade between the IM and the cytoplasm, and current ideas that explain how the Psp response keeps bacterial cells alive. Although recent studies have significantly improved our understanding of this system, it is an understanding that is still far from complete.
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Affiliation(s)
- Josué Flores-Kim
- Department of Microbiology, New York University School of Medicine, New York, NY 10016; ,
| | - Andrew J Darwin
- Department of Microbiology, New York University School of Medicine, New York, NY 10016; ,
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23
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Chen S, Thompson KM, Francis MS. Environmental Regulation of Yersinia Pathophysiology. Front Cell Infect Microbiol 2016; 6:25. [PMID: 26973818 PMCID: PMC4773443 DOI: 10.3389/fcimb.2016.00025] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/15/2016] [Indexed: 12/26/2022] Open
Abstract
Hallmarks of Yersinia pathogenesis include the ability to form biofilms on surfaces, the ability to establish close contact with eukaryotic target cells and the ability to hijack eukaryotic cell signaling and take over control of strategic cellular processes. Many of these virulence traits are already well-described. However, of equal importance is knowledge of both confined and global regulatory networks that collaborate together to dictate spatial and temporal control of virulence gene expression. This review has the purpose to incorporate historical observations with new discoveries to provide molecular insight into how some of these regulatory mechanisms respond rapidly to environmental flux to govern tight control of virulence gene expression by pathogenic Yersinia.
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Affiliation(s)
- Shiyun Chen
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences Wuhan, China
| | - Karl M Thompson
- Department of Microbiology, College of Medicine, Howard University Washington, DC, USA
| | - Matthew S Francis
- Umeå Centre for Microbial Research, Umeå UniversityUmeå, Sweden; Department of Molecular Biology, Umeå UniversityUmeå, Sweden
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24
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Zhang N, Jovanovic G, McDonald C, Ces O, Zhang X, Buck M. Transcription Regulation and Membrane Stress Management in Enterobacterial Pathogens. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 915:207-30. [DOI: 10.1007/978-3-319-32189-9_13] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Zaheer R, Klima CL, McAllister TA. Expeditious screening of candidate proteins for microbial vaccines. J Microbiol Methods 2015; 116:53-9. [PMID: 26149626 DOI: 10.1016/j.mimet.2015.06.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 06/26/2015] [Accepted: 06/27/2015] [Indexed: 11/18/2022]
Abstract
Advancements in high-throughput "omics" technologies have revolutionized the way vaccine candidates are identified. Now every surface expressed protein that an organism produces can be identified in silico and possibly made available for the rapid development of recombinant/subunit vaccines. However, evaluating the antigenicity of a large number of candidate proteins is an immense challenge, typically requiring cloning of several hundred candidates followed by immunogenicity screening. Here we report the development of a rapid, high-throughput method for screening candidate proteins for vaccines. This method involves utilizing a coupled, cell-free transcription-translation system to screen tagged proteins that are captured at the C-termini using appropriate ligand coated wells in 96 well ELISA plates. The template DNA for the cell-free expression is generated by two sequential PCRs and includes gene coding sequences, promoter, terminator, other necessary cis-acting elements and appropriate tag sequences. The process generates expressible candidate proteins containing two different peptide tags at the N- and the C-termini of the protein molecules. Proteins are screened in parallel for their quantity and immunoreactivity with N-terminal tag antibodies and antisera raised against the pathogen of interest, respectively. Normalization against the total detectable bound protein in the control wells allows for the identification of highly immunoreactive candidates. For this study we selected 30 representatives of >300 potential candidate proteins from Mannheimia haemolytica, a bacterial agent of pneumonia in feedlot cattle for expression with N-terminal Strep-II and C-terminal His(x6)-tag and evaluated their relative immunoreactivities using Strep-tactin-HRP and rabbit antisera generated against M. haemolytica. Using this system we were able to swiftly and quantitatively analyze and rank the suitability of proteins to identify potentially viable vaccine candidates, with the majority of the high ranking candidates being associated with virulence and pathogenicity. The system is adaptable to any bacterial target and presents an alternative to conventional laborious cloning, expression and screening procedures.
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Affiliation(s)
- Rahat Zaheer
- Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, AB T1J 4B1 Canada
| | - Cassidy L Klima
- Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, AB T1J 4B1 Canada
| | - Tim A McAllister
- Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, AB T1J 4B1 Canada.
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Identification of YsaP, the Pilotin of the Yersinia enterocolitica Ysa Type III Secretion System. J Bacteriol 2015; 197:2770-9. [PMID: 26078446 DOI: 10.1128/jb.00238-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 06/09/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Secretins are multimeric outer membrane pore-forming proteins found in complex export systems in Gram-negative bacteria. All type III secretion systems (T3SSs) have a secretin, and one of these is the YsaC secretin of the chromosomally encoded Ysa T3SS of Yersinia enterocolitica. In some cases, pilotin proteins, which are outer membrane lipoproteins, are required for their cognate secretins to multimerize and/or localize to the outer membrane. However, if secretin multimers mislocalize to the inner membrane, this can trigger the protective phage shock protein (Psp) stress response. During a screen for mutations that suppress YsaC toxicity to a psp null strain, we isolated several independent mutations predicted to increase expression of the YE3559 gene within the Ysa pathogenicity island. YE3559, which we have named ysaP, is predicted to encode a small outer membrane lipoprotein, and this location was confirmed by membrane fractionation. Elevated ysaP expression increased the steady-state level of YsaC but made it less toxic to a psp null strain, and it also decreased YsaC-dependent induction of psp gene expression. Subsequent experiments showed that YsaP was not required for YsaC multimerization but was required for the multimers to localize to the outer membrane. Consistent with this, a ysaP null mutation compromised protein export by the Ysa T3SS. All these observations suggest that YsaP is the pilotin for the YsaC secretin. This is only the second pilotin to be characterized for Yersinia and one of only a small number of pilotins described for all bacteria. IMPORTANCE Secretins are essential for the virulence of many bacterial pathogens and also play roles in surface attachment, motility, and competence. This has generated considerable interest in understanding how secretins function. However, their fundamental differences from typical outer membrane proteins have raised various questions about secretins, including how they are assembled into outer membrane multimers. Pilotin proteins facilitate the assembly of some secretins, but only a small number of pilotins have been identified, slowing efforts to understand common and distinct features of secretin assembly. This study provides an important advance by identifying a novel member of the pilotin family and also demonstrating a method of pilotin discovery that could be broadly applied.
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High-throughput, signature-tagged mutagenic approach to identify novel virulence factors of Yersinia pestis CO92 in a mouse model of infection. Infect Immun 2015; 83:2065-81. [PMID: 25754198 DOI: 10.1128/iai.02913-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 02/26/2015] [Indexed: 12/18/2022] Open
Abstract
The identification of new virulence factors in Yersinia pestis and understanding their molecular mechanisms during an infection process are necessary in designing a better vaccine or to formulate an appropriate therapeutic intervention. By using a high-throughput, signature-tagged mutagenic approach, we created 5,088 mutants of Y. pestis strain CO92 and screened them in a mouse model of pneumonic plague at a dose equivalent to 5 50% lethal doses (LD50) of wild-type (WT) CO92. From this screen, we obtained 118 clones showing impairment in disseminating to the spleen, based on hybridization of input versus output DNA from mutant pools with 53 unique signature tags. In the subsequent screen, 20/118 mutants exhibited attenuation at 8 LD50 when tested in a mouse model of bubonic plague, with infection by 10/20 of the aforementioned mutants resulting in 40% or higher survival rates at an infectious dose of 40 LD50. Upon sequencing, six of the attenuated mutants were found to carry interruptions in genes encoding hypothetical proteins or proteins with putative functions. Mutants with in-frame deletion mutations of two of the genes identified from the screen, namely, rbsA, which codes for a putative sugar transport system ATP-binding protein, and vasK, a component of the type VI secretion system, were also found to exhibit some attenuation at 11 or 12 LD50 in a mouse model of pneumonic plague. Likewise, among the remaining 18 signature-tagged mutants, 9 were also attenuated (40 to 100%) at 12 LD50 in a pneumonic plague mouse model. Previously, we found that deleting genes encoding Braun lipoprotein (Lpp) and acyltransferase (MsbB), the latter of which modifies lipopolysaccharide function, reduced the virulence of Y. pestis CO92 in mouse models of bubonic and pneumonic plague. Deletion of rbsA and vasK genes from either the Δlpp single or the Δlpp ΔmsbB double mutant augmented the attenuation to provide 90 to 100% survivability to mice in a pneumonic plague model at 20 to 50 LD50. The mice infected with the Δlpp ΔmsbB ΔrbsA triple mutant at 50 LD50 were 90% protected upon subsequent challenge with 12 LD50 of WT CO92, suggesting that this mutant or others carrying combinational deletions of genes identified through our screen could potentially be further tested and developed into a live attenuated plague vaccine(s).
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Yamamoto M, Kashimoto T, Tong P, Xiao J, Sugiyama M, Inoue M, Matsunaga R, Hosohara K, Nakata K, Yokota K, Oguma K, Yamamoto K. Signature-tagged mutagenesis of Vibrio vulnificus. J Vet Med Sci 2015; 77:823-8. [PMID: 25755021 PMCID: PMC4527504 DOI: 10.1292/jvms.14-0655] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Vibrio vulnificus is the causative agent of primary septicemia, wound
infection and gastroenteritis in immunocompromised people. In this study, signature-tagged
mutagenesis (STM) was applied to identify the virulence genes of V.
vulnificus. Using STM, 6,480 mutants in total were constructed and divided into
81 sets (INPUT pools); each mutant in a set was assigned a different tag. Each INPUT pool
was intraperitoneally injected into iron-overloaded mice, and in vivo
surviving mutants were collected from blood samples from the heart (OUTPUT pools). From
the genomic DNA of mixed INPUT or OUTPUT pools, digoxigenin-labeled DNA probes against the
tagged region were prepared and used for dot hybridization. Thirty tentatively attenuated
mutants, which were hybridized clearly with INPUT probes but barely with OUTPUT probes,
were negatively selected. Lethal doses of 11 of the 30 mutants were reduced to more than
1/100; of these, the lethal doses of 2 were reduced to as low as 1/100,000.
Transposon-inserted genes in the 11 attenuated mutants were those for IMP dehydrogenase,
UDP-N-acetylglucosamine-2-epimerase, aspartokinase, phosphoribosylformylglycinamidine
cyclo-ligase, malate Na (+) symporter and hypothetical protein. When mice were immunized
with an attenuated mutant strain into which IMP dehydrogenase had been inserted with a
transposon, they were protected against V. vulnificus infection. In this
study, we demonstrated that the STM method can be used to search for the virulence genes
of V. vulnificus.
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Affiliation(s)
- Mai Yamamoto
- Department of Nutritional Science, Okayama Prefectural University, Soja, Okayama 719-1197, Japan
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Abstract
Bacteria are omnipotent and they can be found everywhere. The study of bacterial pathogens has been happening from olden days to prevent epidemics, food spoilage, losses in agricultural production, and loss of lives. Modern techniques in DNA based species identification are considered. So, there is a need to acquire simple and quick identification technique. Hence, this review article covers the efficacy of DNA barcoding of bacteria. Routine DNA barcoding involves the production of PCR amplicons from particular regions to sequence them and these sequence data are used to identify or “barcode” that organism to make a distinction from other species.
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Bhaduri S, Sheen S, Sommers CH. Radiation resistance and loss of crystal violet binding activity in Yersinia enterocolitica suspended in raw ground pork exposed to gamma radiation and modified atmosphere. J Food Sci 2014; 79:M911-6. [PMID: 24761745 DOI: 10.1111/1750-3841.12413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 01/19/2014] [Indexed: 12/01/2022]
Abstract
UNLABELLED Virulence of many foodborne pathogens is directly linked to genes carried on self-replicating extra-chromosomal elements, which can transfer genetic material, both vertically and horizontally, between bacteria of the same and different species. Pathogenic Yersinia enterocolitica harbors a 70-kb virulence plasmid (pYV) that encodes genes for low calcium response, crystal violet (CV) binding, Congo red uptake, autoagglutination (AA), hydrophobicity (HP), type III secretion channels, host immune suppression factors, and biofilm formation. Ionizing radiation and modified atmosphere packaging (MAP) are used to control foodborne pathogens and meat spoilage. In this study, the effect of gamma radiation and modified atmosphere (air, 100% N2 , 75% N2 : 25% CO2 , 50% N2 : 50% CO2 , 25% N2 : 75% CO2 , 100% CO2 ) were examined by using the CV binding phenotype, for the presence or absence of pYV in Y. enterocolitica, suspended in raw ground pork. All Y. enterocolitica serovars used (O:3, O:8, and O5,27) were more sensitive to radiation as the CO2 concentration increased above 50%. Crystal violet binding following a radiation dose of 1.0 kGy, which reduced the Y. enterocolitica serovars >5 log, was greatest in the presence of air (ca. 8%), but was not affected by N2 or CO2 concentration (ca. 5%). Following release from modified atmosphere after irradiation, the loss of CV binding rose from 5% to 8% immediately following irradiation to >30% after outgrowth at 25 °C for 24 h. These results, using Y. enterocolitica as a model system, indicate that the risk of foodborne illness could be affected by the loss of virulence factors when postprocess intervention technologies are used. PRACTICAL APPLICATION Provides gamma radiation D10 data for inactivation data for Y. enterocolitica irradiated under modified atmosphere and information to risk assessors regarding the difference between pathogen presence versus actual virulence.
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Affiliation(s)
- Saumya Bhaduri
- Molecular Characterization of Foodborne Pathogens Research Unit, U. S. Dept. of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, PA, 19038, USA
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31
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Darwin AJ. Stress relief during host infection: The phage shock protein response supports bacterial virulence in various ways. PLoS Pathog 2013; 9:e1003388. [PMID: 23853578 PMCID: PMC3708866 DOI: 10.1371/journal.ppat.1003388] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Andrew J Darwin
- Department of Microbiology, New York University School of Medicine, New York, New York, United States of America.
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Expression of a Yersinia pseudotuberculosis Type VI Secretion System Is Responsive to Envelope Stresses through the OmpR Transcriptional Activator. PLoS One 2013; 8:e66615. [PMID: 23840509 PMCID: PMC3686713 DOI: 10.1371/journal.pone.0066615] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 05/07/2013] [Indexed: 01/06/2023] Open
Abstract
The Type VI secretion system (T6SS) is a macromolecular complex widespread in Gram-negative bacteria. Although several T6SS are required for virulence towards host models, most are necessary to eliminate competitor bacteria. Other functions, such as resistance to amoeba predation, biofilm formation or adaptation to environmental conditions have also been reported. This multitude of functions is reflected by the large repertoire of regulatory mechanisms shown to control T6SS expression, production or activation. Here, we demonstrate that one T6SS gene cluster encoded within the Yersinia pseudotuberculosis genome, T6SS-4, is regulated by OmpR, the response regulator of the two-component system EnvZ-OmpR. We first identified OmpR in a transposon mutagenesis screen. OmpR does not control the expression of the four other Y. pseudotuberculosis T6SS gene clusters and of an isolated vgrG gene, and responds to osmotic stresses to bind to and activate the T6SS-4 promoter. Finally, we show that T6SS-4 promotes Y. pseudotuberculosis survival in high osmolarity conditions and resistance to deoxycholate.
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Tseng CW, Kanci A, Citti C, Rosengarten R, Chiu CJ, Chen ZH, Geary SJ, Browning GF, Markham PF. MalF is essential for persistence of Mycoplasma gallisepticum in vivo. MICROBIOLOGY-SGM 2013; 159:1459-1470. [PMID: 23657682 DOI: 10.1099/mic.0.067553-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
There is limited understanding of the molecular basis of virulence in the important avian pathogen Mycoplasma gallisepticum. To define genes that may be involved in colonization of chickens, a collection of mutants of the virulent Ap3AS strain of M. gallisepticum were generated by signature-tagged transposon mutagenesis. The collection included mutants with single insertions in the genes encoding the adhesin GapA and the cytadherence-related protein CrmA, and Western blotting confirmed that these mutants did not express these proteins. In two separate in vivo screenings, two GapA-deficient mutants (ST mutants 02-1 and 06-1) were occasionally recovered from birds, suggesting that GapA expression may not always be essential for persistence of strain Ap3AS. CrmA-deficient ST mutant 33-1 colonized birds poorly and had reduced virulence, indicating that CrmA was a significant virulence factor, but was not absolutely essential for colonization. ST mutant 04-1 contained a single transposon insertion in malF, a predicted ABC sugar transport permease, and could not be reisolated even when inoculated by itself into a group of birds, suggesting that expression of MalF was essential for persistence of M. galliseptium strain Ap3AS in infected birds.
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Affiliation(s)
- Chi-Wen Tseng
- Asia-Pacific Centre for Animal Health, Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Anna Kanci
- Asia-Pacific Centre for Animal Health, Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Christine Citti
- Institute of Bacteriology, Mycology and Hygiene, University of Veterinary Medicine, Vienna, A-1210 Vienna, Austria.,INRA, ENVT, UMR 1225, 31076 Toulouse, France
| | - Renate Rosengarten
- Institute of Bacteriology, Mycology and Hygiene, University of Veterinary Medicine, Vienna, A-1210 Vienna, Austria
| | - Chien-Ju Chiu
- Asia-Pacific Centre for Animal Health, Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Zheng-Hong Chen
- Microbiology Department, Basic Medical College, Guiyang Medical University, Guiyang, Guizhou 550004, PR China
| | - Steven J Geary
- Center of Excellence for Vaccine Research, Department of Pathobiology and Veterinary Science, The University of Connecticut, Storrs, Connecticut 06269, USA
| | - Glenn F Browning
- Asia-Pacific Centre for Animal Health, Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Philip F Markham
- Asia-Pacific Centre for Animal Health, Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria 3010, Australia
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Yan Q, Sreedharan A, Wei S, Wang J, Pelz-Stelinski K, Folimonova S, Wang N. Global gene expression changes in Candidatus Liberibacter asiaticus during the transmission in distinct hosts between plant and insect. MOLECULAR PLANT PATHOLOGY 2013; 14:391-404. [PMID: 23336388 PMCID: PMC6638839 DOI: 10.1111/mpp.12015] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Huanglongbing (HLB) or citrus greening disease is a destructive disease of citrus worldwide, which is associated with Candidatus Liberibacter asiaticus. This phloem-limited fastidious pathogen is transmitted by the Asian citrus psyllid, Diaphorina citri, and appears to be an intracellular pathogen that maintains an intimate association with the psyllid or the plant throughout its life cycle. The molecular basis of the interaction of this pathogen with its hosts is not well understood. We hypothesized that, during infection, Ca. L. asiaticus differentially expresses the genes critical for its survival and/or pathogenicity in either host. To test this hypothesis, quantitative reverse transcription-polymerase chain reaction was performed to compare the gene expression of Ca. L. asiaticus in planta and in psyllid. Overall, 381 genes were analysed for their gene expression in planta and in psyllid. Among them, 182 genes were up-regulated in planta compared with in psyllid (P < 0.05), 16 genes were up-regulated in psyllid (P < 0.05) and 183 genes showed no statistically significant difference (P ≥ 0.05) in expression between in planta and in psyllid. Our study indicates that the expression of the Ca. L. asiaticus genes involved in transcriptional regulation, transport system, secretion system, flagella assembly, metabolic pathway and stress resistance are changed significantly in a host-specific manner to adapt to the distinct environments of plant and insect. To our knowledge, this is the first large-scale study to evaluate the differential expression of Ca. L. asiaticus genes in a plant host and its insect vector.
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Affiliation(s)
- Qing Yan
- Department of Microbiology and Cell Science, Citrus Research and Education Center, IFAS, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
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Skredenske JM, Koppolu V, Kolin A, Deng J, Kettle B, Taylor B, Egan SM. Identification of a small-molecule inhibitor of bacterial AraC family activators. ACTA ACUST UNITED AC 2013; 18:588-98. [PMID: 23364515 DOI: 10.1177/1087057112474690] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Protein members of the AraC family of bacterial transcriptional activators have great promise as targets for the development of novel antibacterial agents. Here, we describe an in vivo high-throughput screen to identify inhibitors of the AraC family activator protein RhaS. The screen used two Escherichia coli reporter fusions: one to identify potential RhaS inhibitors and a second to eliminate nonspecific inhibitors from consideration. One compound with excellent selectivity, OSSL_051168, was chosen for further study. OSSL_051168 inhibited in vivo transcription activation by the RhaS DNA-binding domain to the same extent as the full-length protein, indicating that this domain was the target of its inhibition. Growth curves showed that OSSL_051168 did not affect bacterial cell growth at the concentrations used in this study. In vitro DNA-binding assays with purified protein suggest that OSSL_051168 inhibits DNA binding by RhaS. In addition, we found that it inhibits DNA binding by a second AraC family protein, RhaR, which shares 30% amino acid identity with RhaS. OSSL_051168 did not have a significant impact on DNA binding by the non-AraC family proteins CRP and LacI, suggesting that the inhibition is likely specific for RhaS, RhaR, and possibly additional AraC family activator proteins.
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Affiliation(s)
- Jeff M Skredenske
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA
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36
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Flores-Kim J, Darwin AJ. Links between type III secretion and extracytoplasmic stress responses in Yersinia. Front Cell Infect Microbiol 2012; 2:125. [PMID: 23087910 PMCID: PMC3467454 DOI: 10.3389/fcimb.2012.00125] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 09/24/2012] [Indexed: 11/13/2022] Open
Abstract
The cell envelope of pathogenic bacteria is a barrier against host environmental conditions and immunity molecules, as well as the site where many virulence factors are assembled. Extracytoplasmic stress responses (ESRs) have evolved to help maintain its integrity in conditions where it might be compromised. These ESRs also have important links to the production of envelope-associated virulence systems by the bacteria themselves. One such virulence factor is the type III secretion system (T3SS), the first example of which was provided by the pathogenic Yersinia. This article reviews the reported links between four different ESRs and T3SS function in Yersinia. Components of three of these ESRs affect the function and/or regulation of two different T3SSs. The response regulator of the Rcs ESR is involved in positive regulation of the Ysa-Ysp T3SS found in the highly pathogenic 1B biogroup of Y. enterocolitica. Conversely, the response regulator of the Y. pseudotuberculosis Cpx ESR can down-regulate production of the Ysc-Yop T3SS, and at least one other envelope virulence factor (invasin), by direct repression. Also in Y. pseudotuberculosis, there is some evidence suggesting that an intact RpoE ESR might be important for normal Yersinia outer proteins (Yop) production and secretion. Besides these regulatory links between ESRs and T3SSs, perhaps the most striking connection between T3SS function and an ESR is that between the phage shock protein (Psp) and Ysc-Yop systems of Y. enterocolitica. The Psp response does not affect the regulation or function of the Ysc-Yop system. Instead, Ysc-Yop T3SS production induces the Psp system, which then mitigates T3SS-induced envelope stress. Consequently, the Y. enterocolitica Psp system is essential when the Ysc-Yop T3SS is produced.
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Affiliation(s)
- Josué Flores-Kim
- Department of Microbiology, New York University School of Medicine New York, NY, USA
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Identification of MrtAB, an ABC transporter specifically required for Yersinia pseudotuberculosis to colonize the mesenteric lymph nodes. PLoS Pathog 2012; 8:e1002828. [PMID: 22876175 PMCID: PMC3410872 DOI: 10.1371/journal.ppat.1002828] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 06/15/2012] [Indexed: 12/26/2022] Open
Abstract
A highly conserved virulence plasmid encoding a type III secretion system is shared by the three Yersinia species most pathogenic for mammals. Although factors encoded on this plasmid enhance the ability of Yersinia to thrive in their mammalian hosts, the loss of this virulence plasmid does not eliminate growth or survival in host organs. Most notably, yields of viable plasmid-deficient Yersinia pseudotuberculosis (Yptb) are indistinguishable from wild-type Yptb within mesenteric lymph nodes. To identify chromosomal virulence factors that allow for plasmid-independent survival during systemic infection of mice, we generated transposon insertions in plasmid-deficient Yptb, and screened a library having over 20,000 sequence-identified insertions. Among the previously uncharacterized loci, insertions in mrtAB, an operon encoding an ABC family transporter, had the most profound phenotype in a plasmid-deficient background. The absence of MrtAB, however, had no effect on growth in the liver and spleen of a wild type strain having an intact virulence plasmid, but caused a severe defect in colonization of the mesenteric lymph nodes. Although this result is consistent with lack of expression of the type III secretion system by Wt Yptb in the mesenteric lymph nodes, a reporter for YopE indicated that expression of the system was robust. We demonstrate that the ATPase activity of MrtB is required for growth in mice, indicating that transport activity is required for virulence. Indeed, MrtAB appears to function as an efflux pump, as the ATPase activity enhances resistance to ethidium bromide while increasing sensitivity to pyocyanin, consistent with export across the inner membrane.
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38
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Horstman NK, Darwin AJ. Phage shock proteins B and C prevent lethal cytoplasmic membrane permeability in Yersinia enterocolitica. Mol Microbiol 2012; 85:445-60. [PMID: 22646656 DOI: 10.1111/j.1365-2958.2012.08120.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The bacterial phage shock protein (Psp) stress response system is activated by events affecting the cytoplasmic membrane. In response, Psp protein levels increase, including PspA, which has been implicated as the master effector of stress tolerance. Yersinia enterocolitica and related bacteria with a defective Psp system are highly sensitive to the mislocalization of pore-forming secretin proteins. However, why secretins are toxic to psp null strains, whereas some other Psp inducers are not, has not been explained. Furthermore, previous work has led to the confounding and disputable suggestion that PspA is not involved in mitigating secretin toxicity. Here we have established a correlation between the amount of secretin toxicity in a psp null strain and the extent of cytoplasmic membrane permeability to large molecules. This leads to a morphological change resembling cells undergoing plasmolysis. Furthermore, using novel strains with dis-regulated Psp proteins has allowed us to obtain unequivocal evidence that PspA is not required for secretin-stress tolerance. Together, our data suggest that the mechanism by which secretin multimers kill psp null cells is by causing a profound defect in the cytoplasmic membrane permeability barrier. This allows lethal molecular exchange with the environment, which the PspB and PspC proteins can prevent.
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Affiliation(s)
- N Kaye Horstman
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
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Houppert AS, Kwiatkowski E, Glass EM, DeBord KL, Merritt PM, Schneewind O, Marketon MM. Identification of chromosomal genes in Yersinia pestis that influence type III secretion and delivery of Yops into target cells. PLoS One 2012; 7:e34039. [PMID: 22479512 PMCID: PMC3316589 DOI: 10.1371/journal.pone.0034039] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 02/21/2012] [Indexed: 01/05/2023] Open
Abstract
Pathogenic Yersinia species possess a type III secretion system, which is required for the delivery of effector Yop proteins into target cells during infection. Genes encoding the type III secretion machinery, its substrates, and several regulatory proteins all reside on a 70-Kb virulence plasmid. Genes encoded in the chromosome of yersiniae are thought to play important roles in bacterial perception of host environments and in the coordinated activation of the type III secretion pathway. Here, we investigate the contribution of chromosomal genes to the complex regulatory process controlling type III secretion in Yersinia pestis. Using transposon mutagenesis, we identified five chromosomal genes required for expression or secretion of Yops in laboratory media. Four out of the five chromosomal mutants were defective to various extents at injecting Yops into tissue culture cells. Interestingly, we found one mutant that was not able to secrete in vitro but was fully competent for injecting Yops into host cells, suggesting independent mechanisms for activation of the secretion apparatus. When tested in a mouse model of plague disease, three mutants were avirulent, whereas two strains were severely attenuated. Together these results demonstrate the importance of Y. pestis chromosomal genes in the proper function of type III secretion and in the pathogenesis of plague.
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Affiliation(s)
- Andrew S. Houppert
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Elizabeth Kwiatkowski
- Department of Microbiology, University of Chicago, Chicago, Illinois, United States of America
| | - Elizabeth M. Glass
- Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, Illinois, United States of America
| | - Kristin L. DeBord
- Department of Microbiology, University of Chicago, Chicago, Illinois, United States of America
| | - Peter M. Merritt
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, Illinois, United States of America
| | - Melanie M. Marketon
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
- Department of Microbiology, University of Chicago, Chicago, Illinois, United States of America
- * E-mail:
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40
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Yamaguchi S, Darwin AJ. Recent findings about the Yersinia enterocolitica phage shock protein response. J Microbiol 2012; 50:1-7. [PMID: 22367931 DOI: 10.1007/s12275-012-1578-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 11/23/2011] [Indexed: 01/10/2023]
Abstract
The phage shock protein (Psp) system is a conserved extracytoplasmic stress response in bacteria that is essential for virulence of the human pathogen Yersinia enterocolitica. This article summarizes some recent findings about Y. enterocolitica Psp system function. Increased psp gene expression requires the transcription factor PspF, but under non-inducing conditions PspF is inhibited by an interaction with another protein, PspA, in the cytoplasm. A Psp-inducing stimulus causes PspA to relocate to the cytoplasmic membrane, freeing PspF to induce psp gene expression. This PspA relocation requires the integral cytoplasmic membrane proteins, PspB and PspC, which might sense an inducing trigger and sequester PspA by direct interaction. The subsequent induction of psp gene expression increases the PspA concentration, which also allows it to contact the membrane directly, perhaps for its physiological function. Mutational analysis of the PspB and PspC proteins has revealed that they both positively and negatively regulate psp gene expression and has also identified PspC domains associated with each function. We also compare the contrasting physiological roles of the Psp system in the virulence of Y. enterocolitica and Salmonella enterica sv. Typhimurium (S. Typhimurium). In S. Typhimurium, PspA maintains the proton motive force, which provides the energy needed to drive ion importers required for survival within macrophages. In contrast, in the extracellular pathogen Y. enterocolitica, PspB and PspC, but not PspA, are the Psp components needed for virulence. PspBC protect Y. enterocolitica from damage caused by the secretin component of its type 3 secretion system, an essential virulence factor.
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Affiliation(s)
- Saori Yamaguchi
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
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41
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Crimmins GT, Isberg RR. Analyzing microbial disease at high resolution: following the fate of the bacterium during infection. Curr Opin Microbiol 2011; 15:23-7. [PMID: 22143042 DOI: 10.1016/j.mib.2011.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 11/10/2011] [Accepted: 11/14/2011] [Indexed: 10/14/2022]
Abstract
The study of bacterial pathogens has historically been viewed with a wide lens, providing a picture of how bacterial populations act as groups, but with insufficient resolution to see how microorganisms act as individuals. For most bacterial pathogens, we do not know the minimal number of microbes that initiate infection in a particular organ site, the number that spread outside the site of initial colonization, and how many persist over time. Recent studies have begun to shed light on these points, and the development of new techniques has dramatically increased the ability of researchers to interrogate these problems. With new approaches, the field of bacterial pathogenesis is on the verge of understanding the role and fate of individual bacteria during infection.
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42
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Population dynamics and niche distribution of uropathogenic Escherichia coli during acute and chronic urinary tract infection. Infect Immun 2011; 79:4250-9. [PMID: 21807904 DOI: 10.1128/iai.05339-11] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Urinary tract infections (UTIs) have complex dynamics, with uropathogenic Escherichia coli (UPEC), the major causative agent, capable of colonization from the urethra to the kidneys in both extracellular and intracellular niches while also producing chronic persistent infections and frequent recurrent disease. In mouse and human bladders, UPEC invades the superficial epithelium, and some bacteria enter the cytoplasm to rapidly replicate into intracellular bacterial communities (IBCs) comprised of ~10⁴ bacteria each. Through IBC formation, UPEC expands in numbers while subverting aspects of the innate immune response. Within 12 h of murine bladder infection, half of the bacteria are intracellular, with 3 to 700 IBCs formed. Using mixed infections with green fluorescent protein (GFP) and wild-type (WT) UPEC, we discovered that each IBC is clonally derived from a single bacterium. Genetically tagged UPEC and a multiplex PCR assay were employed to investigate the distribution of UPEC throughout urinary tract niches over time. In the first 24 h postinfection (hpi), the fraction of tags dramatically decreased in the bladder and kidney, while the number of CFU increased. The percentage of tags detected at 6 hpi correlated to the number of IBCs produced, which closely matched a calculated multinomial distribution based on IBC clonality. The fraction of tags remaining thereafter depended on UTI outcome, which ranged from resolution of infection with or without quiescent intracellular reservoirs (QIRs) to the development of chronic cystitis as defined by persistent bacteriuria. Significantly more tags remained in mice that developed chronic cystitis, arguing that during the acute stages of infection, a higher number of IBCs precedes chronic cystitis than precedes QIR formation.
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43
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A novel zinc binding system, ZevAB, is critical for survival of nontypeable Haemophilus influenzae in a murine lung infection model. Infect Immun 2011; 79:3366-76. [PMID: 21576338 DOI: 10.1128/iai.05135-11] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nontypeable Haemophilus influenzae (NTHI) is a Gram-negative bacterial pathogen that causes upper and lower respiratory infections. Factors required for pulmonary infection by NTHI are not well understood. Previously, using high-throughput insertion tracking by deep sequencing (HITS), putative lung colonization factors were identified. Also, previous research indicates that secreted disulfide-dependent factors are important for virulence of H. influenzae. In the present study, HITS data were compared with an informatics-based list of putative substrates of the periplasmic oxidoreductase DsbA to find and characterize secreted virulence factors. This analysis resulted in identification of the "zinc binding essential for virulence" (zev) locus consisting of zevA (HI1249) and zevB (HI1248). NTHI mutants of zevA and zevB grew normally in rich medium but were defective for colonization in a mouse lung model. Mutants also exhibited severe growth defects in medium containing EDTA and were rescued by supplementation with zinc. Additionally, purified recombinant ZevA was found to bind to zinc with high affinity. Together, these data demonstrate that zevAB is a novel virulence factor important for zinc utilization of H. influenzae under conditions where zinc is limiting. Furthermore, evidence presented here suggests that zinc limitation is likely an important mechanism for host defense against pathogens during lung infection.
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Gomez JE, Clatworthy A, Hung DT. Probing bacterial pathogenesis with genetics, genomics, and chemical biology: past, present, and future approaches. Crit Rev Biochem Mol Biol 2011; 46:41-66. [PMID: 21250782 DOI: 10.3109/10409238.2010.538663] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Classical genetic approaches for studying bacterial pathogenesis have provided a solid foundation for our current understanding of microbial physiology and the interactions between pathogen and host. During the past decade however, advances in several arenas have expanded the ways in which the biology of pathogens can be studied. This review discussed the impact of these advances on bacterial genetics, including the application of genomics and chemical biology to the study of pathogenesis.
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Affiliation(s)
- James E Gomez
- The Broad Institute of MIT and Harvard, Cambridge, MA, USA
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45
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Yeung A, Cameron DW, Desjardins M, Lee BC. Use of signature-tagged mutagenesis to identify virulence determinants in Haemophilus ducreyi responsible for ulcer formation. J Microbiol Methods 2011; 84:290-8. [DOI: 10.1016/j.mimet.2010.12.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 12/10/2010] [Accepted: 12/13/2010] [Indexed: 11/17/2022]
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46
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What is type VI secretion doing in all those bugs? Trends Microbiol 2010; 18:531-7. [PMID: 20961764 DOI: 10.1016/j.tim.2010.09.001] [Citation(s) in RCA: 172] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 09/07/2010] [Accepted: 09/08/2010] [Indexed: 11/23/2022]
Abstract
The identification of bacterial secretion systems capable of translocating substrates into eukaryotic cells via needle-like appendages has opened fruitful and exciting areas of microbial pathogenesis research. The recent discovery of the type VI secretion system (T6SS) was met with early speculation that it too acts as a 'needle' that pathogens aim at host cells. New reports demonstrate that certain T6SSs are potent mediators of interbacterial interactions. In light of these findings, we examined earlier data indicating its role in pathogenesis. We conclude that although T6S can, in rare instances, directly influence interactions with higher organisms, the broader physiological significance of the system is likely to provide defense against simple eukaryotic cells and other bacteria in the environment. The crucial role of T6S in bacterial interactions, along with its presence in many organisms relevant to disease, suggests that it might be a key determinant in the progression and outcome of certain human polymicrobial infections.
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Karlinsey JE, Maguire ME, Becker LA, Crouch MLV, Fang FC. The phage shock protein PspA facilitates divalent metal transport and is required for virulence of Salmonella enterica sv. Typhimurium. Mol Microbiol 2010; 78:669-85. [PMID: 20807201 DOI: 10.1111/j.1365-2958.2010.07357.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The phage shock protein (Psp) system is induced by extracytoplasmic stress and thought to be important for the maintenance of proton motive force. We investigated the contribution of PspA to Salmonella virulence. A pspA deletion mutation significantly attenuates the virulence of Salmonella enterica serovar Typhimurium following intraperitoneal inoculation of C3H/HeN (Ity(r) ) mice. PspA was found to be specifically required for virulence in mice expressing the natural resistance-associated macrophage protein 1 (Nramp1) (Slc11a1) divalent metal transporter, which restricts microbial growth by limiting the availability of essential divalent metals within the phagosome. Salmonella competes with Nramp1 by expressing multiple metal uptake systems including the Nramp-homologue MntH, the ABC transporter SitABCD and the ZIP family transporter ZupT. PspA was found to facilitate Mn(2+) transport by MntH and SitABCD, as well as Zn(2+) and Mn(2+) transport by ZupT. In vitro uptake of (54) Mn(2+) by MntH and ZupT was reduced in the absence of PspA. Transport-deficient mutants exhibit reduced viability in the absence of PspA when grown under metal-limited conditions. Moreover, the ZupT transporter is required for Salmonella enterica serovar Typhimurium virulence in Nramp1-expressing mice. We propose that PspA promotes Salmonella virulence by maintaining proton motive force, which is required for the function of multiple transporters mediating bacterial divalent metal acquisition during infection.
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Affiliation(s)
- Joyce E Karlinsey
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195, USA
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49
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Trček J, Fuchs TM, Trülzsch K. Analysis of Yersinia enterocolitica invasin expression in vitro and in vivo using a novel luxCDABE reporter system. Microbiology (Reading) 2010; 156:2734-2745. [DOI: 10.1099/mic.0.038240-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A novel luxCDABE plasmid for the analysis of promoter elements by site-specific integration into the genome of Yersinia enterocolitica was constructed. The versatility of this reporter system was demonstrated by comparing the activity of the inv promoter in the Y. enterocolitica high-pathogenic serotype O : 8 (strain WA-314) with that of the low pathogenic serotype O : 9 (strain Y127). The luciferase activity of a transcriptional fusion between the inv promoter of serotype O : 8 and luxCDABE was about fourfold lower than the activity of the respective O : 9 promoter. This correlated with lower invasin production by Y. enterocolitica serotype O : 8 compared with serotypes O : 9, O : 3 and O : 5,27. However, Y. enterocolitica of serotype O : 8 revealed higher invasiveness than serotype O : 9. When both invasins were expressed in trans at similar levels in the Y. enterocolitica O : 8 Δinv background strain, cell invasion assays showed a slightly higher invasiveness of the strain producing Inv(O : 8) than the strain producing Inv(O : 9). We provide experimental evidence that this might be due to a higher binding capacity of Inv(O : 8) for cells expressing β1 integrins compared with Inv(O:9). The Y. enterocolitica O : 8 strain harbouring the P
inv
(O : 8) : : luxCDABE fusion was then successfully used to follow inv expression in a mouse infection model. These experiments showed for the first time that the inv promoter is active in infected living mice, especially in Peyer's patches of the ileum, the caecal lymph follicle, and the lymph nodes, liver and spleen. The production of invasin in the spleen was demonstrated by Western blot analysis. In conclusion, the presented reporter system enables stable genomic integration of the luxCDABE operon into the chromosome of Yersinia, facilitates in vitro quantification of promoter activities under different bacterial growth conditions, and enables detection of promoter activities in a mouse model.
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Affiliation(s)
- Janja Trček
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität, München, Germany
| | - Thilo M. Fuchs
- Zentralinstitut für Ernährung- und Lebensmittelforschung, Abteilung Mikrobiologie, Technische Universität München, Germany
| | - Konrad Trülzsch
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie, Ludwig-Maximilians-Universität, München, Germany
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50
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Pratt JT, Ismail AM, Camilli A. PhoB regulates both environmental and virulence gene expression in Vibrio cholerae. Mol Microbiol 2010; 77:1595-605. [PMID: 20659293 DOI: 10.1111/j.1365-2958.2010.07310.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Vibrio cholerae is a facultative pathogen that thrives in two nutritionally disparate environments, aquatic and human small intestine. Phosphate (P(i) ) is an essential nutrient that is limited in aquatic ecosystems and of unknown availability in the small intestine. Here, we show that the P(i) (Pho) regulon, which is controlled by the P(i)-specific transporter (Pst) and two-component system PhoBR, is required for V. cholerae survival in both environments, though for differing reasons. While induction of P(i) acquisition systems including Pst is critical for survival in the aquatic environment, regulation of virulence genes by PhoB and not P(i) transport per se is required for colonization of the small intestine. We show that PhoB regulates virulence genes by directly controlling expression of a key upstream transcriptional regulator, tcpPH. Thus, the Pho regulon includes virulence genes and represents a diverse gene set essential to pathogenic V. cholerae throughout its life cycle.
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Affiliation(s)
- Jason T Pratt
- Howard Hughes Medical Institute and Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
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