1
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Chen T, Pu M, Subramanian S, Kearns D, Rowe-Magnus D. PlzD modifies Vibrio vulnificus foraging behavior and virulence in response to elevated c-di-GMP. mBio 2023; 14:e0153623. [PMID: 37800901 PMCID: PMC10653909 DOI: 10.1128/mbio.01536-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 08/21/2023] [Indexed: 10/07/2023] Open
Abstract
IMPORTANCE Many free-swimming bacteria propel themselves through liquid using rotary flagella, and mounting evidence suggests that the inhibition of flagellar rotation initiates biofilm formation, a sessile lifestyle that is a nearly universal surface colonization paradigm in bacteria. In general, motility and biofilm formation are inversely regulated by the intracellular second messenger bis-(3´-5´)-cyclic dimeric guanosine monophosphate (c-di-GMP). Here, we identify a protein, PlzD, bearing a conserved c-di-GMP binding PilZ domain that localizes to the flagellar pole in a c-di-GMP-dependent manner and alters the foraging behavior, biofilm, and virulence characteristics of the opportunistic human pathogen, Vibrio vulnificus. Our data suggest that PlzD interacts with components of the flagellar stator to decrease bacterial swimming speed and changes in swimming direction, and these activities are enhanced when cellular c-di-GMP levels are elevated. These results reveal a physical link between a second messenger (c-di-GMP) and an effector (PlzD) that promotes transition from a motile to a sessile state in V. vulnificus.
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Affiliation(s)
- Tianyi Chen
- Department of Biology, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Meng Pu
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
| | - Sundharraman Subramanian
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - Dan Kearns
- Department of Biology, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Dean Rowe-Magnus
- Department of Biology, Indiana University Bloomington, Bloomington, Indiana, USA
- Department of Molecular and Cellular Biochemistry, Indiana University Bloomington, Bloomington, Indiana, USA
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2
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López-Pérez M, Jayakumar JM, Grant TA, Zaragoza-Solas A, Cabello-Yeves PJ, Almagro-Moreno S. Ecological diversification reveals routes of pathogen emergence in endemic Vibrio vulnificus populations. Proc Natl Acad Sci U S A 2021; 118:e2103470118. [PMID: 34593634 PMCID: PMC8501797 DOI: 10.1073/pnas.2103470118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2021] [Indexed: 12/17/2022] Open
Abstract
Pathogen emergence is a complex phenomenon that, despite its public health relevance, remains poorly understood. Vibrio vulnificus, an emergent human pathogen, can cause a deadly septicaemia with over 50% mortality rate. To date, the ecological drivers that lead to the emergence of clinical strains and the unique genetic traits that allow these clones to colonize the human host remain mostly unknown. We recently surveyed a large estuary in eastern Florida, where outbreaks of the disease frequently occur, and found endemic populations of the bacterium. We established two sampling sites and observed strong correlations between location and pathogenic potential. One site is significantly enriched with strains that belong to one phylogenomic cluster (C1) in which the majority of clinical strains belong. Interestingly, strains isolated from this site exhibit phenotypic traits associated with clinical outcomes, whereas strains from the second site belong to a cluster that rarely causes disease in humans (C2). Analyses of C1 genomes indicate unique genetic markers in the form of clinical-associated alleles with a potential role in virulence. Finally, metagenomic and physicochemical analyses of the sampling sites indicate that this marked cluster distribution and genetic traits are strongly associated with distinct biotic and abiotic factors (e.g., salinity, nutrients, or biodiversity), revealing how ecosystems generate selective pressures that facilitate the emergence of specific strains with pathogenic potential in a population. This knowledge can be applied to assess the risk of pathogen emergence from environmental sources and integrated toward the development of novel strategies for the prevention of future outbreaks.
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Affiliation(s)
- Mario López-Pérez
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816
- National Center for Integrated Coastal Research, University of Central Florida, Orlando, FL 32816
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, 03550 Alicante, Spain
| | - Jane M Jayakumar
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816
- National Center for Integrated Coastal Research, University of Central Florida, Orlando, FL 32816
| | - Trudy-Ann Grant
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816
- National Center for Integrated Coastal Research, University of Central Florida, Orlando, FL 32816
| | - Asier Zaragoza-Solas
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, 03550 Alicante, Spain
| | - Pedro J Cabello-Yeves
- Evolutionary Genomics Group, División de Microbiología, Universidad Miguel Hernández, 03550 Alicante, Spain
| | - Salvador Almagro-Moreno
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816;
- National Center for Integrated Coastal Research, University of Central Florida, Orlando, FL 32816
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3
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Vibrio cholerae Type VI Activity Alters Motility Behavior in Mucin. J Bacteriol 2020; 202:JB.00261-20. [PMID: 32868403 DOI: 10.1128/jb.00261-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/11/2020] [Indexed: 01/16/2023] Open
Abstract
Motility is required for many bacterial pathogens to reach and colonize target sites. Vibrio cholerae traverses a thick mucus barrier coating the small intestine to reach the underlying epithelium. We screened a transposon library in motility medium containing mucin to identify factors that influence mucus transit. Lesions in structural genes of the type VI secretion system (T6SS) were among those recovered. Two-dimensional (2D) and 3D single-cell tracking was used to compare the motility behaviors of wild-type cells and a mutant that collectively lacked three essential T6SS structural genes (T6SS-). In the absence of mucin, wild-type and T6SS- cells exhibited similar speeds and run-reverse-flick (RRF) swimming patterns, in which forward-moving cells briefly backtrack before stochastically reorienting (flicking) in a new direction upon resuming forward movement. We show that mucin induced T6SS expression and activity in wild-type bacteria but significantly decreased their swimming speed and flicking, yielding curvilinear or near-surface circular traces for many cells. Conversely, mucin slowed T6SS- cells to a lesser extent, and many continued to flick and produce RRF-like traces. ΔcheY3 cells, which exclusively swim in the forward direction and thus cannot flick, also produced curvilinear traces with or without mucin present and, on occasion, near-surface circular traces in the presence of mucin. The dependence of flicking on swimming speed suggested that mucin-induced T6SS activity further decreased V. cholerae motility and thereby reduced flicking probability during reverse-to-forward transitions. We propose that this encourages cells to continue on their current trajectory rather than reorienting, which may benefit those tracking toward the epithelial surface.IMPORTANCE V. cholerae deploys an arsenal of virulence factors as it attempts to traverse a protective mucus layer and reach the epithelial surface of the distal small intestine. The T6SS used to cull bacterial competition during infection is induced by mucus. We show that this activity may serve an additional purpose by further decreasing motility in the presence of mucin, thereby reducing the probability of speed-dependent, near-perpendicular directional changes. We posit that this encourages cells to maintain course rather than change direction, which may aid those attempting to reach and colonize the epithelial surface.
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4
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To H, Teshima K, Kon M, Yasuda S, Akaike Y, Shibuya K, Nagai S, Sasakawa C. Characterization of nontypeable Actinobacillus pleuropneumoniae isolates. J Vet Diagn Invest 2020; 32:581-584. [PMID: 32517629 DOI: 10.1177/1040638720931469] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Two Actinobacillus pleuropneumoniae isolates from clinical cases of porcine pleuropneumonia in Japan were positive in the capsular serovar 15-specific PCR assay, but nontypeable (NT) in the agar gel precipitation (AGP) test. Nucleotide sequence analysis of gene clusters involved in the biosynthesis of capsular polysaccharide (CPS) and lipopolysaccharide O-polysaccharide (O-PS) revealed that both clusters contained transposable element ISApl1 of A. pleuropneumoniae belonging to the IS30 family. Immunoblot analysis revealed that these 2 isolates could not produce O-PS. We conclude that the ISApl1 of A. pleuropneumoniae can interfere in the biosynthesis of both CPS and O-PS.
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Affiliation(s)
- Ho To
- Nippon Institute for Biological Science, Ome, Tokyo, Japan (To, Teshima, Kon, Yasuda, Akaike, Shibuya, Nagai, Sasakawa).,Medical Mycology Research Center, Chiba University, Chiba, Japan (Sasakawa)
| | - Kaho Teshima
- Nippon Institute for Biological Science, Ome, Tokyo, Japan (To, Teshima, Kon, Yasuda, Akaike, Shibuya, Nagai, Sasakawa).,Medical Mycology Research Center, Chiba University, Chiba, Japan (Sasakawa)
| | - Michiha Kon
- Nippon Institute for Biological Science, Ome, Tokyo, Japan (To, Teshima, Kon, Yasuda, Akaike, Shibuya, Nagai, Sasakawa).,Medical Mycology Research Center, Chiba University, Chiba, Japan (Sasakawa)
| | - Saori Yasuda
- Nippon Institute for Biological Science, Ome, Tokyo, Japan (To, Teshima, Kon, Yasuda, Akaike, Shibuya, Nagai, Sasakawa).,Medical Mycology Research Center, Chiba University, Chiba, Japan (Sasakawa)
| | - Yuta Akaike
- Nippon Institute for Biological Science, Ome, Tokyo, Japan (To, Teshima, Kon, Yasuda, Akaike, Shibuya, Nagai, Sasakawa).,Medical Mycology Research Center, Chiba University, Chiba, Japan (Sasakawa)
| | - Kazumoto Shibuya
- Nippon Institute for Biological Science, Ome, Tokyo, Japan (To, Teshima, Kon, Yasuda, Akaike, Shibuya, Nagai, Sasakawa).,Medical Mycology Research Center, Chiba University, Chiba, Japan (Sasakawa)
| | - Shinya Nagai
- Nippon Institute for Biological Science, Ome, Tokyo, Japan (To, Teshima, Kon, Yasuda, Akaike, Shibuya, Nagai, Sasakawa).,Medical Mycology Research Center, Chiba University, Chiba, Japan (Sasakawa)
| | - Chihiro Sasakawa
- Nippon Institute for Biological Science, Ome, Tokyo, Japan (To, Teshima, Kon, Yasuda, Akaike, Shibuya, Nagai, Sasakawa).,Medical Mycology Research Center, Chiba University, Chiba, Japan (Sasakawa)
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5
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Pettis GS, Mukerji AS. Structure, Function, and Regulation of the Essential Virulence Factor Capsular Polysaccharide of Vibrio vulnificus. Int J Mol Sci 2020; 21:ijms21093259. [PMID: 32380667 PMCID: PMC7247339 DOI: 10.3390/ijms21093259] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 05/01/2020] [Accepted: 05/03/2020] [Indexed: 12/23/2022] Open
Abstract
Vibrio vulnificus populates coastal waters around the world, where it exists freely or becomes concentrated in filter feeding mollusks. It also causes rapid and life-threatening sepsis and wound infections in humans. Of its many virulence factors, it is the V. vulnificus capsule, composed of capsular polysaccharide (CPS), that plays a critical role in evasion of the host innate immune system by conferring antiphagocytic ability and resistance to complement-mediated killing. CPS may also provoke a portion of the host inflammatory cytokine response to this bacterium. CPS production is biochemically and genetically diverse among strains of V. vulnificus, and the carbohydrate diversity of CPS is likely affected by horizontal gene transfer events that result in new combinations of biosynthetic genes. Phase variation between virulent encapsulated opaque colonial variants and attenuated translucent colonial variants, which have little or no CPS, is a common phenotype among strains of this species. One mechanism for generating acapsular variants likely involves homologous recombination between repeat sequences flanking the wzb phosphatase gene within the Group 1 CPS biosynthetic and transport operon. A considerable number of environmental, genetic, and regulatory factors have now been identified that affect CPS gene expression and CPS production in this pathogen.
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6
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Pu M, Storms E, Chodur DM, Rowe-Magnus DA. Calcium-dependent site-switching regulates expression of the atypical iam pilus locus in Vibrio vulnificus. Environ Microbiol 2019; 22:4167-4182. [PMID: 31355512 DOI: 10.1111/1462-2920.14763] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Accepted: 07/25/2019] [Indexed: 12/21/2022]
Abstract
The opportunistic human pathogen Vibrio vulnificus inhabits warm coastal waters and asymptomatically colonizes seafood, most commonly oysters. We previously characterized an isolate that exhibited greater biofilm formation, aggregation and oyster colonization than its parent. This was due, in part, to the production of a Type IV Tad pilus (Iam). However, the locus lacked key processing and regulatory genes required for pilus production. Here, we identify a pilin peptidase iamP, and LysR-type regulator (LRTR) iamR, that fulfil these roles and show that environmental calcium, which oysters enrich for shell repair and growth, regulates iam expression. The architecture of the iam locus differs from the classical LRTR paradigm and requires an additional promoter to be integrated into the regulatory network. IamR specifically recognized the iamR promoter (PiamR ) and the intergenic iamP-iamA region (PiamP-A ). PiamR exhibited classical negative auto-regulation but, strikingly, IamR inversely regulated the divergent iamP and iamA promoters in a calcium-dependent manner. Moreover, expression of the c-di-GMP and calcium-regulated, biofilm-promoting brp exopolysaccharide was IamA-dependent. These results support a scenario in which the calcium-enriched oyster environment triggers IamP-mediated processing of prepilin amassed in the periplasm for rapid pilin elaboration and subsequent BRP production to promote colonization.
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Affiliation(s)
- Meng Pu
- Department of Biology, Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Emily Storms
- Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Dan M Chodur
- Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Dean A Rowe-Magnus
- Department of Biology, Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA.,Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
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7
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Li Y, Tang M, Wang G, Li C, Chen W, Luo Y, Zeng J, Hu X, Zhou Y, Gao Y, Zhang L. Genomic characterization of Kerstersia gyiorum SWMUKG01, an isolate from a patient with respiratory infection in China. PLoS One 2019; 14:e0214686. [PMID: 30978196 PMCID: PMC6461280 DOI: 10.1371/journal.pone.0214686] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 03/18/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The Gram-negative bacterium Kerstersia gyiorum, a potential etiological agent of clinical infections, was isolated from several human patients presenting clinical symptoms. Its significance as a possible pathogen has been previously overlooked as no disease has thus far been definitively associated with this bacterium. To better understand how the organism contributes to the infectious disease, we determined the complete genomic sequence of K. gyiorum SWMUKG01, the first clinical isolate from southwest China. RESULTS The genomic data obtained displayed a single circular chromosome of 3, 945, 801 base pairs in length, which contains 3, 441 protein-coding genes, 55 tRNA genes and 9 rRNA genes. Analysis on the full spectrum of protein coding genes for cellular structures, two-component regulatory systems and iron uptake pathways that may be important for the success of the bacterial survival, colonization and establishment in the host conferred new insights into the virulence characteristics of K. gyiorum. Phylogenomic comparisons with Alcaligenaceae species indicated that K. gyiorum SWMUKG01 had a close evolutionary relationships with Alcaligenes aquatilis and Alcaligenes faecalis. CONCLUSIONS The comprehensive analysis presented in this work determinates for the first time a complete genome sequence of K. gyiorum, which is expected to provide useful information for subsequent studies on pathogenesis of this species.
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Affiliation(s)
- Ying Li
- Department of Immunology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
| | - Min Tang
- Department of Pathogenic Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
| | - Guangxi Wang
- Department of Pathogenic Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
| | - Chengwen Li
- Department of Immunology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
| | - Wenbi Chen
- Department of Pathogenic Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
| | - Yonghong Luo
- Department of Physiology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
| | - Jing Zeng
- Department of Pathogenic Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
| | - Xiaoyan Hu
- Department of Pathogenic Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
| | - Yungang Zhou
- Department of Immunology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
| | - Yan Gao
- Department of Immunology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
| | - Luhua Zhang
- Department of Pathogenic Biology, School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, China
- * E-mail:
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8
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Environmental Calcium Initiates a Feed-Forward Signaling Circuit That Regulates Biofilm Formation and Rugosity in Vibrio vulnificus. mBio 2018; 9:mBio.01377-18. [PMID: 30154262 PMCID: PMC6113621 DOI: 10.1128/mbio.01377-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The second messenger c-di-GMP is a key regulator of bacterial physiology. The V. vulnificus genome encodes nearly 100 proteins predicted to make, break, and bind c-di-GMP. However, relatively little is known regarding the environmental signals that regulate c-di-GMP levels and biofilm formation in V. vulnificus. Here, we identify calcium as a primary environmental signal that specifically increases intracellular c-di-GMP concentrations, which in turn triggers brp-mediated biofilm formation. We show that PAPS, a metabolic intermediate of the sulfate assimilation pathway, acts as a second messenger linking environmental calcium and sulfur source availability to the production of another intracellular second messenger (c-di-GMP) to regulate biofilm and rugose colony formation, developmental pathways that are associated with environmental persistence and efficient bivalve colonization by this potent human pathogen. Poor clinical outcomes (disfigurement, amputation, and death) and significant economic losses in the aquaculture industry can be attributed to the potent opportunistic human pathogen Vibrio vulnificus. V. vulnificus, as well as the bivalves (oysters) it naturally colonizes, is indigenous to estuaries and human-inhabited coastal regions and must endure constantly changing environmental conditions as freshwater and seawater enter, mix, and exit the water column. Elevated cellular c-di-GMP levels trigger biofilm formation, but relatively little is known regarding the environmental signals that initiate this response. Here, we show that calcium is a primary environmental signal that specifically increases intracellular c-di-GMP concentrations, which in turn triggers expression of the brp extracellular polysaccharide that enhances biofilm formation. A transposon screen for the loss of calcium-induced PbrpA expression revealed CysD, an enzyme in the sulfate assimilation pathway. Targeted disruption of the pathway indicated that the production of a specific metabolic intermediate, 3′-phosphoadenosine 5′-phosphosulfate (PAPS), was required for calcium-induced PbrpA expression and that PAPS was separately required for development of the physiologically distinct rugose phenotype. Thus, PAPS behaves as a second messenger in V. vulnificus. Moreover, c-di-GMP and BrpT (the activator of brp expression) acted in concert to bias expression of the sulfate assimilation pathway toward PAPS and c-di-GMP accumulation, establishing a feed-forward regulatory loop to boost brp expression. Thus, this signaling network links extracellular calcium and sulfur availability to the intracellular second messengers PAPS and c-di-GMP in the regulation of V. vulnificus biofilm formation and rugosity, survival phenotypes underpinning its evolution as a resilient environmental organism.
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9
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Huang X, Chen C, Ren C, Li Y, Deng Y, Yang Y, Ding X. Identification and characterization of a locus putatively involved in colanic acid biosynthesis in Vibrio alginolyticus ZJ-51. BIOFOULING 2018; 34:1-14. [PMID: 29210309 DOI: 10.1080/08927014.2017.1400020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
Colanic acid (CA) is a group I extracellular polysaccharide (EPS) that contributes to resistance against adverse environments in many members of the Enterobacteriaceae. In the present study, a genetic locus EPSC putatively involved in CA biosynthesis was identified in Vibrio alginolyticus ZJ-51, which undergoes colony morphology variation between translucent/smooth (ZJ-T) and opaque/rugose (ZJ-O). EPSC in ZJ-T carries 21 ORFs and resembles the CA cluster of Escherichia coli K-12. The deletion of EPSC led to decreased EPS and biofilm formation in both genetic backgrounds but no alternation of lipopolysaccharide. The loss of this locus also changed the colony morphology of ZJ-O on the 2216E plate and reduced the motility of ZJ-T. Compared with ZJ-T, ZJ-O lacks a 10-kb fragment (epsT) in EPSC containing homologs of wecA, wzx and wzy that are essential for O-antigen synthesis. However, the deletion or overexpression of epsT resulted in no change of colony morphology, biofilm formation or EPS production. This study reported at the first time a genetic locus EPSC that may be involved in colanic acid synthesis in V. alginolyticus ZJ-51, and found that it was related to EPS biosynthesis, biofilm formation, colony morphology and motility, which may shed light on the environmental adaptation of the vibrios.
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Affiliation(s)
- Xiaochun Huang
- a Key Laboratory of Tropical Marine Bio-resources and Ecology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , PR China
- b Guangdong Provincial Key Laboratory of Applied Marine Biology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , China
- d University of Chinese Academy of Sciences , Beijing , PR China
| | - Chang Chen
- a Key Laboratory of Tropical Marine Bio-resources and Ecology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , PR China
- b Guangdong Provincial Key Laboratory of Applied Marine Biology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , China
- c Xisha Deep Sea Marine Environment Observation and Research Station , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , PR China
| | - Chunhua Ren
- a Key Laboratory of Tropical Marine Bio-resources and Ecology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , PR China
| | - Yingying Li
- e College of Life Science and Technology , Jinan University , Guangzhou , PR China
| | - Yiqin Deng
- a Key Laboratory of Tropical Marine Bio-resources and Ecology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , PR China
- b Guangdong Provincial Key Laboratory of Applied Marine Biology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , China
- d University of Chinese Academy of Sciences , Beijing , PR China
| | - Yiying Yang
- a Key Laboratory of Tropical Marine Bio-resources and Ecology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , PR China
- b Guangdong Provincial Key Laboratory of Applied Marine Biology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , China
- d University of Chinese Academy of Sciences , Beijing , PR China
| | - Xiongqi Ding
- a Key Laboratory of Tropical Marine Bio-resources and Ecology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , PR China
- b Guangdong Provincial Key Laboratory of Applied Marine Biology , South China Sea Institution of Oceanology, University of Chinese Academy of Sciences , Guangzhou , China
- d University of Chinese Academy of Sciences , Beijing , PR China
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10
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Pu M, Duriez P, Arazi M, Rowe-Magnus DA. A conserved tad pilus promotesVibrio vulnificusoyster colonization. Environ Microbiol 2017; 20:828-841. [DOI: 10.1111/1462-2920.14025] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 10/17/2017] [Accepted: 12/07/2017] [Indexed: 12/23/2022]
Affiliation(s)
- Meng Pu
- Molecular and Cellular Biochemistry; Indiana University Bloomington; IN USA
| | - Patrick Duriez
- Department of Biology and Indiana University Bloomington; IN USA
| | - Mattan Arazi
- Department of Biology and Indiana University Bloomington; IN USA
| | - Dean A. Rowe-Magnus
- Molecular and Cellular Biochemistry; Indiana University Bloomington; IN USA
- Department of Biology and Indiana University Bloomington; IN USA
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11
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Hampton CM, Guerrero-Ferreira RC, Storms RE, Taylor JV, Yi H, Gulig PA, Wright ER. The Opportunistic Pathogen Vibrio vulnificus Produces Outer Membrane Vesicles in a Spatially Distinct Manner Related to Capsular Polysaccharide. Front Microbiol 2017; 8:2177. [PMID: 29163452 PMCID: PMC5681939 DOI: 10.3389/fmicb.2017.02177] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 10/23/2017] [Indexed: 12/11/2022] Open
Abstract
Vibrio vulnificus, a bacterial species that inhabits brackish waters, is an opportunistic pathogen of humans. V. vulnificus infections can cause acute gastroenteritis, invasive septicemia, tissue necrosis, and potentially death. Virulence factors associated with V. vulnificus include the capsular polysaccharide (CPS), lipopolysaccharide, flagellum, pili, and outer membrane vesicles (OMVs). The aims of this study were to characterize the morphology of V. vulnificus cells and the formation and arrangement of OMVs using cryo-electron microscopy (cryo-EM). cryo-EM and cryo-electron tomography imaging of V. vulnificus strains grown in liquid cultures revealed the presence of OMVs (diameters of ∼45 nm for wild-type, ∼30 nm for the unencapsulated mutant, and ∼50 nm for the non-motile mutant) in log-phase growth. Production of OMVs in the stationary growth phase was limited and irregular. The spacing of the OMVs around the wild-type cells was in regular, concentric rings. In wild-type cells and a non-motile mutant, the spacing between the cell envelope and the first ring of OMVs was ∼200 nm; this spacing was maintained between subsequent OMV layers. The size, arrangement, and spacing of OMVs in an unencapsulated mutant was irregular and indicated that the polysaccharide chains of the capsule regulate aspects of OMV production and order. Together, our results revealed the distinctive organization of V. vulnificus OMVs that is affected by expression of the CPS.
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Affiliation(s)
- Cheri M Hampton
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, United States
| | - Ricardo C Guerrero-Ferreira
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, United States
| | - Rachel E Storms
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, United States
| | - Jeannette V Taylor
- Robert P. Apkarian Integrated Electron Microscopy Core, Emory University, Atlanta, GA, United States
| | - Hong Yi
- Robert P. Apkarian Integrated Electron Microscopy Core, Emory University, Atlanta, GA, United States
| | - Paul A Gulig
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL, United States
| | - Elizabeth R Wright
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Children's Healthcare of Atlanta, Atlanta, GA, United States.,Robert P. Apkarian Integrated Electron Microscopy Core, Emory University, Atlanta, GA, United States
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12
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The Proline Variant of the W[F/L/M][T/S]R Cyclic Di-GMP Binding Motif Suppresses Dependence on Signal Association for Regulator Function. J Bacteriol 2017; 199:JB.00344-17. [PMID: 28652300 DOI: 10.1128/jb.00344-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 06/19/2017] [Indexed: 12/21/2022] Open
Abstract
Vibrio vulnificus is an estuarine bacterium and potent opportunistic human pathogen. It enters the food chain by asymptomatically colonizing a variety of marine organisms, most notably oysters. Expression of the brp-encoded extracellular polysaccharide, which enhances cell-surface adherence, is regulated by cyclic di-GMP (c-di-GMP) and the activator BrpT. The Vibrio cholerae and Vibrio parahaemolyticus homologs VpsT and CpsQ, directly bind c-di-GMP via a novel W[F/L/M][T/S]R motif, and c-di-GMP binding is absolutely required for activity. Notably, BrpT belongs to a distinct subclass of VpsT-like regulators that harbor a proline in the third position of the c-di-GMP binding motif (WLPR), and the impact of this change on activity is unknown. We show that the brp locus is organized as two linked operons with BrpT specifically binding to promoters upstream of brpA and brpH Expression data and structural modeling suggested that BrpT might be less dependent on c-di-GMP binding for activity than VpsT or CpsQ. We show that the affinity of BrpT for c-di-GMP is low and that signal binding is not a requisite for BrpT function. Furthermore, a BrpT mutant engineered to carry a canonical WLTR motif (BrpTP124T) bound c-di-GMP with high affinity and its activity was now c-di-GMP dependent. Conversely, introduction of the WLPR motif into VpsT suppressed its dependence on c-di-GMP for activity. This is the first demonstration of reduced dependence on signal association for regulator function within this motif family. Thus, BrpT defines a new class of VpsT-like transcriptional regulators, and the WLPR motif variant may similarly liberate the activity of other subclass members.IMPORTANCE A Vibrio genome may encode nearly 100 proteins that make, break, and bind c-di-GMP, underscoring its central role in the physiology of these bacteria. The activity of the biofilm regulators VpsT of V. cholerae and CpsQ of V. parahaemolyticus is regulated by the direct binding of c-di-GMP via a novel W[F/L/M][T/S]R motif. The V. vulnificus homolog, BrpT, bears an unusual WLPR variant and remains active at low intracellular c-di-GMP levels. This suggests that the WLPR motif may also liberate the activity of other members of this subclass. A single point mutation at the 3rd position of the motif was sufficient to moderate dependence on c-di-GMP binding for activator function, highlighting the simplicity with which complex bacterial signaling networks can be rewired.
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Garrett SB, Garrison-Schilling KL, Cooke JT, Pettis GS. Capsular polysaccharide production and serum survival of Vibrio vulnificus are dependent on antitermination control by RfaH. FEBS Lett 2016; 590:4564-4572. [PMID: 27859050 DOI: 10.1002/1873-3468.12490] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/06/2016] [Accepted: 11/10/2016] [Indexed: 12/19/2022]
Abstract
The human pathogen Vibrio vulnificus undergoes phase variation among colonial morphotypes, including a virulent opaque form which produces capsular polysaccharide (CPS) and a translucent phenotype that produces little or no CPS and is attenuated. Here, we found that a V. vulnificus mutant defective for RfaH antitermination control showed a diminished capacity to undergo phase variation and displayed significantly reduced distal gene expression within the Group I CPS operon. Moreover, the rfaH mutant produced negligible CPS and was highly sensitive to killing by normal human serum, results which indicate that RfaH is likely essential for virulence in this bacterium.
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Affiliation(s)
- Shana B Garrett
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | | | - Jeffrey T Cooke
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - Gregg S Pettis
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
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14
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Ch Ho E, Buckley KM, Schrankel CS, Schuh NW, Hibino T, Solek CM, Bae K, Wang G, Rast JP. Perturbation of gut bacteria induces a coordinated cellular immune response in the purple sea urchin larva. Immunol Cell Biol 2016; 94:861-874. [PMID: 27192936 PMCID: PMC5073156 DOI: 10.1038/icb.2016.51] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 05/12/2016] [Accepted: 05/12/2016] [Indexed: 02/07/2023]
Abstract
The purple sea urchin (Strongylocentrotus purpuratus) genome sequence contains a complex repertoire of genes encoding innate immune recognition proteins and homologs of important vertebrate immune regulatory factors. To characterize how this immune system is deployed within an experimentally tractable, intact animal, we investigate the immune capability of the larval stage. Sea urchin embryos and larvae are morphologically simple and transparent, providing an organism-wide model to view immune response at cellular resolution. Here we present evidence for immune function in five mesenchymal cell types based on morphology, behavior and gene expression. Two cell types are phagocytic; the others interact at sites of microbial detection or injury. We characterize immune-associated gene markers for three cell types, including a perforin-like molecule, a scavenger receptor, a complement-like thioester-containing protein and the echinoderm-specific immune response factor 185/333. We elicit larval immune responses by (1) bacterial injection into the blastocoel and (2) seawater exposure to the marine bacterium Vibrio diazotrophicus to perturb immune state in the gut. Exposure at the epithelium induces a strong response in which pigment cells (one type of immune cell) migrate from the ectoderm to interact with the gut epithelium. Bacteria that accumulate in the gut later invade the blastocoel, where they are cleared by phagocytic and granular immune cells. The complexity of this coordinated, dynamic inflammatory program within the simple larval morphology provides a system in which to characterize processes that direct both aspects of the echinoderm-specific immune response as well as those that are shared with other deuterostomes, including vertebrates.
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Affiliation(s)
- Eric Ch Ho
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Katherine M Buckley
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Catherine S Schrankel
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Nicholas W Schuh
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Taku Hibino
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Cynthia M Solek
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Koeun Bae
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Guizhi Wang
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Jonathan P Rast
- Biological Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
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15
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Phillips NJ, John CM, Jarvis GA. Analysis of Bacterial Lipooligosaccharides by MALDI-TOF MS with Traveling Wave Ion Mobility. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1263-1276. [PMID: 27056565 DOI: 10.1007/s13361-016-1383-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/11/2016] [Accepted: 03/12/2016] [Indexed: 06/05/2023]
Abstract
Lipooligosaccharides (LOS) are major microbial virulence factors displayed on the outer membrane of rough-type Gram-negative bacteria. These amphipathic glycolipids are comprised of two domains, a core oligosaccharide linked to a lipid A moiety. Isolated LOS samples are generally heterogeneous mixtures of glycoforms, with structural variability in both domains. Traditionally, the oligosaccharide and lipid A components of LOS have been analyzed separately following mild acid hydrolysis, although important acid-labile moieties can be cleaved. Recently, an improved method was introduced for analysis of intact LOS by MALDI-TOF MS using a thin layer matrix composed of 2,4,6-trihydroxyacetophenone (THAP) and nitrocellulose. In addition to molecular ions, the spectra show in-source "prompt" fragments arising from regiospecific cleavage between the lipid A and oligosaccharide domains. Here, we demonstrate the use of traveling wave ion mobility spectrometry (TWIMS) for IMS-MS and IMS-MS/MS analyses of intact LOS from Neisseria spp. ionized by MALDI. Using IMS, the singly charged prompt fragments for the oligosaccharide and lipid A domains of LOS were readily separated into resolved ion plumes, permitting the extraction of specific subspectra, which led to increased confidence in assigning compositions and improved detection of less abundant ions. Moreover, IMS separation of precursor ions prior to collision-induced dissociation (CID) generated time-aligned, clean MS/MS spectra devoid of fragments from interfering species. Incorporating IMS into the profiling of intact LOS by MALDI-TOF MS exploits the unique domain structure of the molecule and offers a new means of extracting more detailed information from the analysis. Graphical Abstract ᅟ.
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Affiliation(s)
- Nancy J Phillips
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, 94143, USA
| | - Constance M John
- Center for Immunochemistry, Veterans Affairs Medical Center, 4150 Clement Street, San Francisco, CA, 94121, USA
- Department of Laboratory Medicine, University of California, San Francisco, CA, 94143, USA
| | - Gary A Jarvis
- Center for Immunochemistry, Veterans Affairs Medical Center, 4150 Clement Street, San Francisco, CA, 94121, USA.
- Department of Laboratory Medicine, University of California, San Francisco, CA, 94143, USA.
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Taylor VL, Hoage JFJ, Thrane SW, Huszczynski SM, Jelsbak L, Lam JS. A Bacteriophage-Acquired O-Antigen Polymerase (Wzyβ) from P. aeruginosa Serotype O16 Performs a Varied Mechanism Compared to Its Cognate Wzyα. Front Microbiol 2016; 7:393. [PMID: 27065964 PMCID: PMC4815439 DOI: 10.3389/fmicb.2016.00393] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/14/2016] [Indexed: 12/23/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative bacterium that produces highly varied lipopolysaccharide (LPS) structures. The O antigen (O-Ag) in the LPS is synthesized through the Wzx/Wzy-dependent pathway where lipid-linked O-Ag repeats are polymerized by Wzy. Horizontal-gene transfer has been associated with O-Ag diversity. The O-Ag present on the surface of serotypes O5 and O16, differ in the intra-molecular bonds, α and β, respectively; the latter arose from the action of three genes in a serotype converting unit acquired from bacteriophage D3, including a β-polymerase (Wzyβ). To further our understanding of O-polymerases, the inner membrane (IM) topology of Wzyβ was determined using a dual phoA-lacZα reporter system wherein random 3′ gene truncations were localized to specific loci with respect to the IM by normalized reporter activities as determined through the ratio of alkaline phosphatase activity to β-galactosidase activity. The topology of Wzyβ developed through this approach was shown to contain two predominant periplasmic loops, PL3 (containing an RX10G motif) and PL4 (having an O-Ag ligase superfamily motif), associated with inverting glycosyltransferase reaction. Through site-directed mutagenesis and complementation assays, residues Arg254, Arg270, Arg272, and His300 were found to be essential for Wzyβ function. Additionally, like-charge substitutions, R254K and R270K, could not complement the wzyβ knockout, highlighting the essential guanidium side group of Arg residues. The O-Ag ligase domain is conserved among heterologous Wzy proteins that produce β-linked O-Ag repeat units. Taking advantage of the recently obtained whole-genome sequence of serotype O16 a candidate promoter was identified. Wzyβ under its native promoter was integrated in the PAO1 genome, which resulted in simultaneous production of α- and β-linked O-Ag. These observations established that members of Wzy-like family consistently exhibit a dual-periplasmic loops topology, and identifies motifs that are plausible to be involved in enzymatic activities. Based on these results, the phage-derived Wzyβ utilizes a different reaction mechanism in the P. aeruginosa host to avoid self-inhibition during serotype conversion.
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Affiliation(s)
- Véronique L Taylor
- Department of Molecular and Cellular Biology, University of Guelph Guelph, ON, Canada
| | - Jesse F J Hoage
- Department of Molecular and Cellular Biology, University of Guelph Guelph, ON, Canada
| | | | - Steven M Huszczynski
- Department of Molecular and Cellular Biology, University of Guelph Guelph, ON, Canada
| | - Lars Jelsbak
- Department of Systems Biology, Technical University of Denmark Kongens Lyngby, Denmark
| | - Joseph S Lam
- Department of Molecular and Cellular Biology, University of Guelph Guelph, ON, Canada
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17
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Marshall JM, Gunn JS. The O-Antigen Capsule of Salmonella enterica Serovar Typhimurium Facilitates Serum Resistance and Surface Expression of FliC. Infect Immun 2015; 83:3946-59. [PMID: 26195553 PMCID: PMC4567616 DOI: 10.1128/iai.00634-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 07/16/2015] [Indexed: 11/20/2022] Open
Abstract
Group IV polysaccharide capsules are common in enteric bacteria and have more recently been described in nontyphoidal Salmonella species. Such capsules are known as O-antigen (O-Ag) capsules, due to their high degree of similarity to the O-Ag of the lipopolysaccharide (LPSO-Ag). Capsular polysaccharides are known virulence factors of many bacterial pathogens, facilitating evasion of immune recognition and systemic dissemination within the host. Previous studies on the O-Ag capsule of salmonellae have focused primarily on its role in bacterial surface attachment and chronic infection; however, the potential effects of the O-Ag capsule on acute pathogenesis have yet to be investigated. While much of the in vivo innate immune resistance of Salmonella enterica serovar Typhimurium is attributed to the high-molecular-weight LPS, we hypothesized that the O-Ag capsule may enhance this resistance by diminishing surface expression of pathogen-associated molecular patterns, such as flagella, and increasing resistance to host immune molecules. To test this hypothesis, O-Ag capsule-deficient mutants were constructed, and the loss of O-Ag capsular surface expression was confirmed through microscopy and immunoblotting. Loss of O-Ag capsule production did not alter bacterial growth or production of LPS. Western blot analysis and confocal microscopy revealed that O-Ag capsule-deficient mutants demonstrate reduced resistance to killing by human serum. Furthermore, O-Ag capsule-deficient mutants produced exclusively phase I flagellin (FliC). Although O-Ag capsule-deficient mutants did not exhibit reduced virulence in a murine model of acute infection, in vitro results indicate that the O-Ag capsule may function to modify the antigenic nature of the bacterial surface, warranting additional investigation of a potential role of the structure in pathogenesis.
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Affiliation(s)
- Joanna M Marshall
- Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, USA
| | - John S Gunn
- Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, USA
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18
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Role of anaerobiosis in capsule production and biofilm formation in Vibrio vulnificus. Infect Immun 2014; 83:551-9. [PMID: 25404024 DOI: 10.1128/iai.02559-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Vibrio vulnificus, a pervasive human pathogen, can cause potentially fatal septicemia after consumption of undercooked seafood. Biotype 1 strains of V. vulnificus are most commonly associated with human infection and are separated into two genotypes, clinical (C) and environmental (E), based on the virulence-correlated gene. For ingestion-based vibriosis to occur, this bacterium must be able to withstand multiple conditions as it traverses the gastrointestinal tract and ultimately gains entry into the bloodstream. One such condition, anoxia, has yet to be extensively researched in V. vulnificus. We investigated the effect of oxygen availability on capsular polysaccharide (CPS) production and biofilm formation in this bacterium, both of which are thought to be important for disease progression. We found that lack of oxygen elicits a reduction in both CPS and biofilm formation in both genotypes. This is further supported by the finding that pilA, pilD, and mshA genes, all of which encode type IV pilin proteins that aid in attachment to surfaces, were downregulated during anaerobiosis. Surprisingly, E-genotypes exhibited distinct differences in gene expression levels of capsule and attachment genes compared to C-genotypes, both aerobically and anaerobically. The importance of understanding these disparities may give insight into the observed differences in environmental occurrence and virulence potential between these two genotypes of V. vulnificus.
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19
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Genome sequence of Vibrio diabolicus and identification of the exopolysaccharide HE800 biosynthesis locus. Appl Microbiol Biotechnol 2014; 98:10165-76. [PMID: 25273176 DOI: 10.1007/s00253-014-6086-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 09/01/2014] [Accepted: 09/03/2014] [Indexed: 01/08/2023]
Abstract
Vibrio diabolicus, a marine bacterium originating from deep-sea hydrothermal vents, produces the HE800 exopolysaccharide with high value for biotechnological purposes, especially for human health. Its genome was sequenced and analyzed; phylogenetic analysis using the core genome revealed V. diabolicus is close to another deep-sea Vibrio sp. (Ex25) within the Harveyi clade and Alginolyticus group. A genetic locus homologous to the syp cluster from Vibrio fischeri was demonstrated to be involved in the HE800 production. However, few genetic particularities suggest that the regulation of syp expression may be different in V. diabolicus. The presence of several types of glycosyltransferases within the locus indicates a capacity to generate diversity in the glycosidic structure, which may confer an adaptability to environmental conditions. These results contribute to better understanding exopolysaccharide biosynthesis and for developing new efficient processes to produce this molecule for biotechnological applications.
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20
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Clifford JC, Rapicavoli JN, Roper MC. A rhamnose-rich O-antigen mediates adhesion, virulence, and host colonization for the xylem-limited phytopathogen Xylella fastidiosa. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:676-85. [PMID: 23441576 DOI: 10.1094/mpmi-12-12-0283-r] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Xylella fastidiosa is a gram-negative, xylem-limited bacterium that causes a lethal disease of grapevine called Pierce's disease. Lipopolysaccharide (LPS) composes approximately 75% of the outer membrane of gram-negative bacteria and, because it is largely displayed on the cell surface, it mediates interactions between the bacterial cell and its surrounding environment. LPS is composed of a conserved lipid A-core oligosaccharide component and a variable O-antigen portion. By targeting a key O-antigen biosynthetic gene, we demonstrate the contribution of the rhamnose-rich O-antigen to surface attachment, cell-cell aggregation, and biofilm maturation: critical steps for successful infection of the host xylem tissue. Moreover, we have demonstrated that a fully formed O-antigen moiety is an important virulence factor for Pierce's disease development in grape and that depletion of the O-antigen compromises its ability to colonize the host. It has long been speculated that cell-surface polysaccharides play a role in X. fastidiosa virulence and this study confirms that LPS is a major virulence factor for this important agricultural pathogen.
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Affiliation(s)
- Jennifer C Clifford
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA, USA
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21
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Ramos PIP, Picão RC, Vespero EC, Pelisson M, Zuleta LFG, Almeida LGP, Gerber AL, Vasconcelos ATR, Gales AC, Nicolás MF. Pyrosequencing-based analysis reveals a novel capsular gene cluster in a KPC-producing Klebsiella pneumoniae clinical isolate identified in Brazil. BMC Microbiol 2012; 12:173. [PMID: 22882772 PMCID: PMC3438125 DOI: 10.1186/1471-2180-12-173] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 05/23/2012] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND An important virulence factor of Klebsiella pneumoniae is the production of capsular polysaccharide (CPS), a thick mucus layer that allows for evasion of the host's defense and creates a barrier against antibacterial peptides. CPS production is driven mostly by the expression of genes located in a locus called cps, and the resulting structure is used to distinguish between different serotypes (K types). In this study, we report the unique genetic organization of the cps cluster from K. pneumoniae Kp13, a clinical isolate recovered during a large outbreak of nosocomial infections that occurred in a Brazilian teaching hospital. RESULTS A pyrosequencing-based approach showed that the cps region of Kp13 (cpsKp13) is 26.4 kbp in length and contains genes common, although not universal, to other strains, such as the rmlBADC operon that codes for L-rhamnose synthesis. cpsKp13 also presents some unique features, like the inversion of the wzy gene and a unique repertoire of glycosyltransferases. In silico comparison of cpsKp13 RFLP pattern with 102 previously published cps PCR-RFLP patterns showed that cpsKp13 is distinct from the C patterns of all other K serotypes. Furthermore, in vitro serotyping showed only a weak reaction with capsular types K9 and K34. We confirm that K9 cps shares common genes with cpsKp13 such as the rmlBADC operon, but lacks features like uge and Kp13-specific glycosyltransferases, while K34 capsules contain three of the five sugars that potentially form the Kp13 CPS. CONCLUSIONS We report the first description of a cps cluster from a Brazilian clinical isolate of a KPC-producing K. pneumoniae. The gathered data including K-serotyping support that Kp13's K-antigen belongs to a novel capsular serotype. The CPS of Kp13 probably includes L-rhamnose and D-galacturonate in its structure, among other residues. Because genes involved in L-rhamnose biosynthesis are absent in humans, this pathway may represent potential targets for the development of antimicrobial agents. Studying the capsular serotypes of clinical isolates is of great importance for further development of vaccines and/or novel therapeutic agents. The distribution of K-types among multidrug-resistant isolates is unknown, but our findings may encourage scientists to perform K-antigen typing of KPC-producing strains worldwide.
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22
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Lujan DK, Stanziale JA, Mostafavi AZ, Sharma S, Troutman JM. Chemoenzymatic synthesis of an isoprenoid phosphate tool for the analysis of complex bacterial oligosaccharide biosynthesis. Carbohydr Res 2012; 359:44-53. [PMID: 22925763 DOI: 10.1016/j.carres.2012.06.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 06/22/2012] [Accepted: 06/23/2012] [Indexed: 10/28/2022]
Abstract
Undecaprenyl Pyrophosphate Synthase (UPPS) is a key enzyme that catalyzes the production of bactoprenols, which act as membrane anchors for the assembly of complex bacterial oligosaccharides. One of the major hurdles in understanding the assembly of oligosaccharide assembly is a lack of chemical tools to study this process, since bactoprenols and the resulting isoprenoid-linked oligosaccharides lack handles or chromophores for use in pathway analysis. Here we describe the isolation of a new UPPS from the symbiotic microorganism Bacteroides fragilis, a key species in the human microbiome. The protein was purified to homogeneity and utilized to accept a chromophore containing farnesyl diphosphate analogue as a substrate. The analogue was utilized by the enzyme and resulted in a bactoprenyl diphosphate product with an easy to monitor tag associated with it. Furthermore, the diphosphate is shown to be readily converted to monophosphate using a common molecular biology reagent. This monophosphate product allowed for the investigation of complex oligosaccharide biosynthesis, and was used to probe the activity of glycosyltransferases involved in the well characterized Campylobacter jejuni N-linked protein glycosylation. Novel reagents similar to this will provide key tools for the study of uncharacterized oligosaccharide assemblies, and open the possibility for the development of rapid screening methodology for these biosynthetic systems.
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Affiliation(s)
- Donovan K Lujan
- Department of Chemistry, University of North Carolina at Charlotte, Charlotte, NC 28223, United States
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23
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Genetic analysis of the Cronobacter sakazakii O4 to O7 O-antigen gene clusters and development of a PCR assay for identification of all C. sakazakii O serotypes. Appl Environ Microbiol 2012; 78:3966-74. [PMID: 22447597 DOI: 10.1128/aem.07825-11] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Gram-negative bacterium Cronobacter sakazakii is an emerging food-borne pathogen that causes severe invasive infections in neonates. Variation in the O-antigen lipopolysaccharide in the outer membrane provides the basis for Gram-negative bacteria serotyping. The O-antigen serotyping scheme for C. sakazakii, which includes seven serotypes (O1 to O7), has been recently established, and the O-antigen gene clusters and specific primers for three C. sakazakii serotypes (O1, O2, and O3) have been characterized. In this study, the C. sakazakii O4, O5, O6, and O7 O-antigen gene clusters were sequenced, and gene functions were predicted on the basis of homology. C. sakazakii O4 shared a similar O-antigen gene cluster with Escherichia coli O103. The general features and anomalies of all seven C. sakazakii O-antigen gene clusters were evaluated and the relationship between O-antigen structures and their gene clusters were investigated. Serotype-specific genes for O4 to O7 were identified, and a molecular serotyping method for all C. sakazakii O serotypes, a multiplex PCR assay, was developed by screening against 136 strains of C. sakazakii and closely related species. The sensitivity of PCR-based serotyping method was determined to be 0.01 ng of genomic DNA and 10(3) CFU of each strain/ml. This study completes the elucidation of C. sakazakii O-antigen genetics and provides a molecular method suitable for the identification of C. sakazakii O1 to O7 strains.
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24
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Guo Y, Rowe-Magnus DA. Overlapping and unique contributions of two conserved polysaccharide loci in governing distinct survival phenotypes in Vibrio vulnificus. Environ Microbiol 2011; 13:2888-990. [PMID: 21895917 DOI: 10.1111/j.1462-2920.2011.02564.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
As an aetiological agent of bacterial sepsis and wound infections, Vibrio vulnificus is unique among the Vibrionacea. Its continued environmental persistence and transmission are bolstered by its ability to colonize shellfish and form biofilms on various marine biotic surfaces. We previously identified a polysaccharide locus, brp, which contributes to the survival phenotypes of biofilm formation, rugose colony formation and stress resistance. Here, we describe a second polysaccharide locus, rbd (regulation of biofilm development), which also enhanced biofilm formation when expressed. Despite this functional overlap, the development of stress resistance and rugosity could be uniquely attributed to brp expression, whereas rbd expression augmented aggregate formation. Simultaneous expression of both loci led to the formation of a dramatic pellicle and maximum biofilm formation. Unlike the brp locus, transcription of the rbd locus was regulated not by c-di-GMP, but by a response regulator (RbdG) that was encoded within the locus. We propose that the ability to regulate the expression of polysaccharides with overlapping and unique characteristics in response to different environmental cues enables V. vulnificus to 'fine tune' its biofilm lifestyle to the prevailing environmental conditions and maximally benefit from the characteristics associated with each polysaccharide.
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Affiliation(s)
- Yunzhi Guo
- Department of Laboratory Medicine & Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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25
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Abstract
As an etiological agent of bacterial sepsis and wound infections, Vibrio vulnificus is unique among the Vibrionaceae. The most intensely studied of its virulence factors is the capsular polysaccharide (CPS). Over 100 CPS types have been identified, yet little is known about the genetic mechanisms that drive such diversity. Chitin, the second-most-abundant polysaccharide in nature, is known to induce competence in Vibrio species. Here, we show that the frequency of chitin-induced transformation in V. vulnificus varies by strain and that (GlcNAc)(2) is the shortest chitin-derived polymer capable of inducing competence. Transformation frequencies (TFs) increased 8-fold when mixed-culture biofilms were exposed to a strain-specific lytic phage, suggesting that the lysis of dead cells during lytic infection increased the amount of extracellular DNA within the biofilm that was available for transfer. Furthermore, we show that V. vulnificus can undergo chitin-dependent carbotype conversion following the uptake and recombination of complete cps loci from exogenous genomic DNA (gDNA). The acquisition of a partial locus was also demonstrated when internal regions of homology between the endogenous and exogenous loci existed. This suggested that the same mechanism governing the transfer of complete cps loci also contributed to their evolution by generating novel combinations of CPS biosynthesis genes. Since no evidence that cps loci were preferentially acquired during natural transformation (random transposon-tagged DNA was readily taken up in chitin transformation assays) exists, the phenomenon of chitin-induced transformation likely plays an important but general role in the evolution of this genetically promiscuous genus.
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Sathiyamoorthy K, Mills E, Franzmann TM, Rosenshine I, Saper MA. The crystal structure of Escherichia coli group 4 capsule protein GfcC reveals a domain organization resembling that of Wza. Biochemistry 2011; 50:5465-76. [PMID: 21449614 DOI: 10.1021/bi101869h] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the 1.9 Å resolution crystal structure of enteropathogenic Escherichia coli GfcC, a periplasmic protein encoded by the gfc operon, which is essential for assembly of group 4 polysaccharide capsule (O-antigen capsule). Presumed gene orthologs of gfcC are present in capsule-encoding regions of at least 29 genera of Gram-negative bacteria. GfcC, a member of the DUF1017 family, is comprised of tandem β-grasp (ubiquitin-like) domains (D2 and D3) and a carboxyl-terminal amphipathic helix, a domain arrangement reminiscent of that of Wza that forms an exit pore for group 1 capsule export. Unlike the membrane-spanning C-terminal helix from Wza, the GfcC C-terminal helix packs against D3. Previously unobserved in a β-grasp domain structure is a 48-residue helical hairpin insert in D2 that binds to D3, constraining its position and sequestering the carboxyl-terminal amphipathic helix. A centrally located and invariant Arg115 not only is essential for proper localization but also forms one of two mostly conserved pockets. Finally, we draw analogies between a GfcC protein fused to an outer membrane β-barrel pore in some species and fusion proteins necessary for secreting biofilm-forming exopolysaccharides.
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Chen Y, Dai J, Morris JG, Johnson JA. Genetic analysis of the capsule polysaccharide (K antigen) and exopolysaccharide genes in pandemic Vibrio parahaemolyticus O3:K6. BMC Microbiol 2010; 10:274. [PMID: 21044320 PMCID: PMC2987987 DOI: 10.1186/1471-2180-10-274] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Accepted: 11/02/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pandemic Vibrio parahaemolyticus has undergone rapid changes in both K- and O-antigens, making detection of outbreaks more difficult. In order to understand these rapid changes, the genetic regions encoding these antigens must be examined. In Vibrio cholerae and Vibrio vulnificus, both O-antigen and capsular polysaccharides are encoded in a single region on the large chromosome; a similar arrangement in pandemic V. parahaemolyticus would help explain the rapid serotype changes. However, previous reports on "capsule" genes are controversial. Therefore, we set out to clarify and characterize these regions in pandemic V. parahaemolyticus O3:K6 by gene deletion using a chitin based transformation strategy. RESULTS We generated different deletion mutants of putative polysaccharide genes and examined the mutants by immuno-blots with O and K specific antisera. Our results showed that O- and K-antigen genes are separated in V. parahaemolyticus O3:K6; the region encoding both O-antigen and capsule biosynthesis in other vibrios, i.e. genes between gmhD and rjg, determines the K6-antigen but not the O3-antigen in V. parahaemolyticus. The previously identified "capsule genes" on the smaller chromosome were related to exopolysaccharide synthesis, not K-antigen. CONCLUSION Understanding of the genetic basis of O- and K-antigens is critical to understanding the rapid changes in these polysaccharides seen in pandemic V. parahaemolyticus. This report confirms the genetic location of K-antigen synthesis in V. parahaemolyticus O3:K6 allowing us to focus future studies of the evolution of serotypes to this region.
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Affiliation(s)
- Yuansha Chen
- Department of Pathology, University of Florida, 1600 SW Archer Road, Gainesville, FL 32610, USA.
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Evidence for the horizontal transfer of an unusual capsular polysaccharide biosynthesis locus in marine bacteria. Infect Immun 2010; 78:5214-22. [PMID: 20921143 DOI: 10.1128/iai.00653-10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The most intensely studied of the Vibrio vulnificus virulence factors is the capsular polysaccharide (CPS). All virulent strains produce copious amounts of CPS. Acapsular strains are avirulent. The structure of the CPS from the clinical isolate ATCC 27562 is unusual. It is serine modified and contains, surprisingly, N-acetylmuramic acid. We identified the complete 25-kb CPS biosynthesis locus from ATCC 27562. It contained 21 open reading frames and was allelic to O-antigen biosynthesis loci. Two of the genes, murA(CPS) and murB(CPS), were paralogs of the murA(PG) and murB(PG) genes of the peptidoglycan biosynthesis pathway; only a single copy of these genes is present in the strain CMCP6 and YJ016 genomes. Although MurA(CPS) and MurB(CPS) were functional when expressed in Escherichia coli, lesions in either gene had no effect on CPS production, virulence, or growth in V. vulnificus; disruption of 8 other genes within the locus resulted in an acapsular phenotype and attenuated virulence. Thus, murA(CPS) and murB(CPS) were functional but redundant. Comparative genomic analysis revealed that while completely different CPS biosynthesis loci were found in the same chromosomal region in other V. vulnificus strains, most of the CPS locus of ATCC 27562 was conserved in another marine bacterium, Shewanella putrefaciens strain 200. However, the average GC content of the CPS locus was significantly lower than the average GC content of either genome. Furthermore, several of the encoded proteins appeared to be of Gram-positive and archaebacterial origin. These data indicate that the horizontal transfer of intact and partial CPS loci drives CPS diversity in marine bacteria.
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Apicella MA, Post DMB, Fowler AC, Jones BD, Rasmussen JA, Hunt JR, Imagawa S, Choudhury B, Inzana TJ, Maier TM, Frank DW, Zahrt TC, Chaloner K, Jennings MP, McLendon MK, Gibson BW. Identification, characterization and immunogenicity of an O-antigen capsular polysaccharide of Francisella tularensis. PLoS One 2010; 5:e11060. [PMID: 20625403 PMCID: PMC2897883 DOI: 10.1371/journal.pone.0011060] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 05/14/2010] [Indexed: 11/18/2022] Open
Abstract
Capsular polysaccharides are important factors in bacterial pathogenesis and have been the target of a number of successful vaccines. Francisella tularensis has been considered to express a capsular antigen but none has been isolated or characterized. We have developed a monoclonal antibody, 11B7, which recognizes the capsular polysaccharide of F. tularensis migrating on Western blot as a diffuse band between 100 kDa and 250 kDa. The capsule stains poorly on SDS-PAGE with silver stain but can be visualized using ProQ Emerald glycoprotein stain. The capsule appears to be highly conserved among strains of F. tularensis as antibody 11B7 bound to the capsule of 14 of 14 F. tularensis type A and B strains on Western blot. The capsular material can be isolated essentially free of LPS, is phenol and proteinase K resistant, ethanol precipitable and does not dissociate in sodium dodecyl sulfate. Immunoelectron microscopy with colloidal gold demonstrates 11B7 circumferentially staining the surface of F. tularensis which is typical of a polysaccharide capsule. Mass spectrometry, compositional analysis and NMR indicate that the capsule is composed of a polymer of the tetrasaccharide repeat, 4)-alpha-D-GalNAcAN-(1->4)-alpha-D-GalNAcAN-(1->3)-beta-D-QuiNAc-(1->2)-beta-D-Qui4NFm-(1-, which is identical to the previously described F. tularensis O-antigen subunit. This indicates that the F. tularensis capsule can be classified as an O-antigen capsular polysaccharide. Our studies indicate that F. tularensis O-antigen glycosyltransferase mutants do not make a capsule. An F. tularensis acyltransferase and an O-antigen polymerase mutant had no evidence of an O-antigen but expressed a capsular antigen. Passive immunization of BALB/c mice with 75 microg of 11B7 protected against a 150 fold lethal challenge of F. tularensis LVS. Active immunization of BALB/c mice with 10 microg of capsule showed a similar level of protection. These studies demonstrate that F. tularensis produces an O-antigen capsule that may be the basis of a future vaccine.
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Affiliation(s)
- Michael A Apicella
- Department of Microbiology, University of Iowa, Iowa City, Iowa, United States of America.
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Dahiya I, Stevenson RMW. Yersinia ruckeri genes that attenuate survival in rainbow trout (Oncorhynchus mykiss) are identified using signature-tagged mutants. Vet Microbiol 2010; 144:399-404. [PMID: 20202763 DOI: 10.1016/j.vetmic.2010.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 02/01/2010] [Accepted: 02/03/2010] [Indexed: 11/26/2022]
Abstract
To identify genes that enable the enteric redmouth disease bacterium, Yersinia ruckeri, to persist in salmonid fish, 1056 signature-tagged mini-Tn5Km2 transposon mutants of a serotype 1 strain of Y. ruckeri, RS1154, were screened in rainbow trout by immersion infection. Two rounds of screening in fish identified 25 mutants that were not re-isolated from the kidney, 7 days post-infection. Six mutants were tested a third time in fish, in 1:1 competitive challenges with the parent strain; 4 failed to establish in kidney and 2 were present at low levels compared to the parent. Sequence analyses from the single transposon insertion sites in each of the 25 mutants identified genes with sequence homologies to genes for ZnuA, a periplasmic zinc-binding protein of ZnuABC transporter; the UvrY response regulator of BarA-UvrY two-component system; a PtrA protease of the insulin-degrading enzyme family; the RcpA protein of type IV bundle-forming pili; the ParA ATPase of a ParAB DNA-partitioning system; a Wzy polymerase; a polysaccharide deacetylase; a transporter belonging to the major facilitator superfamily and 7 hypothetical proteins of unknown function. The products of 5 of these mutated genes have predicted functions associated with cell surfaces or membranes, which could be important for survival of Y. ruckeri in rainbow trout, while other putative gene products could contribute to infection and invasion processes.
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Affiliation(s)
- Indervesh Dahiya
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, N1G 2W1, ON, Canada
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Identification of a c-di-GMP-regulated polysaccharide locus governing stress resistance and biofilm and rugose colony formation in Vibrio vulnificus. Infect Immun 2010; 78:1390-402. [PMID: 20065022 DOI: 10.1128/iai.01188-09] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
As an etiological agent of bacterial sepsis and wound infections, Vibrio vulnificus is unique among the Vibrionaceae. Its continued environmental persistence and transmission are bolstered by its ability to colonize shellfish, form biofilms on various marine biotic surfaces, and generate a morphologically and physiologically distinct rugose (R) variant that yields profuse biofilms. Here, we identify a c-di-GMP-regulated locus (brp, for biofilm and rugose polysaccharide) and two transcription factors (BrpR and BrpT) that regulate these physiological responses. Disruption of glycosyltransferases within the locus or either regulator abated the inducing effect of c-di-GMP on biofilm formation, rugosity, and stress resistance. The same lesions, or depletion of intracellular c-di-GMP levels, abrogated these phenotypes in the R variant. The parental and brp mutant strains formed only scant monolayers on glass surfaces and oyster shells, and although the R variant formed expansive biofilms, these were of limited depth. Dramatic vertical expansion of the biofilm structure was observed in the parental strain and R variant, but not the brp mutants, when intracellular c-di-GMP levels were elevated. Hence, the brp-encoded polysaccharide is important for surface colonization and stress resistance in V. vulnificus, and its expression may control how the bacteria switch from a planktonic lifestyle to colonizing shellfish to invading human tissue.
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Shu HY, Fung CP, Liu YM, Wu KM, Chen YT, Li LH, Liu TT, Kirby R, Tsai SF. Genetic diversity of capsular polysaccharide biosynthesis in Klebsiella pneumoniae clinical isolates. MICROBIOLOGY-SGM 2009; 155:4170-4183. [PMID: 19744990 DOI: 10.1099/mic.0.029017-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Klebsiella pneumoniae is an enteric pathogen causing community-acquired and hospital-acquired infections in humans. Epidemiological studies have revealed significant diversity in capsular polysaccharide (CPS) type and clinical manifestation of K. pneumoniae infection in different geographical areas of the world. We have sequenced the capsular polysaccharide synthesis (cps) region of seven clinical isolates and compared the sequences with the publicly available cps sequence data of five strains: NTUH-K2044 (K1 serotype), Chedid (K2 serotype), MGH78578 (K52 serotype), A1142 (K57 serotype) and A1517. Among all strains, six genes at the 5' end of the cps clusters that encode proteins for CPS transportation and processing at the bacterial surface are highly similar to each other. The central region of the cps gene clusters, which encodes proteins for polymerization and assembly of the CPS subunits, is highly divergent. Based on the collected sequence, we found that either the wbaP gene or the wcaJ gene exists in a given K. pneumoniae strain, suggesting that there is a major difference in the CPS biosynthesis pathway and that the K. pneumoniae strains can be classified into at least two distinct groups. All isolates contain gnd, encoding gluconate-6-phosphate dehydrogenase, at the 3' end of the cps gene clusters. The rmlBADC genes were found in CPS K9-positive, K14-positive and K52-positive strains, while manC and manB were found in K1, K2, K5, K14, K62 and two undefined strains. Our data indicate that, while overall genomic organization is similar between different pathogenic K. pneumoniae strains, the genetic variation of the sugar moiety and polysaccharide linkage generate the diversity in CPS molecules that could help evade host immune attack.
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Affiliation(s)
- Hung-Yu Shu
- Genome Research Center, National Yang-Ming University, Taipei, Taiwan, ROC.,Department of Bioscience Technology, Chang Jung Christian University, Tainan County, Taiwan, ROC
| | - Chang-Phone Fung
- Institute of Tropical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC.,Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Yen-Ming Liu
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, ROC
| | - Keh-Ming Wu
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan, ROC.,Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, ROC
| | - Ying-Tsong Chen
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, ROC
| | - Ling-Hui Li
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, ROC
| | - Tze-Tze Liu
- Genome Research Center, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Ralph Kirby
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Shih-Feng Tsai
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan, ROC.,Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, ROC.,Genome Research Center, National Yang-Ming University, Taipei, Taiwan, ROC.,Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan, ROC
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Kim HS, Park SJ, Lee KH. Role of NtrC-regulated exopolysaccharides in the biofilm formation and pathogenic interaction of Vibrio vulnificus. Mol Microbiol 2009; 74:436-53. [PMID: 19737353 DOI: 10.1111/j.1365-2958.2009.06875.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vibrio vulnificus has been shown to require a global transcription factor, NtrC for mature biofilm development via controlling the biosyntheses of lipopolysaccharide and exopolysaccharide (EPS). Biofilm formation and EPS production were dramatically increased in a medium including a tricarboxylic acid cycle-intermediate as a carbon source. These phenotypes required functional NtrC and were abolished by the addition of ammonium chloride. During the initial stage of biofilm formation, both expression of the ntrC gene and the cellular content of NtrC protein increased. Thus, the regulatory roles of NtrC in EPS biosynthesis were studied with three gene clusters for EPS biosyntheses. Transcriptions of the three clusters were positively controlled by NtrC and showed maximal expression at the early stage of biofilm development. Mutants deficient in one of the genes (VV1_2661, VV2_1579 and VV1_2305) in each cluster showed decreased production of EPS, attenuated ability to form biofilm and lowered cytoadherence to human epithelial cells. However, mutations in VV2_1579 and VV1_2305 resulted in lower cytotoxicity to human cells and mortality to mice than the mutation in VV1_2661. These results demonstrate that NtrC-regulated EPS are crucial in biofilm formation of V. vulnificus, and some EPS components play important roles in interacting with hosts.
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Affiliation(s)
- Han-Suk Kim
- Department of Environmental Science and Protein Research Center for Bio-Industry, Hankuk University of Foreign Studies, Yongin, Kyunggi-Do 449-791, South Korea
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Paramonov NA, Aduse-Opoku J, Hashim A, Rangarajan M, Curtis MA. Structural analysis of the core region of O-lipopolysaccharide of Porphyromonas gingivalis from mutants defective in O-antigen ligase and O-antigen polymerase. J Bacteriol 2009; 191:5272-82. [PMID: 19525343 PMCID: PMC2725592 DOI: 10.1128/jb.00019-09] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Accepted: 06/02/2009] [Indexed: 11/20/2022] Open
Abstract
Porphyromonas gingivalis synthesizes two lipopolysaccharides (LPSs), O-LPS and A-LPS. Here, we elucidate the structure of the core oligosaccharide (OS) of O-LPS from two mutants of P. gingivalis W50, Delta PG1051 (WaaL, O-antigen ligase) and Delta PG1142 (O-antigen polymerase), which synthesize R-type LPS (core devoid of O antigen) and SR-type LPS (core plus one repeating unit of O antigen), respectively. Structural analyses were performed using one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy in combination with composition and methylation analysis. The outer core OS of O-LPS occurs in two glycoforms: an "uncapped core," which is devoid of O polysaccharide (O-PS), and a "capped core," which contains the site of O-PS attachment. The inner core region lacks L(D)-glycero-D(l)-manno-heptosyl residues and is linked to the outer core via 3-deoxy-D-manno-octulosonic acid, which is attached to a glycerol residue in the outer core via a monophosphodiester bridge. The outer region of the "uncapped core" is attached to the glycerol and is composed of a linear alpha-(1-->3)-linked d-Man OS containing four or five mannopyranosyl residues, one-half of which are modified by phosphoethanolamine at position 6. An amino sugar, alpha-D-allosamine, is attached to the glycerol at position 3. In the "capped core," there is a three- to five-residue extension of alpha-(1-->3)-linked Man residues glycosylating the outer core at the nonreducing terminal residue. beta-D-GalNAc from the O-PS repeating unit is attached to the nonreducing terminal Man at position 3. The core OS of P. gingivalis O-LPS is therefore a highly unusual structure, and it is the basis for further investigation of the mechanism of assembly of the outer membrane of this important periodontal bacterium.
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Affiliation(s)
- Nikolay A Paramonov
- Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Centre for Infectious Disease, Institute of Cell and Molecular Science, 4 Newark Street, London E1 2AT, United Kingdom
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Vibrio biofilms: so much the same yet so different. Trends Microbiol 2009; 17:109-18. [PMID: 19231189 DOI: 10.1016/j.tim.2008.12.004] [Citation(s) in RCA: 328] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 11/11/2008] [Accepted: 12/05/2008] [Indexed: 12/20/2022]
Abstract
Vibrios are natural inhabitants of aquatic environments and form symbiotic or pathogenic relationships with eukaryotic hosts. Recent studies reveal that the ability of vibrios to form biofilms (i.e. matrix-enclosed, surface-associated communities) depends upon specific structural genes (flagella, pili and exopolysaccharide biosynthesis) and regulatory processes (two-component regulators, quorum sensing and c-di-GMP signaling). Here, we compare and contrast mechanisms and regulation of biofilm formation by Vibrio species, with a focus on Vibrio cholerae, Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio fischeri. Although many aspects are the same, others differ dramatically. Crucial questions that remain to be answered regarding the molecular underpinnings of Vibrio biofilm formation are also discussed.
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Characterization of the Caulobacter crescentus holdfast polysaccharide biosynthesis pathway reveals significant redundancy in the initiating glycosyltransferase and polymerase steps. J Bacteriol 2008; 190:7219-31. [PMID: 18757530 DOI: 10.1128/jb.01003-08] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Caulobacter crescentus cells adhere to surfaces by using an extremely strong polar adhesin called the holdfast. The polysaccharide component of the holdfast is comprised in part of oligomers of N-acetylglucosamine. The genes involved in the export of the holdfast polysaccharide and the anchoring of the holdfast to the cell were previously discovered. In this study, we identified a cluster of polysaccharide biosynthesis genes (hfsEFGH) directly adjacent to the holdfast polysaccharide export genes. Sequence analysis indicated that these genes are involved in the biosynthesis of the minimum repeat unit of the holdfast polysaccharide. HfsE is predicted to be a UDP-sugar lipid-carrier transferase, the glycosyltransferase that catalyzes the first step in polysaccharide biosynthesis. HfsF is predicted to be a flippase, HfsG is a glycosyltransferase, and HfsH is similar to a polysaccharide (chitin) deacetylase. In-frame hfsG and hfsH deletion mutants resulted in severe deficiencies both in surface adhesion and in binding to the holdfast-specific lectin wheat germ agglutinin. In contrast, hfsE and hfsF mutants exhibited nearly wild-type levels of adhesion and holdfast synthesis. We identified three paralogs to hfsE, two of which are redundant to hfsE for holdfast synthesis. We also identified a redundant paralog to the hfsC gene, encoding the putative polysaccharide polymerase, and present evidence that the hfsE and hfsC paralogs, together with the hfs genes, are absolutely required for proper holdfast synthesis.
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Cyclic-di-GMP regulates extracellular polysaccharide production, biofilm formation, and rugose colony development by Vibrio vulnificus. Appl Environ Microbiol 2008; 74:4199-209. [PMID: 18487410 DOI: 10.1128/aem.00176-08] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Vibrio vulnificus is a human and animal pathogen that carries the highest death rate of any food-borne disease agent. It colonizes shellfish and forms biofilms on the surfaces of plankton, algae, fish, and eels. Greater understanding of biofilm formation by the organism could provide insight into approaches to decrease its load in filter feeders and on biotic surfaces and control the occurrence of invasive disease. The capsular polysaccharide (CPS), although essential for virulence, is not required for biofilm formation under the conditions used here. In other bacteria, increased biofilm formation often correlates with increased exopolysaccharide (EPS) production. We exploited the translucent phenotype of acapsular mutants to screen a V. vulnificus genomic library and identify genes that imparted an opaque phenotype to both CPS biosynthesis and transport mutants. One of these encoded a diguanylate cyclase (DGC), an enzyme that synthesizes bis-(3'-5')-cyclic-di-GMP (c-di-GMP). This prompted us to use this DGC, DcpA, to examine the effect of elevated c-di-GMP levels on several developmental pathways in V. vulnificus. Increased c-di-GMP levels induced the production of an EPS that was distinct from the CPS and dramatically enhanced biofilm formation and rugosity in a CPS-independent manner. However, the EPS could not compensate for the loss of CPS production that is required for virulence. In contrast to V. cholerae, motility and virulence appeared unaffected by elevated levels of c-di-GMP.
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