1
|
Xu Z, Li Y, Xu A, Soteyome T, Yuan L, Ma Q, Seneviratne G, Li X, Liu J. Cell-wall-anchored proteins affect invasive host colonization and biofilm formation in Staphylococcus aureus. Microbiol Res 2024; 285:127782. [PMID: 38833832 DOI: 10.1016/j.micres.2024.127782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Revised: 05/21/2024] [Accepted: 05/21/2024] [Indexed: 06/06/2024]
Abstract
As a major human and animal pathogen, Staphylococcus aureus can attach to medical implants (abiotic surface) or host tissues (biotic surface), and further establish robust biofilms which enhances resistance and persistence to host immune system and antibiotics. Cell-wall-anchored proteins (CWAPs) covalently link to peptidoglycan, and largely facilitate the colonization of S. aureus on various surfaces (including adhesion and biofilm formation) and invasion into host cells (including adhesion, immune evasion, iron acquisition and biofilm formation). During biofilm formation, CWAPs function in adhesion, aggregation, collagen-like fiber network formation, and consortia formation. In this review, we firstly focus on the structural features of CWAPs, including their intracellular function and interactions with host cells, as well as the functions and ligand binding of CWAPs in different stages of S. aureus biofilm formation. Then, the roles of CWAPs in different biofilm processes with regards in development of therapeutic approaches are clarified, followed by the association between CWAPs genes and clonal lineages. By touching upon these aspects, we hope to provide comprehensive knowledge and clearer understanding on the CWAPs of S. aureus and their roles in biofilm formation, which may further aid in prevention and treatment infection and vaccine development.
Collapse
Affiliation(s)
- Zhenbo Xu
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Engineering Research Center of Starch and Vegetable Protein Processing Ministry of Education, South China University of Technology, Guangzhou 510640, China; Department of Laboratory Medicine, the Second Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China.
| | - Yaqin Li
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Engineering Research Center of Starch and Vegetable Protein Processing Ministry of Education, South China University of Technology, Guangzhou 510640, China
| | - Aijuan Xu
- Guangzhou Hybribio Medical Laboratory, Guangzhou 510730, China
| | - Thanapop Soteyome
- Home Economics Technology, Rajamangala University of Technology Phra Nakhon, Bangkok, Thailand
| | - Lei Yuan
- School of Food Science and Engineering, Yangzhou University, Yangzhou, Jiangsu 225127, China
| | - Qin Ma
- Sericultural & Agri-Food Research Institute Guangdong Academy of Agricultural Sciences/Key Laboratory of Functional Foods, Ministry of Agriculture /Guangdong Key Laboratory of Agricultural Products Processing, Guangzhou 510610, China
| | - Gamini Seneviratne
- National Institute of Fundamental Studies, Hantana road, Kandy, Sri Lanka
| | - Xuejie Li
- School of Food Science and Engineering, Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Engineering Research Center of Starch and Vegetable Protein Processing Ministry of Education, South China University of Technology, Guangzhou 510640, China.
| | - Junyan Liu
- College of Light Industry and Food Science, Guangdong Provincial Key Laboratory of Lingnan Specialty Food Science and Technology, Academy of Contemporary Agricultural Engineering Innovations, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China; Key Laboratory of Green Processing and Intelligent Manufacturing of Lingnan Specialty Food, Ministry of Agriculture, Guangzhou 510225, China.
| |
Collapse
|
2
|
Dong J, Zhang Y, Yang Q, Liu Y, Zhou S, Ai X. Fraxetin Targeting to Sortase A Decreases the Pathogenicity of Streptococcus agalactiae to Nile Tilapia. Animals (Basel) 2024; 14:1337. [PMID: 38731341 PMCID: PMC11083127 DOI: 10.3390/ani14091337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 04/09/2024] [Accepted: 04/27/2024] [Indexed: 05/13/2024] Open
Abstract
Sortase A (SrtA) is responsible for anchoring surface proteins to the cell wall, and has been identified as a promising target developing anti-infective drugs of Gram-positive bacteria. The aim of the study was to identify inhibitors of Streptococcus agalactiae (S. agalactiae) SrtA from natural compounds to overcome the spread of antibiotic resistance in aquaculture. Here, we found that the MIC of fraxetin against S. agalactiae was higher than 256 μg/mL, indicating that fraxetin had no anti- S. agalactiae activity. But fraxetin could dose-dependently decrease the activity of SrtA in vitro at concentrations ranging between 4-32 μg/mL by a fluorescence resonance energy transfer (FRET) assay. Moreover, the inhibition of SrtA by fraxetin decreased the anchoring of surface proteins with the LPXTG motif to the cell wall by detecting the immunofluorescence change of serine-rich repeat protein 1 (Srr1) on the bacterial cell surface. The results of fibronectin binding and cell adhesion assays indicated that fraxetin could significantly decrease the adhesion ability of S. agalactiae in a dose-dependent manner. The results were further proven by immunofluorescence staining. Animal challenge results showed that treatment with fraxetin could reduce the mortality of tilapia infected with S. agalactiae to 46.67%, indicating that fraxetin could provide a significant amount of protection to tilapia by inactivating SrtA. Taken together, these findings provided a novel inhibitor of S. agalactiae SrtA and a promising candidate for treating S. agalactiae infections in aquaculture.
Collapse
Affiliation(s)
- Jing Dong
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Yuze Zhang
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
- College of Food Science and Engineering, Bohai University, Jinzhou 121010, China
| | - Qiuhong Yang
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Yongtao Liu
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Shun Zhou
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Xiaohui Ai
- Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| |
Collapse
|
3
|
Cinar MS, Niyas A, Avci FY. Serine-rich repeat proteins: well-known yet little-understood bacterial adhesins. J Bacteriol 2024; 206:e0024123. [PMID: 37975670 PMCID: PMC10810200 DOI: 10.1128/jb.00241-23] [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] [Indexed: 11/19/2023] Open
Abstract
Serine-rich-repeat proteins (SRRPs) are large mucin-like glycoprotein adhesins expressed by a plethora of pathogenic and symbiotic Gram-positive bacteria. SRRPs play major functional roles in bacterial-host interactions, like adhesion, aggregation, biofilm formation, virulence, and pathogenesis. Through their functional roles, SRRPs aid in the development of host microbiomes but also diseases like infective endocarditis, otitis media, meningitis, and pneumonia. SRRPs comprise shared domains across different species, including two or more heavily O-glycosylated long stretches of serine-rich repeat regions. With loci that can be as large as ~40 kb and can encode up to 10 distinct glycosyltransferases that specifically facilitate SRRP glycosylation, the SRRP loci makes up a significant portion of the bacterial genome. The significance of SRRPs and their glycans in host-microbe communications is becoming increasingly evident. Studies are beginning to reveal the glycosylation pathways and mature O-glycans presented by SRRPs. Here we review the glycosylation machinery of SRRPs across species and discuss the functional roles and clinical manifestations of SRRP glycosylation.
Collapse
Affiliation(s)
- Mukaddes S. Cinar
- Department of Biochemistry, Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Afaq Niyas
- Department of Biochemistry, Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Fikri Y. Avci
- Department of Biochemistry, Emory Vaccine Center, Emory University School of Medicine, Atlanta, Georgia, USA
| |
Collapse
|
4
|
Moore R, Spicer SK, Lu J, Chambers SA, Noble KN, Lochner J, Christofferson RC, Vasco KA, Manning SD, Townsend SD, Gaddy JA. The Utility of Human Milk Oligosaccharides against Group B Streptococcus Infections of Reproductive Tissues and Cognate Adverse Pregnancy Outcomes. ACS CENTRAL SCIENCE 2023; 9:1737-1749. [PMID: 37780357 PMCID: PMC10540283 DOI: 10.1021/acscentsci.3c00101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Indexed: 10/03/2023]
Abstract
Preterm birth affects nearly 10% of all pregnancies in the United States, with 40% of those due, in part, to infections. Streptococcus agalactiae (Group B Streptococcus, GBS) is one of the most common perinatal pathogens responsible for these infections. Current therapeutic techniques aimed to ameliorate invasive GBS infections are less than desirable and can result in complications in both the neonate and the mother. To this end, the need for novel therapeutic options is urgent. Human milk oligosaccharides (HMOs), an integral component of human breast milk, have been previously shown to possess antiadhesive and antimicrobial properties. To interrogate these characteristics, we examined HMO-mediated outcomes in both in vivo and ex vivo models of GBS infection utilizing a murine model of ascending GBS infection, an EpiVaginal human organoid tissue model, and ex vivo human gestational membranes. Supplementation of HMOs resulted in diminished adverse pregnancy outcomes, decreased GBS adherence to gestational tissues, decreased colonization within the reproductive tract, and reduced proinflammatory immune responses to GBS infection. Taken together, these results highlight the potential of HMOs as promising therapeutic interventions in perinatal health.
Collapse
Affiliation(s)
- Rebecca
E. Moore
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
- Department of Veterans Affairs, Tennessee
Valley Healthcare Systems, Nashville, Tennessee 37212, United States
| | - Sabrina K. Spicer
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Jacky Lu
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Schuyler A. Chambers
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Kristen N. Noble
- Department
of Pediatrics, Vanderbilt University Medical
Center, Nashville, Tennessee 37232, United States
| | - Jonathan Lochner
- Department
of Pediatrics, Vanderbilt University Medical
Center, Nashville, Tennessee 37232, United States
| | - Rebecca C. Christofferson
- Department of Pathobiological
Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Karla A. Vasco
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Shannon D. Manning
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Steven D. Townsend
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Jennifer A. Gaddy
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
- Department of Veterans Affairs, Tennessee
Valley Healthcare Systems, Nashville, Tennessee 37212, United States
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| |
Collapse
|
5
|
Group B Streptococcus: Virulence Factors and Pathogenic Mechanism. Microorganisms 2022; 10:microorganisms10122483. [PMID: 36557736 PMCID: PMC9784991 DOI: 10.3390/microorganisms10122483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 12/10/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Group B Streptococcus (GBS) or Streptococcus agalactiae is a major cause of neonatal mortality. When colonizing the lower genital tract of pregnant women, GBS may cause premature birth and stillbirth. If transmitted to the newborn, it may result in life-threatening illnesses, including sepsis, meningitis, and pneumonia. Moreover, through continuous evolution, GBS can use its original structure and unique factors to greatly improve its survival rate in the human body. This review discusses the key virulence factors that facilitate GBS invasion and colonization and their action mechanisms. A comprehensive understanding of the role of virulence factors in GBS infection is crucial to develop better treatment options and screen potential candidate molecules for the development of the vaccine.
Collapse
|
6
|
Pellegrini A, Lentini G, Famà A, Bonacorsi A, Scoffone VC, Buroni S, Trespidi G, Postiglione U, Sassera D, Manai F, Pietrocola G, Firon A, Biondo C, Teti G, Beninati C, Barbieri G. CodY Is a Global Transcriptional Regulator Required for Virulence in Group B Streptococcus. Front Microbiol 2022; 13:881549. [PMID: 35572655 PMCID: PMC9096947 DOI: 10.3389/fmicb.2022.881549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 03/21/2022] [Indexed: 12/03/2022] Open
Abstract
Group B Streptococcus (GBS) is a Gram-positive bacterium able to switch from a harmless commensal of healthy adults to a pathogen responsible for invasive infections in neonates. The signals and regulatory mechanisms governing this transition are still largely unknown. CodY is a highly conserved global transcriptional regulator that links nutrient availability to the regulation of major metabolic and virulence pathways in low-G+C Gram-positive bacteria. In this work, we investigated the role of CodY in BM110, a GBS strain representative of a hypervirulent lineage associated with the majority of neonatal meningitis. Deletion of codY resulted in a reduced ability of the mutant strain to cause infections in neonatal and adult animal models. The observed decreased in vivo lethality was associated with an impaired ability of the mutant to persist in the blood, spread to distant organs, and cross the blood-brain barrier. Notably, the codY null mutant showed reduced adhesion to monolayers of human epithelial cells in vitro and an increased ability to form biofilms, a phenotype associated with strains able to asymptomatically colonize the host. RNA-seq analysis showed that CodY controls about 13% of the genome of GBS, acting mainly as a repressor of genes involved in amino acid transport and metabolism and encoding surface anchored proteins, including the virulence factor Srr2. CodY activity was shown to be dependent on the availability of branched-chain amino acids, which are the universal cofactors of this regulator. These results highlight a key role for CodY in the control of GBS virulence.
Collapse
Affiliation(s)
- Angelica Pellegrini
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Germana Lentini
- Department of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Agata Famà
- Department of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Andrea Bonacorsi
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Viola Camilla Scoffone
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Silvia Buroni
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Gabriele Trespidi
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Umberto Postiglione
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Davide Sassera
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Federico Manai
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | | | - Arnaud Firon
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Unité Biologie des Bactéries Pathogènes à Gram-positif, Paris, France
| | - Carmelo Biondo
- Department of Human Pathology and Medicine, University of Messina, Messina, Italy
| | | | - Concetta Beninati
- Department of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Giulia Barbieri
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| |
Collapse
|
7
|
Abstract
Post-translational modification with O-linked β-N-acetylglucosamine (O-GlcNAc), a process referred to as O-GlcNAcylation, occurs on a vast variety of proteins. Mounting evidence in the past several decades has clearly demonstrated that O-GlcNAcylation is a unique and ubiquitous modification. Reminiscent of a code, protein O-GlcNAcylation functions as a crucial regulator of nearly all cellular processes studied. The primary aim of this review is to summarize the developments in our understanding of myriad protein substrates modified by O-GlcNAcylation from a systems perspective. Specifically, we provide a comprehensive survey of O-GlcNAcylation in multiple species studied, including eukaryotes (e.g., protists, fungi, plants, Caenorhabditis elegans, Drosophila melanogaster, murine, and human), prokaryotes, and some viruses. We evaluate features (e.g., structural properties and sequence motifs) of O-GlcNAc modification on proteins across species. Given that O-GlcNAcylation functions in a species-, tissue-/cell-, protein-, and site-specific manner, we discuss the functional roles of O-GlcNAcylation on human proteins. We focus particularly on several classes of relatively well-characterized human proteins (including transcription factors, protein kinases, protein phosphatases, and E3 ubiquitin-ligases), with representative O-GlcNAc site-specific functions presented. We hope the systems view of the great endeavor in the past 35 years will help demystify the O-GlcNAc code and lead to more fascinating studies in the years to come.
Collapse
Affiliation(s)
- Junfeng Ma
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Georgetown University, Washington, DC 20057, United States
| | - Chunyan Hou
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Georgetown University, Washington, DC 20057, United States
| | - Ci Wu
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Georgetown University, Washington, DC 20057, United States
| |
Collapse
|
8
|
Brokaw A, Furuta A, Dacanay M, Rajagopal L, Adams Waldorf KM. Bacterial and Host Determinants of Group B Streptococcal Vaginal Colonization and Ascending Infection in Pregnancy. Front Cell Infect Microbiol 2021; 11:720789. [PMID: 34540718 PMCID: PMC8446444 DOI: 10.3389/fcimb.2021.720789] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 08/09/2021] [Indexed: 12/17/2022] Open
Abstract
Group B streptococcus (GBS) is a gram-positive bacteria that asymptomatically colonizes the vaginal tract. However, during pregnancy maternal GBS colonization greatly predisposes the mother and baby to a wide range of adverse outcomes, including preterm birth (PTB), stillbirth, and neonatal infection. Although many mechanisms involved in GBS pathogenesis are partially elucidated, there is currently no approved GBS vaccine. The development of a safe and effective vaccine that can be administered during or prior to pregnancy remains a principal objective in the field, because current antibiotic-based therapeutic strategies do not eliminate all cases of invasive GBS infections. Herein, we review our understanding of GBS disease pathogenesis at the maternal-fetal interface with a focus on the bacterial virulence factors and host defenses that modulate the outcome of infection. We follow GBS along its path from an asymptomatic colonizer of the vagina to an invasive pathogen at the maternal-fetal interface, noting factors critical for vaginal colonization, ascending infection, and vertical transmission to the fetus. Finally, at each stage of infection we emphasize important host-pathogen interactions, which, if targeted therapeutically, may help to reduce the global burden of GBS.
Collapse
Affiliation(s)
- Alyssa Brokaw
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, United States.,Department of Global Health, University of Washington, Seattle, WA, United States
| | - Anna Furuta
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, United States.,Department of Global Health, University of Washington, Seattle, WA, United States
| | - Matthew Dacanay
- Department of Obstetrics & Gynecology, University of Washington, Seattle, WA, United States
| | - Lakshmi Rajagopal
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, United States.,Department of Global Health, University of Washington, Seattle, WA, United States.,Department of Pediatrics, University of Washington, Seattle, WA, United States
| | - Kristina M Adams Waldorf
- Department of Global Health, University of Washington, Seattle, WA, United States.,Department of Obstetrics & Gynecology, University of Washington, Seattle, WA, United States.,Department of Obstetrics and Gynecology, University of Washington and Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| |
Collapse
|
9
|
Mazzuoli MV, Daunesse M, Varet H, Rosinski-Chupin I, Legendre R, Sismeiro O, Gominet M, Kaminski PA, Glaser P, Chica C, Trieu-Cuot P, Firon A. The CovR regulatory network drives the evolution of Group B Streptococcus virulence. PLoS Genet 2021; 17:e1009761. [PMID: 34491998 PMCID: PMC8448333 DOI: 10.1371/journal.pgen.1009761] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 09/17/2021] [Accepted: 08/09/2021] [Indexed: 01/31/2023] Open
Abstract
Virulence of the neonatal pathogen Group B Streptococcus is under the control of the master regulator CovR. Inactivation of CovR is associated with large-scale transcriptome remodeling and impairs almost every step of the interaction between the pathogen and the host. However, transcriptome analyses suggested a plasticity of the CovR signaling pathway in clinical isolates leading to phenotypic heterogeneity in the bacterial population. In this study, we characterized the CovR regulatory network in a strain representative of the CC-17 hypervirulent lineage responsible of the majority of neonatal meningitis. Transcriptome and genome-wide binding analysis reveal the architecture of the CovR network characterized by the direct repression of a large array of virulence-associated genes and the extent of co-regulation at specific loci. Comparative functional analysis of the signaling network links strain-specificities to the regulation of the pan-genome, including the two specific hypervirulent adhesins and horizontally acquired genes, to mutations in CovR-regulated promoters, and to variability in CovR activation by phosphorylation. This regulatory adaptation occurs at the level of genes, promoters, and of CovR itself, and allows to globally reshape the expression of virulence genes. Overall, our results reveal the direct, coordinated, and strain-specific regulation of virulence genes by the master regulator CovR and suggest that the intra-species evolution of the signaling network is as important as the expression of specific virulence factors in the emergence of clone associated with specific diseases. Streptococcus agalactiae, commonly known as the Group B Streptococcus (GBS), is a commensal bacterium of the intestinal and vaginal tracts found in approximately 30% of healthy adults. However, GBS is also an opportunistic pathogen and the leading cause of neonatal invasive infections. Epidemiologic data have identified a particular GBS clone, designated the CC-17 hypervirulent clonal complex, as responsible for the overwhelming majority of neonatal meningitis. The hypervirulence of CC-17 has been linked to the expression of two specific surface proteins increasing their abilities to cross epithelial and endothelial barriers. In this study, we characterized the role of the major regulator of virulence gene expression, the CovR response regulator, in a representative hypervirulent strain. Transcriptome and genome-wide binding analysis reveal the architecture of the CovR signaling network characterized by the direct repression of a large array of virulence-associated genes, including the specific hypervirulent adhesins. Comparative analysis in a non-CC-17 wild type strain demonstrates a high level of plasticity of the regulatory network, allowing to globally reshape pathogen-host interaction. Overall, our results suggest that the intra-species evolution of the regulatory network is an important factor in the emergence of GBS clones associated with specific pathologies.
Collapse
Affiliation(s)
- Maria-Vittoria Mazzuoli
- Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS UMR2001 Microbiologie Intégrative et Moléculaire, Institut Pasteur, Paris, France
- Sorbonne Paris Cité, Université de Paris, Paris, France
| | - Maëlle Daunesse
- Hub de Bioinformatique et Biostatistique—Département Biologie Computationnelle, Institut Pasteur, Paris, France
| | - Hugo Varet
- Hub de Bioinformatique et Biostatistique—Département Biologie Computationnelle, Institut Pasteur, Paris, France
- Plate-forme Technologique Biomics—Centre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, Paris, France
| | - Isabelle Rosinski-Chupin
- Unité Écologie et Évolution de la Résistance aux Antibiotiques, CNRS UMR3525, Institut Pasteur, Paris, France
| | - Rachel Legendre
- Hub de Bioinformatique et Biostatistique—Département Biologie Computationnelle, Institut Pasteur, Paris, France
- Plate-forme Technologique Biomics—Centre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, Paris, France
| | - Odile Sismeiro
- Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS UMR2001 Microbiologie Intégrative et Moléculaire, Institut Pasteur, Paris, France
- Plate-forme Technologique Biomics—Centre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, Paris, France
| | - Myriam Gominet
- Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS UMR2001 Microbiologie Intégrative et Moléculaire, Institut Pasteur, Paris, France
| | - Pierre Alexandre Kaminski
- Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS UMR2001 Microbiologie Intégrative et Moléculaire, Institut Pasteur, Paris, France
| | - Philippe Glaser
- Unité Écologie et Évolution de la Résistance aux Antibiotiques, CNRS UMR3525, Institut Pasteur, Paris, France
| | - Claudia Chica
- Hub de Bioinformatique et Biostatistique—Département Biologie Computationnelle, Institut Pasteur, Paris, France
| | - Patrick Trieu-Cuot
- Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS UMR2001 Microbiologie Intégrative et Moléculaire, Institut Pasteur, Paris, France
| | - Arnaud Firon
- Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS UMR2001 Microbiologie Intégrative et Moléculaire, Institut Pasteur, Paris, France
- * E-mail:
| |
Collapse
|
10
|
Whole genome sequencing reveals possible host species adaptation of Streptococcus dysgalactiae. Sci Rep 2021; 11:17350. [PMID: 34462475 PMCID: PMC8405622 DOI: 10.1038/s41598-021-96710-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 08/13/2021] [Indexed: 11/08/2022] Open
Abstract
Streptococcus dysgalactiae (SD) is an emerging pathogen in human and veterinary medicine, and is associated with several host species, disease phenotypes and virulence mechanisms. SD has traditionally been divided into the subspecies dysgalactiae (SDSD) and subsp. equisimilis (SDSE), but recent molecular studies have indicated that the phylogenetic relationships are more complex. Moreover, the genetic basis for the niche versatility of SD has not been extensively investigated. To expand the knowledge about virulence factors, phylogenetic relationships and host-adaptation strategies of SD, we analyzed 78 SDSD genomes from cows and sheep, and 78 SDSE genomes from other host species. Sixty SDSD and 40 SDSE genomes were newly sequenced in this study. Phylogenetic analysis supported SDSD as a distinct taxonomic entity, presenting a mean value of the average nucleotide identity of 99%. Bovine and ovine associated SDSD isolates clustered separately on pangenome analysis, but no single gene or genetic region was uniquely associated with host species. In contrast, SDSE isolates were more heterogenous and could be delineated in accordance with host. Although phylogenetic clustering suggestive of cross species transmission was observed, we predominantly detected a host restricted distribution of the SD-lineages. Furthermore, lineage specific virulence factors were detected, several of them located in proximity to hotspots for integration of mobile genetic elements. Our study indicates that SD has evolved to adapt to several different host species and infers a potential role of horizontal genetic transfer in niche specialization.
Collapse
|
11
|
Functional Insights into the High-Molecular-Mass Penicillin-Binding Proteins of Streptococcus agalactiae Revealed by Gene Deletion and Transposon Mutagenesis Analysis. J Bacteriol 2021; 203:e0023421. [PMID: 34124943 DOI: 10.1128/jb.00234-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
High-molecular-mass penicillin-binding proteins (PBPs) are enzymes that catalyze the biosynthesis of bacterial cell wall peptidoglycan. The Gram-positive bacterial pathogen Streptococcus agalactiae (group B streptococcus [GBS]) produces five high-molecular-mass PBPs, namely, PBP1A, PBP1B, PBP2A, PBP2B, and PBP2X. Among these, only PBP2X is essential for cell viability, whereas the other four PBPs are individually dispensable. The biological function of the four nonessential PBPs is poorly characterized in GBS. We deleted the pbp1a, pbp1b, pbp2a, and pbp2b genes individually from a genetically well-characterized serotype V GBS strain and studied the phenotypes of the four isogenic mutant strains. Compared to the wild-type parental strain, (i) none of the pbp isogenic mutant strains had a significant growth defect in Todd-Hewitt broth supplemented with 0.2% yeast extract (THY) rich medium, (ii) isogenic mutant Δpbp1a and Δpbp1b strains had significantly increased susceptibility to penicillin and ampicillin, and (iii) isogenic mutant Δpbp1a and Δpbp2b strains had significantly longer chain lengths. Using saturated transposon mutagenesis and transposon insertion site sequencing, we determined the genes essential for the viability of the wild-type GBS strain and each of the four isogenic pbp deletion mutant strains in THY rich medium. The pbp1a gene is essential for cell viability in the pbp2b deletion background. Reciprocally, pbp2b is essential in the pbp1a deletion background. Moreover, the gene encoding RodA, a peptidoglycan polymerase that works in conjunction with PBP2B, is also essential in the pbp1a deletion background. Together, our results suggest functional overlap between PBP1A and the PBP2B-RodA complex in GBS cell wall peptidoglycan biosynthesis. IMPORTANCE High-molecular-mass penicillin-binding proteins (HMM PBPs) are enzymes required for bacterial cell wall biosynthesis. Bacterial pathogen group B streptococcus (GBS) produces five distinct HMM PBPs. The biological functions of these proteins are not well characterized in GBS. In this study, we performed a comprehensive deletion analysis of genes encoding HMM PBPs in GBS. We found that deleting certain PBP-encoding genes altered bacterial susceptibility to beta-lactam antibiotics, cell morphology, and the essentiality of other enzymes involved in cell wall peptidoglycan synthesis. The results of our study shed new light on the biological functions of PBPs in GBS.
Collapse
|
12
|
(p)ppGpp/GTP and Malonyl-CoA Modulate Staphylococcus aureus Adaptation to FASII Antibiotics and Provide a Basis for Synergistic Bi-Therapy. mBio 2021; 12:mBio.03193-20. [PMID: 33531402 PMCID: PMC7858065 DOI: 10.1128/mbio.03193-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a major human bacterial pathogen for which new inhibitors are urgently needed. Antibiotic development has centered on the fatty acid synthesis (FASII) pathway, which provides the building blocks for bacterial membrane phospholipids. Fatty acid biosynthesis (FASII) enzymes are considered valid targets for antimicrobial drug development against the human pathogen Staphylococcus aureus. However, incorporation of host fatty acids confers FASII antibiotic adaptation that compromises prospective treatments. S. aureus adapts to FASII inhibitors by first entering a nonreplicative latency period, followed by outgrowth. Here, we used transcriptional fusions and direct metabolite measurements to investigate the factors that dictate the duration of latency prior to outgrowth. We show that stringent response induction leads to repression of FASII and phospholipid synthesis genes. (p)ppGpp induction inhibits synthesis of malonyl-CoA, a molecule that derepresses FapR, a key regulator of FASII and phospholipid synthesis. Anti-FASII treatment also triggers transient expression of (p)ppGpp-regulated genes during the anti-FASII latency phase, with concomitant repression of FapR regulon expression. These effects are reversed upon outgrowth. GTP depletion, a known consequence of the stringent response, also occurs during FASII latency, and is proposed as the common signal linking these responses. We next showed that anti-FASII treatment shifts malonyl-CoA distribution between its interactants FapR and FabD, toward FapR, increasing expression of the phospholipid synthesis genes plsX and plsC during outgrowth. We conclude that components of the stringent response dictate malonyl-CoA availability in S. aureus FASII regulation, and contribute to latency prior to anti-FASII-adapted outgrowth. A combinatory approach, coupling a (p)ppGpp inducer and an anti-FASII, blocks S. aureus outgrowth, opening perspectives for bi-therapy treatment.
Collapse
|
13
|
Seepersaud R, Anderson AC, Bensing BA, Choudhury BP, Clarke AJ, Sullam PM. O-acetylation controls the glycosylation of bacterial serine-rich repeat glycoproteins. J Biol Chem 2021; 296:100249. [PMID: 33384382 PMCID: PMC7948813 DOI: 10.1074/jbc.ra120.016116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Revised: 12/21/2020] [Accepted: 12/31/2020] [Indexed: 01/14/2023] Open
Abstract
The serine-rich repeat (SRR) glycoproteins of gram-positive bacteria are a family of adhesins that bind to a wide range of host ligands, and expression of SRR glycoproteins is linked with enhanced bacterial virulence. The biogenesis of these surface glycoproteins involves their intracellular glycosylation and export via the accessory Sec system. Although all accessory Sec components are required for SRR glycoprotein export, Asp2 of Streptococcus gordonii also functions as an O-acetyltransferase that modifies GlcNAc residues on the SRR adhesin gordonii surface protein B (GspB). Because these GlcNAc residues can also be modified by the glycosyltransferases Nss and Gly, it has been unclear whether the post-translational modification of GspB is coordinated. We now report that acetylation modulates the glycosylation of exported GspB. Loss of O-acetylation due to aps2 mutagenesis led to the export of GspB glycoforms with increased glucosylation of the GlcNAc moieties. Linkage analysis of the GspB glycan revealed that both O-acetylation and glucosylation occurred at the same C6 position on GlcNAc residues and that O-acetylation prevented Glc deposition. Whereas streptococci expressing nonacetylated GspB with increased glucosylation were significantly reduced in their ability to bind human platelets in vitro, deletion of the glycosyltransferases nss and gly in the asp2 mutant restored platelet binding to WT levels. These findings demonstrate that GlcNAc O-acetylation controls GspB glycosylation, such that binding via this adhesin is optimized. Moreover, because O-acetylation has comparable effects on the glycosylation of other SRR adhesins, acetylation may represent a conserved regulatory mechanism for the post-translational modification of the SRR glycoprotein family.
Collapse
Affiliation(s)
- Ravin Seepersaud
- Department of Medicine, Division of Infectious Diseases, San Francisco Veteran Affairs Medical Center, and the Department of Medicine, University of California, San Francisco, California, USA
| | - Alexander C Anderson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Barbara A Bensing
- Department of Medicine, Division of Infectious Diseases, San Francisco Veteran Affairs Medical Center, and the Department of Medicine, University of California, San Francisco, California, USA
| | - Biswa P Choudhury
- GlycoAnalytics Core, University of California, San Diego, San Diego, California, USA
| | - Anthony J Clarke
- Department of Chemistry and Biochemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Paul M Sullam
- Department of Medicine, Division of Infectious Diseases, San Francisco Veteran Affairs Medical Center, and the Department of Medicine, University of California, San Francisco, California, USA.
| |
Collapse
|
14
|
Chan JM, Gori A, Nobbs AH, Heyderman RS. Streptococcal Serine-Rich Repeat Proteins in Colonization and Disease. Front Microbiol 2020; 11:593356. [PMID: 33193266 PMCID: PMC7661464 DOI: 10.3389/fmicb.2020.593356] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 10/12/2020] [Indexed: 01/10/2023] Open
Abstract
Glycosylation of proteins, previously thought to be absent in prokaryotes, is increasingly recognized as important for both bacterial colonization and pathogenesis. For mucosal pathobionts, glycoproteins that function as cell wall-associated adhesins facilitate interactions with mucosal surfaces, permitting persistent adherence, invasion of deeper tissues and transition to disease. This is exemplified by Streptococcus pneumoniae and Streptococcus agalactiae, which can switch from being relatively harmless members of the mucosal tract microbiota to bona fide pathogens that cause life-threatening diseases. As part of their armamentarium of virulence factors, streptococci encode a family of large, glycosylated serine-rich repeat proteins (SRRPs) that facilitate binding to various tissue types and extracellular matrix proteins. This minireview focuses on the roles of S. pneumoniae and S. agalactiae SRRPs in persistent colonization and the transition to disease. The potential of utilizing SRRPs as vaccine targets will also be discussed.
Collapse
Affiliation(s)
- Jia Mun Chan
- NIHR Mucosal Pathogens Research Unit, Division of Infection and Immunity, University College London, London, United Kingdom
| | - Andrea Gori
- NIHR Mucosal Pathogens Research Unit, Division of Infection and Immunity, University College London, London, United Kingdom
| | - Angela H. Nobbs
- Bristol Dental School, University of Bristol, Bristol, United Kingdom
| | - Robert S. Heyderman
- NIHR Mucosal Pathogens Research Unit, Division of Infection and Immunity, University College London, London, United Kingdom
| |
Collapse
|
15
|
Stubbs HE, Bensing BA, Yamakawa I, Sharma P, Yu H, Chen X, Sullam PM, Iverson TM. Tandem sialoglycan-binding modules in a Streptococcus sanguinis serine-rich repeat adhesin create target dependent avidity effects. J Biol Chem 2020; 295:14737-14749. [PMID: 32820052 PMCID: PMC7586212 DOI: 10.1074/jbc.ra120.014177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/29/2020] [Indexed: 01/07/2023] Open
Abstract
Sialic acid-binding immunoglobulin-like lectins (Siglec)-like domains of streptococcal serine-rich repeat (SRR) adhesins recognize sialylated glycans on human salivary, platelet, and plasma glycoproteins via a YTRY sequence motif. The SRR adhesin from Streptococcus sanguinis strain SK1 has tandem sialoglycan-binding domains and has previously been shown to bind sialoglycans with high affinity. However, both domains contain substitutions within the canonical YTRY motif, making it unclear how they interact with host receptors. To identify how the S. sanguinis strain SK1 SRR adhesin affects interactions with sialylated glycans and glycoproteins, we determined high-resolution crystal structures of the binding domains alone and with purified trisaccharides. These structural studies determined that the ligands still bind at the noncanonical binding motif, but with fewer hydrogen-bonding interactions to the protein than is observed in structures of other Siglec-like adhesins. Complementary biochemical studies identified that each of the two binding domains has a different selectivity profile. Interestingly, the binding of SK1 to platelets and plasma glycoproteins identified that the interaction to some host targets is dominated by the contribution of one binding domain, whereas the binding to other host receptors is mediated by both binding domains. These results provide insight into outstanding questions concerning the roles of tandem domains in targeting host receptors and suggest mechanisms for how pathogens can adapt to the availability of a range of related but nonidentical host receptors. They further suggest that the definition of the YTRY motif should be changed to ϕTRX, a more rigorous description of this sialic acid-recognition motif given recent findings.
Collapse
Affiliation(s)
- Haley E. Stubbs
- Graduate Program in Chemical and Physical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Barbara A. Bensing
- Department of Medicine, Veterans Affairs Medical Center, San Francisco, California, USA,Department of Medicine, University of California, San Francisco, California, USA
| | - Izumi Yamakawa
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
| | - Pankaj Sharma
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
| | - Hai Yu
- Department of Chemistry, University of California, Davis, California, USA
| | - Xi Chen
- Department of Chemistry, University of California, Davis, California, USA
| | - Paul M. Sullam
- Department of Medicine, Veterans Affairs Medical Center, San Francisco, California, USA
| | - T. M. Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA,Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA,Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA,For correspondence: T. M. Iverson,
| |
Collapse
|
16
|
Genome-Wide Assessment of Streptococcus agalactiae Genes Required for Survival in Human Whole Blood and Plasma. Infect Immun 2020; 88:IAI.00357-20. [PMID: 32747604 DOI: 10.1128/iai.00357-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 07/26/2020] [Indexed: 12/17/2022] Open
Abstract
Streptococcus agalactiae (group B streptococcus, or GBS) is a common cause of bacteremia and sepsis in newborns, pregnant women, and immunocompromised patients. The molecular mechanisms used by GBS to survive and proliferate in blood are not well understood. Here, using a highly virulent GBS strain and transposon-directed insertion site sequencing (TraDIS), we performed genome-wide screens to discover novel GBS genes required for bacterial survival in human whole blood and plasma. The screen identified 85 and 41 genes that are required for GBS growth in whole blood and plasma, respectively. A common set of 29 genes was required in both whole blood and plasma. Targeted gene deletion confirmed that (i) genes encoding methionine transporter (metP) and manganese transporter (mtsA) are crucial for GBS survival in whole blood and plasma, (ii) gene W903_1820, encoding a small multidrug export family protein, contributes significantly to GBS survival in whole blood, (iii) the shikimate pathway gene aroA is essential for GBS growth in whole blood and plasma, and (iv) deletion of srr1, encoding a fibrinogen-binding adhesin, increases GBS survival in whole blood. Our findings provide new insight into the GBS-host interactions in human blood.
Collapse
|
17
|
Choudhary P, Badmalia MD, Rao A. Shape-function insights into bifunctional O-GlcNActransferase of Listeria monocytogenes EGD-e. Glycobiology 2020; 31:275-287. [PMID: 32776104 DOI: 10.1093/glycob/cwaa076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 08/04/2020] [Accepted: 08/04/2020] [Indexed: 12/13/2022] Open
Abstract
O-GlcNAcylation is an important post-translational modification of proteins. O-GlcNAcylated proteins have crucial roles in several cellular contexts both in eukaryotes and bacteria. O-GlcNActransferase (OGT) is the enzyme instrumental in O-GlcNAcylation of proteins. OGT is conserved across eukaryotes. The first bacterial OGT discovered is GmaR in Listeria monocytogenes. GmaR is a GT-2 family bifunctional protein that catalyzes glycosylation of the flagellin protein FlaA and controls transcription of flagellar motility genes in a temperature-dependent manner. Here, we provide methods for heterologous expression and purification of recombinant GmaR and FlaA, in vivo/in vitro glycosylation assays, analysis of the molecular form of recombinant GmaR and detailed enzyme kinetics. We study the structure and functional dynamics of GmaR. Using solution small-angle X-ray scattering and molecular modeling, we show that GmaR adopts an extended shape with two distinctly spaced structural units in the presence of cofactor Mg2+ and with donor UDP-GlcNAc and cofactor combined. Comparisons of restored structures revealed that in-solution binding of Mg2+ ions brings about shape rearrangements and induces structural-rigidity in hyper-variable regions at the N-terminus of GmaR protein. Taking function and shape data together, we describe that Mg2+ binding enables GmaR to adopt a shape that can bind the substrate. The manuscript provides the first 3D solution structure of a bacterial OGT of GT-2 family and detailed biochemical characterization of GmaR to facilitate its future applications.
Collapse
Affiliation(s)
| | - Maulik D Badmalia
- CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India
| | | | - Alka Rao
- CSIR-Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India.,Academy of Scientific and Innovation Research (AcSIR), Sector 19, Kamla Nehru Nagar, Ghaziabad 201002, India
| |
Collapse
|
18
|
Abstract
In addition to SecA of the general Sec system, many Gram-positive bacteria, including mycobacteria, express SecA2, a second, transport-associated ATPase. SecA2s can be subdivided into two mechanistically distinct types: (i) SecA2s that are part of the accessory Sec (aSec) system, a specialized transporter mediating the export of a family of serine-rich repeat (SRR) glycoproteins that function as adhesins, and (ii) SecA2s that are part of multisubstrate systems, in which SecA2 interacts with components of the general Sec system, specifically the SecYEG channel, to export multiple types of substrates. Found mainly in streptococci and staphylococci, the aSec system also contains SecY2 and novel accessory Sec proteins (Asps) that are required for optimal export. Asp2 also acetylates glucosamine residues on the SRR domains of the substrate during transport. Targeting of the SRR substrate to SecA2 and the aSec translocon is mediated by a specialized signal peptide. Multisubstrate SecA2 systems are present in mycobacteria, corynebacteria, listeriae, clostridia, and some bacillus species. Although most substrates for this SecA2 have canonical signal peptides that are required for export, targeting to SecA2 appears to depend on structural features of the mature protein. The feature of the mature domains of these proteins that renders them dependent on SecA2 for export may be their potential to fold in the cytoplasm. The discovery of aSec and multisubstrate SecA2 systems expands our appreciation of the diversity of bacterial export pathways. Here we present our current understanding of the mechanisms of each of these SecA2 systems.
Collapse
|
19
|
Abstract
Extracellular polysaccharides and glycoproteins of pathogenic bacteria assist in adherence, autoaggregation, biofilm formation, and host immune system evasion. As a result, considerable research in the field of glycobiology is dedicated to study the composition and function of glycans associated with virulence, as well as the enzymes involved in their biosynthesis with the aim to identify novel antibiotic targets. Especially, insights into the enzyme mechanism, substrate binding, and transition-state structures are valuable as a starting point for rational inhibitor design. An intriguing aspect of enzymes that generate or process polysaccharides and glycoproteins is the level of processivity. The existence of enzymatic processivity reflects the need for regulation of the final glycan/glycoprotein length and structure, depending on the role they perform. In this Review, we describe the currently reported examples of various processive enzymes involved in polymerization and transfer of sugar moieties, predominantly in bacterial pathogens, with a focus on the biochemical methods, to showcase the importance of studying processivity for understanding the mechanism.
Collapse
Affiliation(s)
- Liubov Yakovlieva
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Marthe T. C. Walvoort
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| |
Collapse
|
20
|
Streptococcus oralis subsp. dentisani Produces Monolateral Serine-Rich Repeat Protein Fibrils, One of Which Contributes to Saliva Binding via Sialic Acid. Infect Immun 2019; 87:IAI.00406-19. [PMID: 31308084 DOI: 10.1128/iai.00406-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 07/08/2019] [Indexed: 12/27/2022] Open
Abstract
Our studies reveal that the oral colonizer and cause of infective endocarditis Streptococcus oralis subsp. dentisani displays a striking monolateral distribution of surface fibrils. Furthermore, our data suggest that these fibrils impact the structure of adherent bacterial chains. Mutagenesis studies indicate that these fibrils are dependent on three serine-rich repeat proteins (SRRPs), here named fibril-associated protein A (FapA), FapB, and FapC, and that each SRRP forms a different fibril with a distinct distribution. SRRPs are a family of bacterial adhesins that have diverse roles in adhesion and that can bind to different receptors through modular nonrepeat region domains. Amino acid sequence and predicted structural similarity searches using the nonrepeat regions suggested that FapA may contribute to interspecies interactions, that FapA and FapB may contribute to intraspecies interactions, and that FapC may contribute to sialic acid binding. We demonstrate that a fapC mutant was significantly reduced in binding to saliva. We confirmed a role for FapC in sialic acid binding by demonstrating that the parental strain was significantly reduced in adhesion upon addition of a recombinantly expressed, sialic acid-specific, carbohydrate binding module, while the fapC mutant was not reduced. However, mutation of a residue previously shown to be essential for sialic acid binding did not decrease bacterial adhesion, leaving the precise mechanism of FapC-mediated adhesion to sialic acid to be defined. We also demonstrate that the presence of any one of the SRRPs is sufficient for efficient biofilm formation. Similar structures were observed on all infective endocarditis isolates examined, suggesting that this distribution is a conserved feature of this S. oralis subspecies.
Collapse
|
21
|
Latousakis D, MacKenzie DA, Telatin A, Juge N. Serine-rich repeat proteins from gut microbes. Gut Microbes 2019; 11:102-117. [PMID: 31035824 PMCID: PMC6973325 DOI: 10.1080/19490976.2019.1602428] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 03/08/2019] [Accepted: 03/27/2019] [Indexed: 02/03/2023] Open
Abstract
Serine-rich repeat proteins (SRRPs) have emerged as an important group of cell surface adhesins found in a growing number of Gram-positive bacteria. Studies focused on SRRPs from streptococci and staphylococci demonstrated that these proteins are O-glycosylated on serine or threonine residues and exported via an accessory secretion (aSec) system. In pathogens, these adhesins contribute to disease pathogenesis and represent therapeutic targets. Recently, the non-canonical aSec system has been identified in the genomes of gut microbes and characterization of their associated SRRPs is beginning to unfold, showing their role in mediating attachment and biofilm formation. Here we provide an update of the occurrence, structure, and function of SRRPs across bacteria, with emphasis on the molecular and biochemical properties of SRRPs from gut symbionts, particularly Lactobacilli. These emerging studies underscore the range of ligands recognized by these adhesins and the importance of SRRP glycosylation in the interaction of gut microbes with the host.
Collapse
Affiliation(s)
- Dimitrios Latousakis
- The Gut Microbes and Health Institute Strategic Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Donald A. MacKenzie
- The Gut Microbes and Health Institute Strategic Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Andrea Telatin
- The Gut Microbes and Health Institute Strategic Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| | - Nathalie Juge
- The Gut Microbes and Health Institute Strategic Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK
| |
Collapse
|
22
|
A comprehensive review of signal peptides: Structure, roles, and applications. Eur J Cell Biol 2018; 97:422-441. [DOI: 10.1016/j.ejcb.2018.06.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 06/18/2018] [Accepted: 06/18/2018] [Indexed: 01/06/2023] Open
|
23
|
Pietrocola G, Arciola CR, Rindi S, Montanaro L, Speziale P. Streptococcus agalactiae Non-Pilus, Cell Wall-Anchored Proteins: Involvement in Colonization and Pathogenesis and Potential as Vaccine Candidates. Front Immunol 2018; 9:602. [PMID: 29686667 PMCID: PMC5900788 DOI: 10.3389/fimmu.2018.00602] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 03/09/2018] [Indexed: 11/13/2022] Open
Abstract
Group B Streptococcus (GBS) remains an important etiological agent of several infectious diseases including neonatal septicemia, pneumonia, meningitis, and orthopedic device infections. This pathogenicity is due to a variety of virulence factors expressed by Streptococcus agalactiae. Single virulence factors are not sufficient to provoke a streptococcal infection, which is instead promoted by the coordinated activity of several pathogenicity factors. Such determinants, mostly cell wall-associated and secreted proteins, include adhesins that mediate binding of the pathogen to host extracellular matrix/plasma ligands and cell surfaces, proteins that cooperate in the invasion of and survival within host cells and factors that neutralize phagocytosis and/or modulate the immune response. The genome-based approaches and bioinformatics tools and the extensive use of biophysical and biochemical methods and animal model studies have provided a great wealth of information on the molecular structure and function of these virulence factors. In fact, a number of new GBS surface-exposed or secreted proteins have been identified (GBS immunogenic bacterial adhesion protein, leucine-rich repeat of GBS, serine-rich repeat proteins), the three-dimensional structures of known streptococcal proteins (αC protein, C5a peptidase) have been solved and an understanding of the pathogenetic role of "old" and new determinants has been better defined in recent years. Herein, we provide an update of our current understanding of the major surface cell wall-anchored proteins from GBS, with emphasis on their biochemical and structural properties and the pathogenetic roles they may have in the onset and progression of host infection. We also focus on the antigenic profile of these compounds and discuss them as targets for therapeutic intervention.
Collapse
Affiliation(s)
- Giampiero Pietrocola
- Unit of Biochemistry, Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Carla Renata Arciola
- Research Unit on Implant Infections, Rizzoli Orthopaedic Institute, Bologna, Italy.,Department of Experimental, Diagnostic, and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Simonetta Rindi
- Unit of Biochemistry, Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Lucio Montanaro
- Research Unit on Implant Infections, Rizzoli Orthopaedic Institute, Bologna, Italy.,Department of Experimental, Diagnostic, and Specialty Medicine, University of Bologna, Bologna, Italy
| | - Pietro Speziale
- Unit of Biochemistry, Department of Molecular Medicine, University of Pavia, Pavia, Italy.,Department of Industrial and Information Engineering, University of Pavia, Pavia, Italy
| |
Collapse
|
24
|
Avilés-Reyes A, Freires IA, Besingi R, Purushotham S, Deivanayagam C, Brady LJ, Abranches J, Lemos JA. Characterization of the pgf operon involved in the posttranslational modification of Streptococcus mutans surface proteins. Sci Rep 2018; 8:4705. [PMID: 29549320 PMCID: PMC5856776 DOI: 10.1038/s41598-018-23170-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 03/07/2018] [Indexed: 01/04/2023] Open
Abstract
Protein glycosylation has been described as the most abundant and complex post-translational modification occurring in nature. Recent studies have enhanced our view of how this modification occurs in bacteria highlighting the role of protein glycosylation in various processes such as biofilm formation, virulence and host-microbe interactions. We recently showed that the collagen- and laminin-binding adhesin Cnm of the dental pathogen Streptococcus mutans is post-translationally modified by the PgfS glycosyltransferase. Following this initial identification of Cnm as a glycoprotein, we have now identified additional genes (pgfM1, pgfE and pgfM2) that are also involved in the posttranslational modification of Cnm. Similar to the previously characterized ΔpgfS strain, inactivation of pgfM1, pgfE or pgfM2 directly impacts Cnm by altering its migration pattern, proteolytic stability and function. In addition, we identified the wall-associated protein A (WapA) as an additional substrate of Pgf-dependent modification. We conclude that the pgS-pgfM1-pgfE-pgfM2 operon encodes for a protein machinery that can modify, likely through the addition of glycans, both core and non-core gene products in S. mutans.
Collapse
Affiliation(s)
- Alejandro Avilés-Reyes
- Department of Oral Biology, University of Florida, College of Dentistry, Gainesville, FL, USA
| | - Irlan Almeida Freires
- Department of Oral Biology, University of Florida, College of Dentistry, Gainesville, FL, USA
| | - Richard Besingi
- Department of Oral Biology, University of Florida, College of Dentistry, Gainesville, FL, USA
| | - Sangeetha Purushotham
- Department of Biochemistry and Molecular Genetics, University of Alabama, Birmingham, AL, USA
| | - Champion Deivanayagam
- Department of Biochemistry and Molecular Genetics, University of Alabama, Birmingham, AL, USA
| | - L Jeannine Brady
- Department of Oral Biology, University of Florida, College of Dentistry, Gainesville, FL, USA
| | - Jacqueline Abranches
- Department of Oral Biology, University of Florida, College of Dentistry, Gainesville, FL, USA.
| | - José A Lemos
- Department of Oral Biology, University of Florida, College of Dentistry, Gainesville, FL, USA.
| |
Collapse
|
25
|
Latousakis D, Juge N. How Sweet Are Our Gut Beneficial Bacteria? A Focus on Protein Glycosylation in Lactobacillus. Int J Mol Sci 2018; 19:ijms19010136. [PMID: 29301365 PMCID: PMC5796085 DOI: 10.3390/ijms19010136] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 12/22/2017] [Accepted: 12/27/2017] [Indexed: 02/07/2023] Open
Abstract
Protein glycosylation is emerging as an important feature in bacteria. Protein glycosylation systems have been reported and studied in many pathogenic bacteria, revealing an important diversity of glycan structures and pathways within and between bacterial species. These systems play key roles in virulence and pathogenicity. More recently, a large number of bacterial proteins have been found to be glycosylated in gut commensal bacteria. We present an overview of bacterial protein glycosylation systems (O- and N-glycosylation) in bacteria, with a focus on glycoproteins from gut commensal bacteria, particularly Lactobacilli. These emerging studies underscore the importance of bacterial protein glycosylation in the interaction of the gut microbiota with the host.
Collapse
Affiliation(s)
- Dimitrios Latousakis
- Quadram Institute Bioscience, The Gut Health and Food Safety Institute Strategic Programme, Norwich Research Park, Norwich NR4 7UA, UK.
| | - Nathalie Juge
- Quadram Institute Bioscience, The Gut Health and Food Safety Institute Strategic Programme, Norwich Research Park, Norwich NR4 7UA, UK.
| |
Collapse
|
26
|
Lee JY, Han GG, Kim EB, Choi YJ. Comparative genomics of Lactobacillus salivarius strains focusing on their host adaptation. Microbiol Res 2017; 205:48-58. [DOI: 10.1016/j.micres.2017.08.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/25/2017] [Accepted: 08/12/2017] [Indexed: 01/15/2023]
|
27
|
Seepersaud R, Sychantha D, Bensing BA, Clarke AJ, Sullam PM. O-acetylation of the serine-rich repeat glycoprotein GspB is coordinated with accessory Sec transport. PLoS Pathog 2017; 13:e1006558. [PMID: 28827841 PMCID: PMC5578698 DOI: 10.1371/journal.ppat.1006558] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 08/31/2017] [Accepted: 07/28/2017] [Indexed: 11/17/2022] Open
Abstract
The serine-rich repeat (SRR) glycoproteins are a family of adhesins found in many Gram-positive bacteria. Expression of the SRR adhesins has been linked to virulence for a variety of infections, including streptococcal endocarditis. The SRR preproteins undergo intracellular glycosylation, followed by export via the accessory Sec (aSec) system. This specialized transporter is comprised of SecA2, SecY2 and three to five accessory Sec proteins (Asps) that are required for export. Although the post-translational modification and transport of the SRR adhesins have been viewed as distinct processes, we found that Asp2 of Streptococcus gordonii also has an important role in modifying the SRR adhesin GspB. Biochemical analysis and mass spectrometry indicate that Asp2 is an acetyltransferase that modifies N-acetylglucosamine (GlcNAc) moieties on the SRR domains of GspB. Targeted mutations of the predicted Asp2 catalytic domain had no effect on transport, but abolished acetylation. Acetylated forms of GspB were only detected when the protein was exported via the aSec system, but not when transport was abolished by secA2 deletion. In addition, GspB variants rerouted to export via the canonical Sec pathway also lacked O-acetylation, demonstrating that this modification is specific to export via the aSec system. Streptococci expressing GspB lacking O-acetylated GlcNAc were significantly reduced in their ability bind to human platelets in vitro, an interaction that has been strongly linked to virulence in the setting of endocarditis. These results demonstrate that Asp2 is a bifunctional protein involved in both the post-translational modification and transport of SRR glycoproteins. In addition, these findings indicate that these processes are coordinated during the biogenesis of SRR glycoproteins, such that the adhesin is optimally modified for binding. This requirement for the coupling of modification and export may explain the co-evolution of the SRR glycoproteins with their specialized glycan modifying and export systems.
Collapse
Affiliation(s)
- Ravin Seepersaud
- San Francisco Veteran Affairs Medical Center, and the University of California, San Francisco, San Francisco, CA, United States of America
| | - David Sychantha
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Barbara A Bensing
- San Francisco Veteran Affairs Medical Center, and the University of California, San Francisco, San Francisco, CA, United States of America
| | - Anthony J Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Paul M Sullam
- San Francisco Veteran Affairs Medical Center, and the University of California, San Francisco, San Francisco, CA, United States of America
| |
Collapse
|
28
|
Couvigny B, Lapaque N, Rigottier-Gois L, Guillot A, Chat S, Meylheuc T, Kulakauskas S, Rohde M, Mistou MY, Renault P, Doré J, Briandet R, Serror P, Guédon E. Three glycosylated serine-rich repeat proteins play a pivotal role in adhesion and colonization of the pioneer commensal bacterium,Streptococcus salivarius. Environ Microbiol 2017; 19:3579-3594. [DOI: 10.1111/1462-2920.13853] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 06/29/2017] [Accepted: 06/30/2017] [Indexed: 01/25/2023]
Affiliation(s)
- Benoit Couvigny
- MICALIS Institute, INRA, AgroParisTech; Université Paris-Saclay; Jouy-en-Josas France
| | - Nicolas Lapaque
- MICALIS Institute, INRA, AgroParisTech; Université Paris-Saclay; Jouy-en-Josas France
| | - Lionel Rigottier-Gois
- MICALIS Institute, INRA, AgroParisTech; Université Paris-Saclay; Jouy-en-Josas France
| | - Alain Guillot
- MICALIS Institute, INRA, AgroParisTech; Université Paris-Saclay; Jouy-en-Josas France
| | - Sophie Chat
- INRA, Plateforme MIMA2; Jouy-en-josas France
| | - Thierry Meylheuc
- MICALIS Institute, INRA, AgroParisTech; Université Paris-Saclay; Jouy-en-Josas France
- INRA, Plateforme MIMA2; Jouy-en-josas France
| | - Saulius Kulakauskas
- MICALIS Institute, INRA, AgroParisTech; Université Paris-Saclay; Jouy-en-Josas France
| | - Manfred Rohde
- HZI, Helmholtz Centre for Infection Research; Braunschweig Germany
| | - Michel-Yves Mistou
- Laboratory for Food Safety; Université Paris-Est, ANSES; Maisons-Alfort France
| | - Pierre Renault
- MICALIS Institute, INRA, AgroParisTech; Université Paris-Saclay; Jouy-en-Josas France
| | - Joel Doré
- MICALIS Institute, INRA, AgroParisTech; Université Paris-Saclay; Jouy-en-Josas France
| | - Romain Briandet
- MICALIS Institute, INRA, AgroParisTech; Université Paris-Saclay; Jouy-en-Josas France
| | - Pascale Serror
- MICALIS Institute, INRA, AgroParisTech; Université Paris-Saclay; Jouy-en-Josas France
| | - Eric Guédon
- STLO, UMR1253, INRA, Agrocampus Ouest; Rennes France
| |
Collapse
|
29
|
Vornhagen J, Adams Waldorf KM, Rajagopal L. Perinatal Group B Streptococcal Infections: Virulence Factors, Immunity, and Prevention Strategies. Trends Microbiol 2017. [PMID: 28633864 DOI: 10.1016/j.tim.2017.05.013] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Group B streptococcus (GBS) or Streptococcus agalactiae is a β-hemolytic, Gram-positive bacterium that is a leading cause of neonatal infections. GBS commonly colonizes the lower gastrointestinal and genital tracts and, during pregnancy, neonates are at risk of infection. Although intrapartum antibiotic prophylaxis during labor and delivery has decreased the incidence of early-onset neonatal infection, these measures do not prevent ascending infection that can occur earlier in pregnancy leading to preterm births, stillbirths, or late-onset neonatal infections. Prevention of GBS infection in pregnancy is complex and is likely influenced by multiple factors, including pathogenicity, host factors, vaginal microbiome, false-negative screening, and/or changes in antibiotic resistance. A deeper understanding of the mechanisms of GBS infections during pregnancy will facilitate the development of novel therapeutics and vaccines. Here, we summarize and discuss important advancements in our understanding of GBS vaginal colonization, ascending infection, and preterm birth.
Collapse
Affiliation(s)
- Jay Vornhagen
- Department of Global Health, University of Washington, Seattle, WA, USA; Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Kristina M Adams Waldorf
- Department of Obstetrics and Gynecology, University of Washington, Seattle, WA, USA; Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden
| | - Lakshmi Rajagopal
- Department of Global Health, University of Washington, Seattle, WA, USA; Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Pediatrics, University of Washington, Seattle, WA, USA.
| |
Collapse
|
30
|
Streptococcus oralis Neuraminidase Modulates Adherence to Multiple Carbohydrates on Platelets. Infect Immun 2017; 85:IAI.00774-16. [PMID: 27993975 DOI: 10.1128/iai.00774-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 12/15/2016] [Indexed: 11/20/2022] Open
Abstract
Adherence to host surfaces is often mediated by bacterial binding to surface carbohydrates. Although it is widely appreciated that some bacterial species express glycosidases, previous studies have not considered whether bacteria bind to multiple carbohydrates within host glycans as they are modified by bacterial glycosidases. Streptococcus oralis is a leading cause of subacute infective endocarditis. Binding to platelets is a critical step in disease; however, the mechanisms utilized by S. oralis remain largely undefined. Studies revealed that S. oralis, like Streptococcus gordonii and Streptococcus sanguinis, binds platelets via terminal sialic acid. However, unlike those organisms, S. oralis produces a neuraminidase, NanA, which cleaves terminal sialic acid. Further studies revealed that following NanA-dependent removal of terminal sialic acid, S. oralis bound exposed β-1,4-linked galactose. Adherence to both these carbohydrates required Fap1, the S. oralis member of the serine-rich repeat protein (SRRP) family of adhesins. Mutation of a conserved residue required for sialic acid binding by other SRRPs significantly reduced platelet binding, supporting the hypothesis that Fap1 binds this carbohydrate. The mechanism by which Fap1 contributes to β-1,4-linked galactose binding remains to be defined; however, binding may occur via additional domains of unknown function within the nonrepeat region, one of which shares some similarity with a carbohydrate binding module. This study is the first demonstration that an SRRP is required to bind β-1,4-linked galactose and the first time that one of these adhesins has been shown to be required for binding of multiple glycan receptors.
Collapse
|
31
|
Bleiziffer I, Eikmeier J, Pohlentz G, McAulay K, Xia G, Hussain M, Peschel A, Foster S, Peters G, Heilmann C. The Plasmin-Sensitive Protein Pls in Methicillin-Resistant Staphylococcus aureus (MRSA) Is a Glycoprotein. PLoS Pathog 2017; 13:e1006110. [PMID: 28081265 PMCID: PMC5230774 DOI: 10.1371/journal.ppat.1006110] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 12/02/2016] [Indexed: 01/16/2023] Open
Abstract
Most bacterial glycoproteins identified to date are virulence factors of pathogenic bacteria, i.e. adhesins and invasins. However, the impact of protein glycosylation on the major human pathogen Staphylococcus aureus remains incompletely understood. To study protein glycosylation in staphylococci, we analyzed lysostaphin lysates of methicillin-resistant Staphylococcus aureus (MRSA) strains by SDS-PAGE and subsequent periodic acid-Schiff’s staining. We detected four (>300, ∼250, ∼165, and ∼120 kDa) and two (>300 and ∼175 kDa) glycosylated surface proteins with strain COL and strain 1061, respectively. The ∼250, ∼165, and ∼175 kDa proteins were identified as plasmin-sensitive protein (Pls) by mass spectrometry. Previously, Pls has been demonstrated to be a virulence factor in a mouse septic arthritis model. The pls gene is encoded by the staphylococcal cassette chromosome (SCC)mec type I in MRSA that also encodes the methicillin resistance-conferring mecA and further genes. In a search for glycosyltransferases, we identified two open reading frames encoded downstream of pls on the SCCmec element, which we termed gtfC and gtfD. Expression and deletion analysis revealed that both gtfC and gtfD mediate glycosylation of Pls. Additionally, the recently reported glycosyltransferases SdgA and SdgB are involved in Pls glycosylation. Glycosylation occurs at serine residues in the Pls SD-repeat region and modifying carbohydrates are N-acetylhexosaminyl residues. Functional characterization revealed that Pls can confer increased biofilm formation, which seems to involve two distinct mechanisms. The first mechanism depends on glycosylation of the SD-repeat region by GtfC/GtfD and probably also involves eDNA, while the second seems to be independent of glycosylation as well as eDNA and may involve the centrally located G5 domains. Other previously known Pls properties are not related to the sugar modifications. In conclusion, Pls is a glycoprotein and Pls glycosyl residues can stimulate biofilm formation. Thus, sugar modifications may represent promising new targets for novel therapeutic or prophylactic measures against life-threatening S. aureus infections. Staphylococcus aureus is a serious pathogen that causes life-threatening infections due to its ability to attach to surfaces, form biofilms, and persist inside the host. One of previously identified virulence factors in S. aureus pathogenesis is the plasmin-sensitive surface protein Pls. We here identified Pls as a posttranslationally modified glycoprotein and characterized the domain within Pls that becomes glycosylated as well as the modifying sugars. Moreover, we found that the glycosyltransferases GtfC and GtfD carry out the glycosylation reactions. In a search for a role for the modifying sugars, we found that Pls can stimulate biofilm formation apparently via two distinct mechanisms, one being dependent on glycosylation by GtfC and GtfD the other being independent of glycosylation as well as eDNA. Moreover, we found that none of the already known Pls functions is mediated by the sugar moieties. Thus, we conclude that GtfC/GtfD-glycosylated Pls may contribute to MRSA pathogenicity via stimulation of biofilm formation and may serve as future target to combat or prevent infections with this serious pathogen.
Collapse
Affiliation(s)
- Isabelle Bleiziffer
- Institute of Medical Microbiology, University of Münster, Münster, Germany
- Interdisciplinary Center for Clinical Research (IZKF), University of Münster, Münster, Germany
| | - Julian Eikmeier
- Institute of Medical Microbiology, University of Münster, Münster, Germany
- Interdisciplinary Center for Clinical Research (IZKF), University of Münster, Münster, Germany
| | | | - Kathryn McAulay
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Guoqing Xia
- Division of Infection, Immunity and Respiratory Medicine, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Muzaffar Hussain
- Institute of Medical Microbiology, University of Münster, Münster, Germany
| | - Andreas Peschel
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), partner site Tübingen, University of Tübingen, Tübingen, Germany
| | - Simon Foster
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Georg Peters
- Institute of Medical Microbiology, University of Münster, Münster, Germany
- Interdisciplinary Center for Clinical Research (IZKF), University of Münster, Münster, Germany
- Cluster of Excellence EXC 1003, Cells in Motion, University of Münster, Münster, Germany
| | - Christine Heilmann
- Institute of Medical Microbiology, University of Münster, Münster, Germany
- Interdisciplinary Center for Clinical Research (IZKF), University of Münster, Münster, Germany
- * E-mail:
| |
Collapse
|
32
|
Abstract
Bacterial pathogens utilize a multitude of methods to invade mammalian hosts, damage tissue sites, and thwart the immune system from responding. One essential component of these strategies for many bacterial pathogens is the secretion of proteins across phospholipid membranes. Secreted proteins can play many roles in promoting bacterial virulence, from enhancing attachment to eukaryotic cells, to scavenging resources in an environmental niche, to directly intoxicating target cells and disrupting their functions. Many pathogens use dedicated protein secretion systems to secrete virulence factors from the cytosol of the bacteria into host cells or the host environment. In general, bacterial protein secretion apparatuses can be divided into classes, based on their structures, functions, and specificity. Some systems are conserved in all classes of bacteria and secrete a broad array of substrates, while others are only found in a small number of bacterial species and/or are specific to only one or a few proteins. In this chapter, we review the canonical features of several common bacterial protein secretion systems, as well as their roles in promoting the virulence of bacterial pathogens. Additionally, we address recent findings that indicate that the innate immune system of the host can detect and respond to the presence of protein secretion systems during mammalian infection.
Collapse
|
33
|
Almeida A, Alves-Barroco C, Sauvage E, Bexiga R, Albuquerque P, Tavares F, Santos-Sanches I, Glaser P. Persistence of a dominant bovine lineage of group B Streptococcus reveals genomic signatures of host adaptation. Environ Microbiol 2016; 18:4216-4229. [PMID: 27696631 DOI: 10.1111/1462-2920.13550] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 09/20/2016] [Accepted: 09/26/2016] [Indexed: 11/28/2022]
Abstract
Group B Streptococcus (GBS) is a host-generalist species, most notably causing disease in humans and cattle. However, the differential adaptation of GBS to its two main hosts, and the risk of animal to human infection remain poorly understood. Despite improvements in control measures across Europe, GBS is still one of the main causative agents of bovine mastitis in Portugal. Here, by whole-genome analysis of 150 bovine GBS isolates we discovered that a single CC61 clone is spreading throughout Portuguese herds since at least the early 1990s, having virtually replaced the previous GBS population. Mutations within an iron/manganese transporter were independently acquired by all of the CC61 isolates, underlining a key adaptive strategy to persist in the bovine host. Lateral transfer of bacteriocin production and antibiotic resistance genes also underscored the contribution of the microbial ecology and genetic pool within the bovine udder environment to the success of this clone. Compared to strains of human origin, GBS evolves twice as fast in bovines and undergoes recurrent pseudogenizations of human-adapted traits. Our work provides new insights into the potentially irreversible adaptation of GBS to the bovine environment.
Collapse
Affiliation(s)
- Alexandre Almeida
- Institut Pasteur, Unité Evolution et Ecologie de la Résistance aux Antibiotiques, Paris, France.,CNRS UMR 3525, Paris, France.,Université Pierre et Marie Curie, Paris, France
| | - Cinthia Alves-Barroco
- Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, UCIBIO - Unidade de Ciências Biomoleculares Aplicadas, Universidade NOVA de Lisboa, Lisboa, Portugal
| | - Elisabeth Sauvage
- Institut Pasteur, Unité Evolution et Ecologie de la Résistance aux Antibiotiques, Paris, France.,CNRS UMR 3525, Paris, France
| | - Ricardo Bexiga
- Faculdade de Medicina Veterinária, Centro de Investigação Interdisciplinar em Sanidade Animal, Universidade de Lisboa, Lisboa, Portugal
| | - Pedro Albuquerque
- CIBIO - Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Campus Agrário de Vairão, Vairão, Portugal
| | - Fernando Tavares
- CIBIO - Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Laboratório Associado, Universidade do Porto, Campus Agrário de Vairão, Vairão, Portugal.,Faculdade de Ciências, Departamento de Biologia, Universidade do Porto, Porto, Portugal
| | - Ilda Santos-Sanches
- Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, UCIBIO - Unidade de Ciências Biomoleculares Aplicadas, Universidade NOVA de Lisboa, Lisboa, Portugal
| | - Philippe Glaser
- Institut Pasteur, Unité Evolution et Ecologie de la Résistance aux Antibiotiques, Paris, France.,CNRS UMR 3525, Paris, France
| |
Collapse
|
34
|
Tytgat HLP, de Vos WM. Sugar Coating the Envelope: Glycoconjugates for Microbe-Host Crosstalk. Trends Microbiol 2016; 24:853-861. [PMID: 27374775 DOI: 10.1016/j.tim.2016.06.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/31/2016] [Accepted: 06/09/2016] [Indexed: 12/14/2022]
Abstract
Tremendous progress has been made on mapping the mainly bacterial members of the human intestinal microbiota. Knowledge on what is out there, or rather what is inside, needs to be complemented with insight on how these bacteria interact with their biotic environment. Bacterial glycoconjugates, that is, the collection of all glycan-modified molecules, are ideal modulators of such interactions. Their enormous versatility and diversity results in a species-specific glycan barcode, providing a range of ligands for host interaction. Recent reports on the functional importance of glycosylation of important bacterial ligands in beneficial and pathogenic species underpin this. Glycoconjugates, and glycoproteins in particular, are an underappreciated, potentially crucial, factor in understanding bacteria-host interactions of old friends and foes.
Collapse
Affiliation(s)
- Hanne L P Tytgat
- Laboratory of Microbiology, Wageningen University, 6708 WE Wageningen, The Netherlands; Institute of Microbiology, Swiss Federal Institute of Technology, ETH Zurich, 8093 Zurich, Switzerland
| | - Willem M de Vos
- Laboratory of Microbiology, Wageningen University, 6708 WE Wageningen, The Netherlands; Faculty of Medicine, Immunobiology Research Program, Department of Bacteriology and Immunology, University of Helsinki, 00290 Helsinki, Finland.
| |
Collapse
|
35
|
Buscetta M, Firon A, Pietrocola G, Biondo C, Mancuso G, Midiri A, Romeo L, Galbo R, Venza M, Venza I, Kaminski PA, Gominet M, Teti G, Speziale P, Trieu-Cuot P, Beninati C. PbsP, a cell wall-anchored protein that binds plasminogen to promote hematogenous dissemination of group B Streptococcus. Mol Microbiol 2016; 101:27-41. [PMID: 26888569 DOI: 10.1111/mmi.13357] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/15/2016] [Indexed: 02/04/2023]
Abstract
Streptococcus agalactiae (Group B Streptococcus or GBS) is a leading cause of invasive infections in neonates whose virulence is dependent on its ability to interact with cells and host components. We here characterized a surface protein with a critical function in GBS pathophysiology. This adhesin, designated PbsP, possesses two Streptococcal Surface Repeat domains, a methionine and lysine-rich region, and a LPXTG cell wall-anchoring motif. PbsP mediates plasminogen (Plg) binding both in vitro and in vivo and we showed that cell surface-bound Plg can be activated into plasmin by tissue plasminogen activator to increase the bacterial extracellular proteolytic activity. Absence of PbsP results in a decreased bacterial transmigration across brain endothelial cells and impaired virulence in a murine model of infection. PbsP is conserved among the main GBS lineages and is a major plasminogen adhesin in non-CC17 GBS strains. Importantly, immunization of mice with recombinant PbsP confers protective immunity. Our results indicate that GBS have evolved different strategies to recruit Plg which indicates that the ability to acquire cell surface proteolytic activity is essential for the invasiveness of this bacterium.
Collapse
Affiliation(s)
- Marco Buscetta
- Metchnikoff Laboratory, Departments of Human Pathology and Medicine, University of Messina, Messina, Italy.,Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram Positif, CNRS ERL3526, 75015, Paris, France
| | - Arnaud Firon
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram Positif, CNRS ERL3526, 75015, Paris, France
| | - Giampiero Pietrocola
- Department of Molecular Medicine, Unit of Biochemistry, University of Pavia, Pavia, Italy
| | - Carmelo Biondo
- Metchnikoff Laboratory, Departments of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Giuseppe Mancuso
- Metchnikoff Laboratory, Departments of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Angelina Midiri
- Metchnikoff Laboratory, Departments of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Letizia Romeo
- Metchnikoff Laboratory, Departments of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Roberta Galbo
- Metchnikoff Laboratory, Departments of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Mario Venza
- Metchnikoff Laboratory, Departments of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Isabella Venza
- Metchnikoff Laboratory, Departments of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Pierre-Alexandre Kaminski
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram Positif, CNRS ERL3526, 75015, Paris, France
| | - Myriam Gominet
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram Positif, CNRS ERL3526, 75015, Paris, France
| | - Giuseppe Teti
- Metchnikoff Laboratory, Departments of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Pietro Speziale
- Department of Molecular Medicine, Unit of Biochemistry, University of Pavia, Pavia, Italy
| | - Patrick Trieu-Cuot
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram Positif, CNRS ERL3526, 75015, Paris, France
| | - Concetta Beninati
- Metchnikoff Laboratory, Departments of Human Pathology and Medicine, University of Messina, Messina, Italy.,Scylla Biotech Srl, Messina, Italy
| |
Collapse
|
36
|
Morello E, Mallet A, Konto-Ghiorghi Y, Chaze T, Mistou MY, Oliva G, Oliveira L, Di Guilmi AM, Trieu-Cuot P, Dramsi S. Evidence for the Sialylation of PilA, the PI-2a Pilus-Associated Adhesin of Streptococcus agalactiae Strain NEM316. PLoS One 2015; 10:e0138103. [PMID: 26407005 PMCID: PMC4583379 DOI: 10.1371/journal.pone.0138103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/25/2015] [Indexed: 01/20/2023] Open
Abstract
Streptococcus agalactiae (or Group B Streptococcus, GBS) is a commensal bacterium present in the intestinal and urinary tracts of approximately 30% of humans. We and others previously showed that the PI-2a pilus polymers, made of the backbone pilin PilB, the tip adhesin PilA and the cell wall anchor protein PilC, promote adhesion to host epithelia and biofilm formation. Affinity-purified PI-2a pili from GBS strain NEM316 were recognized by N-acetylneuraminic acid (NeuNAc, also known as sialic acid) specific lectins such as Elderberry Bark Lectin (EBL) suggesting that pili are sialylated. Glycan profiling with twenty different lectins combined with monosaccharide composition by HPLC suggested that affinity-purified PI-2a pili are modified by N-glycosylation and decorated with sialic acid attached to terminal galactose. Analysis of various relevant mutants in the PI-2a pilus operon by flow-cytometry and electron microscopy analyses pointed to PilA as the pilus subunit modified by glycosylation. Double labeling using PilB antibody and EBL lectin, which specifically recognizes N-acetylneuraminic acid attached to galactose in α-2, 6, revealed a characteristic binding of EBL at the tip of the pilus structures, highly reminiscent of PilA localization. Expression of a secreted form of PilA using an inducible promoter showed that this recombinant PilA binds specifically to EBL lectin when produced in the native GBS context. In silico search for potentially glycosylated asparagine residues in PilA sequence pointed to N427 and N597, which appear conserved and exposed in the close homolog RrgA from S. pneumoniae, as likely candidates. Conversion of these two asparagyl residues to glutamyl resulted in a higher instability of PilA. Our results provide the first evidence that the tip PilA adhesin can be glycosylated, and suggest that this modification is critical for PilA stability and may potentially influence interactions with the host.
Collapse
Affiliation(s)
- Eric Morello
- Institut Pasteur, Unité des Bactéries Pathogènes à Gram positif, Paris, France
- Centre National de la Recherche Scientifique (CNRS ERL 3526), Paris, France
| | - Adeline Mallet
- Institut Pasteur, Imagopole, Ultrastructural Microscopy Platform, Paris, France
| | - Yoan Konto-Ghiorghi
- Institut Pasteur, Unité des Bactéries Pathogènes à Gram positif, Paris, France
- Centre National de la Recherche Scientifique (CNRS ERL 3526), Paris, France
| | - Thibault Chaze
- Institut Pasteur, Spectrométrie de Masse Structurale et Protéomique, Paris, France
- INRA UMR 1319, MICALIS, Jouy-en-Josas, France
| | | | - Giulia Oliva
- Institut Pasteur, Unité des Bactéries Pathogènes à Gram positif, Paris, France
- Centre National de la Recherche Scientifique (CNRS ERL 3526), Paris, France
| | - Liliana Oliveira
- Institut Pasteur, Unité des Bactéries Pathogènes à Gram positif, Paris, France
- Centre National de la Recherche Scientifique (CNRS ERL 3526), Paris, France
| | - Anne-Marie Di Guilmi
- Université Grenoble Alpes, Institut de Biologie Structurale (IBS), Grenoble, France
| | - Patrick Trieu-Cuot
- Institut Pasteur, Unité des Bactéries Pathogènes à Gram positif, Paris, France
- Centre National de la Recherche Scientifique (CNRS ERL 3526), Paris, France
| | - Shaynoor Dramsi
- Institut Pasteur, Unité des Bactéries Pathogènes à Gram positif, Paris, France
- Centre National de la Recherche Scientifique (CNRS ERL 3526), Paris, France
- * E-mail:
| |
Collapse
|
37
|
Six A, Bellais S, Bouaboud A, Fouet A, Gabriel C, Tazi A, Dramsi S, Trieu-Cuot P, Poyart C. Srr2, a multifaceted adhesin expressed by ST-17 hypervirulent Group B Streptococcus involved in binding to both fibrinogen and plasminogen. Mol Microbiol 2015; 97:1209-22. [PMID: 26094503 DOI: 10.1111/mmi.13097] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2015] [Indexed: 11/30/2022]
Abstract
The Group B Streptococcus (GBS) 'hypervirulent' ST-17 clone is strongly associated with invasive neonatal meningitis. Comparative genome analyses revealed that the serine-rich repeat (Srr) glycoprotein Srr2 is a cell wall-anchored protein specific for ST-17 strains, the non-ST-17 isolates expressing Srr1. Here, we unravel the binding capacity of GBS Srr proteins to relevant components of the host fibrinolysis pathway. We demonstrate that: (i) Srr2 binds plasminogen and plasmin whereas Srr1 does not; (ii) the ability of ST-17 strains to bind fibrinogen reflects a high level surface display of Srr2 combined with a higher affinity of Srr2 than Srr1 to bind this ligand; and (iii) Srr2 binding to host plasma proteins results in the formation of bacterial aggregates that are efficiently endocytosed by phagocytes. Importantly, we show that Srr2 increased bacterial survival to phagocytic killing and bacterial persistence in a murine model of meningitis. We conclude that Srr2 is a multifaceted adhesin used by the ST-17 clone to hijack ligands of the host coagulation system, thereby contributing to bacterial dissemination and invasiveness, and ultimately to meningitis.
Collapse
Affiliation(s)
- Anne Six
- INSERM U 1016, Institut Cochin, team 'Barriers and Pathogens', Paris, F-75014, France.,CNRS UMR 8104, Paris, F-75014, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, F-75014, France.,DHU 'Risques et grossesse', Assistance Publique Hôpitaux de Paris, Paris, France
| | - Samuel Bellais
- INSERM U 1016, Institut Cochin, team 'Barriers and Pathogens', Paris, F-75014, France.,CNRS UMR 8104, Paris, F-75014, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, F-75014, France.,DHU 'Risques et grossesse', Assistance Publique Hôpitaux de Paris, Paris, France
| | - Abdelouhab Bouaboud
- INSERM U 1016, Institut Cochin, team 'Barriers and Pathogens', Paris, F-75014, France.,CNRS UMR 8104, Paris, F-75014, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, F-75014, France.,DHU 'Risques et grossesse', Assistance Publique Hôpitaux de Paris, Paris, France
| | - Agnès Fouet
- INSERM U 1016, Institut Cochin, team 'Barriers and Pathogens', Paris, F-75014, France.,CNRS UMR 8104, Paris, F-75014, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, F-75014, France.,DHU 'Risques et grossesse', Assistance Publique Hôpitaux de Paris, Paris, France.,Centre National de Référence des Streptocoques, Paris, F-75014, France
| | - Christelle Gabriel
- INSERM U 1016, Institut Cochin, team 'Barriers and Pathogens', Paris, F-75014, France.,CNRS UMR 8104, Paris, F-75014, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, F-75014, France.,DHU 'Risques et grossesse', Assistance Publique Hôpitaux de Paris, Paris, France
| | - Asmaa Tazi
- INSERM U 1016, Institut Cochin, team 'Barriers and Pathogens', Paris, F-75014, France.,CNRS UMR 8104, Paris, F-75014, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, F-75014, France.,DHU 'Risques et grossesse', Assistance Publique Hôpitaux de Paris, Paris, France.,Centre National de Référence des Streptocoques, Paris, F-75014, France.,Hôpitaux Universitaires Paris Centre Cochin-Hôtel Dieu-Broca, Assistance Publique Hôpitaux de Paris, Paris, F-75014, France
| | - Shaynoor Dramsi
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram Positif, Paris, F-74016, France.,CNRS ERL3526, Paris, France
| | - Patrick Trieu-Cuot
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram Positif, Paris, F-74016, France.,CNRS ERL3526, Paris, France
| | - Claire Poyart
- INSERM U 1016, Institut Cochin, team 'Barriers and Pathogens', Paris, F-75014, France.,CNRS UMR 8104, Paris, F-75014, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, F-75014, France.,DHU 'Risques et grossesse', Assistance Publique Hôpitaux de Paris, Paris, France.,Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram Positif, Paris, F-74016, France.,CNRS ERL3526, Paris, France.,Centre National de Référence des Streptocoques, Paris, F-75014, France.,Hôpitaux Universitaires Paris Centre Cochin-Hôtel Dieu-Broca, Assistance Publique Hôpitaux de Paris, Paris, F-75014, France
| |
Collapse
|
38
|
The sweet tooth of bacteria: common themes in bacterial glycoconjugates. Microbiol Mol Biol Rev 2015; 78:372-417. [PMID: 25184559 DOI: 10.1128/mmbr.00007-14] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Humans have been increasingly recognized as being superorganisms, living in close contact with a microbiota on all their mucosal surfaces. However, most studies on the human microbiota have focused on gaining comprehensive insights into the composition of the microbiota under different health conditions (e.g., enterotypes), while there is also a need for detailed knowledge of the different molecules that mediate interactions with the host. Glycoconjugates are an interesting class of molecules for detailed studies, as they form a strain-specific barcode on the surface of bacteria, mediating specific interactions with the host. Strikingly, most glycoconjugates are synthesized by similar biosynthesis mechanisms. Bacteria can produce their major glycoconjugates by using a sequential or an en bloc mechanism, with both mechanistic options coexisting in many species for different macromolecules. In this review, these common themes are conceptualized and illustrated for all major classes of known bacterial glycoconjugates, with a special focus on the rather recently emergent field of glycosylated proteins. We describe the biosynthesis and importance of glycoconjugates in both pathogenic and beneficial bacteria and in both Gram-positive and -negative organisms. The focus lies on microorganisms important for human physiology. In addition, the potential for a better knowledge of bacterial glycoconjugates in the emerging field of glycoengineering and other perspectives is discussed.
Collapse
|
39
|
Feltcher ME, Gunawardena HP, Zulauf KE, Malik S, Griffin JE, Sassetti CM, Chen X, Braunstein M. Label-free Quantitative Proteomics Reveals a Role for the Mycobacterium tuberculosis SecA2 Pathway in Exporting Solute Binding Proteins and Mce Transporters to the Cell Wall. Mol Cell Proteomics 2015; 14:1501-16. [PMID: 25813378 DOI: 10.1074/mcp.m114.044685] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Indexed: 01/18/2023] Open
Abstract
Mycobacterium tuberculosis is an example of a bacterial pathogen with a specialized SecA2-dependent protein export system that contributes to its virulence. Our understanding of the mechanistic basis of SecA2-dependent export and the role(s) of the SecA2 pathway in M. tuberculosis pathogenesis has been hindered by our limited knowledge of the proteins exported by the pathway. Here, we set out to identify M. tuberculosis proteins that use the SecA2 pathway for their export from the bacterial cytoplasm to the cell wall. Using label-free quantitative proteomics involving spectral counting, we compared the cell wall and cytoplasmic proteomes of wild type M. tuberculosis to that of a ΔsecA2 mutant. This work revealed a role for the M. tuberculosis SecA2 pathway in the cell wall localization of solute binding proteins that work with ABC transporters to import solutes. Another discovery was a profound effect of SecA2 on the cell wall localization of the Mce1 and Mce4 lipid transporters, which contribute to M. tuberculosis virulence. In addition to the effects on solute binding proteins and Mce transporter export, our label-free quantitative analysis revealed an unexpected relationship between SecA2 and the hypoxia-induced DosR regulon, which is associated with M. tuberculosis latency. Nearly half of the transcriptionally controlled DosR regulon of cytoplasmic proteins were detected at higher levels in the ΔsecA2 mutant versus wild type M. tuberculosis. By increasing the list of M. tuberculosis proteins known to be affected by the SecA2 pathway, this study expands our appreciation of the types of proteins exported by this pathway and guides our understanding of the mechanism of SecA2-dependent protein export in mycobacteria. At the same time, the newly identified SecA2-dependent proteins are helpful for understanding the significance of this pathway to M. tuberculosis virulence and physiology.
Collapse
Affiliation(s)
| | - Harsha P Gunawardena
- §Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, North Carolina, 27599
| | | | - Seidu Malik
- From the ‡Department of Microbiology and Immunology
| | - Jennifer E Griffin
- ¶Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655
| | - Christopher M Sassetti
- ¶Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts 01655; ‖Howard Hughes Medical Institute, Chevy Chase, Maryland, 20815
| | - Xian Chen
- §Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, North Carolina, 27599;
| | | |
Collapse
|
40
|
Buscetta M, Papasergi S, Firon A, Pietrocola G, Biondo C, Mancuso G, Midiri A, Romeo L, Teti G, Speziale P, Trieu-Cuot P, Beninati C. FbsC, a novel fibrinogen-binding protein, promotes Streptococcus agalactiae-host cell interactions. J Biol Chem 2015; 289:21003-21015. [PMID: 24904056 DOI: 10.1074/jbc.m114.553073] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Streptococcus agalactiae (group B Streptococcus or GBS) is a common cause of invasive infections in newborn infants and adults. The ability of GBS to bind human fibrinogen is of crucial importance in promoting colonization and invasion of host barriers. We characterized here a novel fibrinogen-binding protein of GBS, designated FbsC (Gbs0791), which is encoded by the prototype GBS strain NEM316. FbsC, which bears two bacterial immunoglobulin-like tandem repeat domains and a C-terminal cell wall-anchoring motif (LPXTG), was found to be covalently linked to the cell wall by the housekeeping sortase A. Studies using recombinant FbsC indicated that it binds fibrinogen in a dose-dependent and saturable manner, and with moderate affinity. Expression of FbsC was detected in all clinical GBS isolates, except those belonging to the hypervirulent lineage ST17. Deletion of fbsC decreases NEM316 abilities to adhere to and invade human epithelial and endothelial cells, and to form biofilm in vitro. Notably, bacterial adhesion to fibrinogen and fibrinogen binding to bacterial cells were abolished following fbsC deletion in NEM316. Moreover, the virulence of the fbsC deletion mutant and its ability to colonize the brain were impaired in murine models of infection. Finally, immunization with recombinant FbsC significantly protected mice from lethal GBS challenge. In conclusion, FbsC is a novel fibrinogen-binding protein expressed by most GBS isolates that functions as a virulence factor by promoting invasion of epithelial and endothelial barriers. In addition, the protein has significant immunoprotective activity and may be a useful component of an anti-GBS vaccine.
Collapse
|
41
|
RovS and its associated signaling peptide form a cell-to-cell communication system required for Streptococcus agalactiae pathogenesis. mBio 2015; 6:mBio.02306-14. [PMID: 25604789 PMCID: PMC4324310 DOI: 10.1128/mbio.02306-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Bacteria can communicate with each other to coordinate their biological functions at the population level. In a previous study, we described a cell-to-cell communication system in streptococci that involves a transcriptional regulator belonging to the Rgg family and short hydrophobic peptides (SHPs) that act as signaling molecules. Streptococcus agalactiae, an opportunistic pathogenic bacterium responsible for fatal infections in neonates and immunocompromised adults, has one copy of the shp/rgg locus. The SHP-associated Rgg is called RovS in S. agalactiae. In this study, we found that the SHP/RovS cell-to-cell communication system is active in the strain NEM316 of S. agalactiae, and we identified different partners that are involved in this system, such as the Eep peptidase, the PptAB, and the OppA1-F oligopeptide transporters. We also identified a new target gene controlled by this system and reexamined the regulation of a previously proposed target gene, fbsA, in the context of the SHP-associated RovS system. Furthermore, our results are the first to indicate the SHP/RovS system specificity to host liver and spleen using a murine model, which demonstrates its implication in streptococci virulence. Finally, we observed that SHP/RovS regulation influences S. agalactiae's ability to adhere to and invade HepG2 hepatic cells. Hence, the SHP/RovS cell-to-cell communication system appears to be an essential mechanism that regulates pathogenicity in S. agalactiae and represents an attractive target for the development of new therapeutic strategies. IMPORTANCE Rgg regulators and their cognate pheromones, called small hydrophobic peptides (SHPs), are present in nearly all streptococcal species. The general pathways of the cell-to-cell communication system in which Rgg and SHP take part are well understood. However, many other players remain unidentified, and the direct targets of the system, as well as its link to virulence, remain unclear. Here, we identified the different players involved in the SHP/Rgg system in S. agalactiae, which is the leading agent of severe infections in human newborns. We have identified a direct target of the Rgg regulator in S. agalactiae (called RovS) and examined a previously proposed target, all in the context of associated SHP. For the first time, we have also demonstrated the implication of the SHP/RovS mechanism in virulence, as well as its host organ specificity. Thus, this cell-to-cell communication system may represent a future target for S. agalactiae disease treatment.
Collapse
|
42
|
A conserved domain is crucial for acceptor substrate binding in a family of glucosyltransferases. J Bacteriol 2014; 197:510-7. [PMID: 25404702 DOI: 10.1128/jb.02267-14] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Serine-rich repeat glycoproteins (SRRPs) are highly conserved in streptococci and staphylococci. Glycosylation of SRRPs is important for bacterial adhesion and pathogenesis. Streptococcus agalactiae is the leading cause of bacterial sepsis and meningitis among newborns. Srr2, an SRRP from S. agalactiae strain COH1, has been implicated in bacterial virulence. Four genes (gtfA, gtfB, gtfC, and gtfD) located downstream of srr2 share significant homology with genes involved in glycosylation of other SRRPs. We have shown previously that gtfA and gtfB encode two glycosyltransferases, GtfA and GtfB, that catalyze the transfer of GlcNAc residues to the Srr2 polypeptide. However, the function of other glycosyltransferases in glycosylation of Srr2 is unknown. In this study, we determined that GtfC catalyzed the direct transfer of glucosyl residues to Srr2-GlcNAc. The GtfC crystal structure was solved at 2.7 Å by molecular replacement. Structural analysis revealed a loop region at the N terminus as a putative acceptor substrate binding domain. Deletion of this domain rendered GtfC unable to bind to its substrate Srr2-GlcNAc, concurrently abolished the glycosyltransferase activity of GtfC, and also altered glycosylation of Srr2. Furthermore, deletion of the corresponding regions from GtfC homologs also abolished their substrate binding and enzymatic activity, indicating that this region is functionally conserved. In summary, we have determined that GtfC is important for the glycosylation of Srr2 and identified a conserved loop region that is crucial for acceptor substrate binding from GtfC homologs in streptococci. These findings shed new mechanistic insight into this family of glycosyltransferases.
Collapse
|
43
|
The highly conserved domain of unknown function 1792 has a distinct glycosyltransferase fold. Nat Commun 2014; 5:4339. [PMID: 25023666 PMCID: PMC4352575 DOI: 10.1038/ncomms5339] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 06/07/2014] [Indexed: 01/23/2023] Open
Abstract
More than 33,000 glycosyltransferases have been identified. Structural studies, however, have only revealed two distinct glycosyltransferase (GT) folds, GT-A and GT-B. Here we report a 1.34-Å resolution X-ray crystallographic structure of a previously uncharacterized 'domain of unknown function' 1792 (DUF1792) and show that the domain adopts a new fold and is required for glycosylation of a family of serine-rich repeat streptococcal adhesins. Biochemical studies reveal that the domain is a glucosyltransferase, and it catalyses the transfer of glucose to the branch point of the hexasaccharide O-linked to the serine-rich repeat of the bacterial adhesin, Fap1 of Streptococcus parasanguinis. DUF1792 homologues from both Gram-positive and Gram-negative bacteria also exhibit the activity. Thus, DUF1792 represents a new family of glycosyltransferases; therefore, we designate it as a GT-D glycosyltransferase fold. As the domain is highly conserved in bacteria and not found in eukaryotes, it can be explored as a new antibacterial target.
Collapse
|
44
|
Modification of Streptococcus mutans Cnm by PgfS contributes to adhesion, endothelial cell invasion, and virulence. J Bacteriol 2014; 196:2789-97. [PMID: 24837294 DOI: 10.1128/jb.01783-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Expression of the surface protein Cnm has been directly implicated in the ability of certain strains of Streptococcus mutans to bind to collagen and to invade human coronary artery endothelial cells (HCAEC) and in the killing of Galleria mellonella. Sequencing analysis of Cnm(+) strains revealed that cnm is located between the core genes SMU.2067 and SMU.2069. Reverse transcription-PCR (RT-PCR) analysis showed that cnm is cotranscribed with SMU.2067, encoding a putative glycosyltransferase referred to here as PgfS (protein glycosyltransferase of streptococci). Notably, Cnm contains a threonine-rich domain predicted to undergo O-linked glycosylation. The previously shown abnormal migration pattern of Cnm, the presence of the threonine-rich domain, and the molecular linkage of cnm with pgfS lead us to hypothesize that PgfS modifies Cnm. A ΔpgfS strain showed defects in several traits associated with Cnm expression, including collagen binding, HCAEC invasion, and killing of G. mellonella. Western blot analysis revealed that Cnm from the ΔpgfS mutant migrated at a lower molecular weight than that from the parent strain. In addition, Cnm produced by ΔpgfS was highly susceptible to proteinase K degradation, in contrast to the high-molecular-weight Cnm version found in the parent strain. Lectin-binding analyses confirmed the glycosylated nature of Cnm and strongly suggested the presence of N-acetylglucosamine residues attached to Cnm. Based on these findings, the phenotypes observed in ΔpgfS are most likely associated with defects in Cnm glycosylation that affects protein function, stability, or both. In conclusion, this study demonstrates that Cnm is a glycoprotein and that posttranslational modification mediated by PgfS contributes to the virulence-associated phenotypes linked to Cnm.
Collapse
|
45
|
Chaze T, Guillot A, Valot B, Langella O, Chamot-Rooke J, Di Guilmi AM, Trieu-Cuot P, Dramsi S, Mistou MY. O-Glycosylation of the N-terminal region of the serine-rich adhesin Srr1 of Streptococcus agalactiae explored by mass spectrometry. Mol Cell Proteomics 2014; 13:2168-82. [PMID: 24797265 DOI: 10.1074/mcp.m114.038075] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Serine-rich (Srr) proteins exposed at the surface of Gram-positive bacteria are a family of adhesins that contribute to the virulence of pathogenic staphylococci and streptococci. Lectin-binding experiments have previously shown that Srr proteins are heavily glycosylated. We report here the first mass-spectrometry analysis of the glycosylation of Streptococcus agalactiae Srr1. After Srr1 enrichment and trypsin digestion, potential glycopeptides were identified in collision induced dissociation spectra using X! Tandem. The approach was then refined using higher energy collisional dissociation fragmentation which led to the simultaneous loss of sugar residues, production of diagnostic oxonium ions and backbone fragmentation for glycopeptides. This feature was exploited in a new open source software tool (SpectrumFinder) developed for this work. By combining these approaches, 27 glycopeptides corresponding to six different segments of the N-terminal region of Srr1 [93-639] were identified. Our data unambiguously indicate that the same protein residue can be modified with different glycan combinations including N-acetylhexosamine, hexose, and a novel modification that was identified as O-acetylated-N-acetylhexosamine. Lectin binding and monosaccharide composition analysis strongly suggested that HexNAc and Hex correspond to N-acetylglucosamine and glucose, respectively. The same protein segment can be modified with a variety of glycans generating a wide structural diversity of Srr1. Electron transfer dissociation was used to assign glycosylation sites leading to the unambiguous identification of six serines and one threonine residues. Analysis of purified Srr1 produced in mutant strains lacking accessory glycosyltransferase encoding genes demonstrates that O-GlcNAcylation is an initial step in Srr1 glycosylation that is likely required for subsequent decoration with Hex. In summary, our data obtained by a combination of fragmentation mass spectrometry techniques associated to a new software tool, demonstrate glycosylation heterogeneity of Srr1, characterize a new protein modification, and identify six glycosylation sites located in the N-terminal region of the protein.
Collapse
Affiliation(s)
- Thibault Chaze
- From the ‡INRA, MICALIS UMR-1319, 78352 Jouy-en-Josas cedex, France; §AgroParisTech, MICALIS UMR-1319, 78352 Jouy-en-Josas cedex, France; ¶¶Institut Pasteur, Unité de Spectrométrie de Masse Structurale et Protéomique, 28 rue du Dr Roux, 75015 Paris, France
| | - Alain Guillot
- ¶INRA, PAPPSO, MICALIS UMR-1319, 78352 Jouy en Josas cedex, France
| | - Benoît Valot
- ‖INRA, PAPPSO, Génétique végétale UMR-320, Ferme du Moulon, 91190 Gif sur Yvette, France
| | - Olivier Langella
- ‖INRA, PAPPSO, Génétique végétale UMR-320, Ferme du Moulon, 91190 Gif sur Yvette, France
| | - Julia Chamot-Rooke
- ¶¶Institut Pasteur, Unité de Spectrométrie de Masse Structurale et Protéomique, 28 rue du Dr Roux, 75015 Paris, France; ‖‖CNRS UMR 3528, Institut Pasteur, 28 rue du Dr Roux, 75015 Paris, France
| | - Anne-Marie Di Guilmi
- **CEA, Institut de Biologie Structurale Jean-Pierre Ebel, F-38027 Grenoble, France
| | - Patrick Trieu-Cuot
- ‡‡Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram+, 28, rue du Dr Roux, 75015 Paris, France; §§Centre National de la Recherche Scientifique, CNRS ERL3526, Paris, France
| | - Shaynoor Dramsi
- ‡‡Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram+, 28, rue du Dr Roux, 75015 Paris, France; §§Centre National de la Recherche Scientifique, CNRS ERL3526, Paris, France
| | - Michel-Yves Mistou
- From the ‡INRA, MICALIS UMR-1319, 78352 Jouy-en-Josas cedex, France; §AgroParisTech, MICALIS UMR-1319, 78352 Jouy-en-Josas cedex, France;
| |
Collapse
|
46
|
Bensing BA, Seepersaud R, Yen YT, Sullam PM. Selective transport by SecA2: an expanding family of customized motor proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:1674-86. [PMID: 24184206 DOI: 10.1016/j.bbamcr.2013.10.019] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 10/20/2013] [Accepted: 10/23/2013] [Indexed: 01/22/2023]
Abstract
The SecA2 proteins are a special class of transport-associated ATPases that are related to the SecA component of the general Sec system, and are found in an increasingly large number of Gram-positive bacterial species. The SecA2 substrates are typically linked to the cell wall, but may be lipid-linked, peptidoglycan-linked, or non-covalently associated S-layer proteins. These substrates can have a significant impact on virulence of pathogenic organisms, but may also aid colonization by commensals. The SecA2 orthologues range from being highly similar to their SecA paralogues, to being distinctly different in apparent structure and function. Two broad classes of SecA2 are evident. One transports multiple substrates, and may interact with the general Sec system, or with an as yet unidentified transmembrane channel. The second type transports a single substrate, and is a component of the accessory Sec system, which includes the SecY paralogue SecY2 along with the accessory Sec proteins Asp1-3. Recent studies indicate that the latter three proteins may have a unique role in coordinating post-translational modification of the substrate with transport by SecA2. Comparative functional and phylogenetic analyses suggest that each SecA2 may be uniquely adapted for a specific type of substrate. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
Collapse
Affiliation(s)
- Barbara A Bensing
- San Francisco Veterans Affairs Medical Center and the University of California, San Francisco, CA 94121, USA.
| | - Ravin Seepersaud
- San Francisco Veterans Affairs Medical Center and the University of California, San Francisco, CA 94121, USA
| | - Yihfen T Yen
- San Francisco Veterans Affairs Medical Center and the University of California, San Francisco, CA 94121, USA
| | - Paul M Sullam
- San Francisco Veterans Affairs Medical Center and the University of California, San Francisco, CA 94121, USA
| |
Collapse
|
47
|
Brega S, Caliot E, Trieu-Cuot P, Dramsi S. SecA localization and SecA-dependent secretion occurs at new division septa in group B Streptococcus. PLoS One 2013; 8:e65832. [PMID: 23762438 PMCID: PMC3676364 DOI: 10.1371/journal.pone.0065832] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 04/29/2013] [Indexed: 11/19/2022] Open
Abstract
Exported proteins of Streptococcus agalactiae (GBS), which include proteins localized to the bacterial surface or secreted into the extracellular environment, are key players for commensal and pathogenic interactions in the mammalian host. These proteins are transported across the cytoplasmic membrane via the general SecA secretory pathway and those containing the so-called LPXTG sorting motif are covalently attached to the peptidoglycan by sortase A. How SecA, sortase A, and LPXTG proteins are spatially distributed in GBS is not known. In the close relative Streptococcus pyogenes, it was shown that presence of the YSIRKG/S motif (literally YSIRKX3Gx2S) in the signal peptide (SP) constitutes the targeting information for secretion at the septum. Here, using conventional and deconvolution immunofluorescence analyses, we have studied in GBS strain NEM316 the localization of SecA, SrtA, and the secreted protein Bsp whose signal peptide contains a canonical YSIRKG/S motif (YSLRKykfGlaS). Replacing the SP of Bsp with four other SPs containing or not the YSIRKG/S motif did not alter the localized secretion of Bsp at the equatorial ring. Our results indicate that secretion and cell wall-anchoring machineries are localized at the division septum. Cell wall- anchored proteins displayed polar (PilB, Gbs0791), punctuate (CspA) or uniform distribution (Alp2) on the bacterial surface. De novo secretion of Gbs0791 following trypsin treatment indicates that it is secreted at the septum, then redistributed along the lateral sides, and finally accumulated to the poles. We conclude that the ±YSIRK SP rule driving compartimentalized secretion is not true in S. agalactiae.
Collapse
Affiliation(s)
- Sara Brega
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS, ERL 3526, Paris, France
| | - Elise Caliot
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS, ERL 3526, Paris, France
| | - Patrick Trieu-Cuot
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS, ERL 3526, Paris, France
| | - Shaynoor Dramsi
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS, ERL 3526, Paris, France
- * E-mail:
| |
Collapse
|
48
|
Seo HS, Xiong YQ, Sullam PM. Role of the serine-rich surface glycoprotein Srr1 of Streptococcus agalactiae in the pathogenesis of infective endocarditis. PLoS One 2013; 8:e64204. [PMID: 23717569 PMCID: PMC3662765 DOI: 10.1371/journal.pone.0064204] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 04/12/2013] [Indexed: 11/26/2022] Open
Abstract
The binding of bacteria to fibrinogen and platelets are important events in the pathogenesis of infective endocarditis. Srr1 is a serine-rich repeat glycoprotein of Streptococcus agalactiae that binds directly to the Aα chain of human fibrinogen. To assess the impact of Srr1 on the pathogenesis of endocarditis due to S. agalactiae, we first examined the binding of this organism to immobilized human platelets. Strains expressing Srr1 had significantly higher levels of binding to human platelets in vitro, as compared with isogenic Δsrr1 mutants. In addition, platelet binding was inhibited by pretreatment with anti-fibrinogen IgG or purified Srr1 binding region. To assess the contribution of Srr1 to pathogenicity, we compared the relative virulence of S. agalactiae NCTC 10/84 strain and its Δsrr1 mutant in a rat model of endocarditis, where animals were co-infected with the WT and the mutant strains at a 1∶1 ratio. At 72 h post-infection, bacterial densities (CFU/g) of the WT strain within vegetations, kidneys, and spleens were significantly higher, as compared with the Δsrr1 mutant. These results indicate that Srr1 contributes to the pathogenesis of endocarditis due to S. agalactiae, at least in part through its role in fibrinogen-mediated platelet binding.
Collapse
Affiliation(s)
- Ho Seong Seo
- Division of Infectious Diseases, Veterans Affairs Medical Center and the University of California San Francisco, San Francisco, California, United States of America
| | - Yan Q. Xiong
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
- Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Paul M. Sullam
- Division of Infectious Diseases, Veterans Affairs Medical Center and the University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
| |
Collapse
|
49
|
Diversity of seM in Streptococcus equi subsp. equi isolated from strangles outbreaks. Vet Microbiol 2013; 162:663-669. [DOI: 10.1016/j.vetmic.2012.09.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 09/06/2012] [Accepted: 09/08/2012] [Indexed: 11/22/2022]
|
50
|
Protein export by the mycobacterial SecA2 system is determined by the preprotein mature domain. J Bacteriol 2012. [PMID: 23204463 DOI: 10.1128/jb.02032-12] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
At the core of the bacterial general secretion (Sec) pathway is the SecA ATPase, which powers translocation of unfolded preproteins containing Sec signal sequences through the SecYEG membrane channel. Mycobacteria have two nonredundant SecA homologs: SecA1 and SecA2. While the essential SecA1 handles "housekeeping" export, the nonessential SecA2 exports a subset of proteins and is required for Mycobacterium tuberculosis virulence. Currently, it is not understood how SecA2 contributes to Sec export in mycobacteria. In this study, we focused on identifying the features of two SecA2 substrates that target them to SecA2 for export, the Ms1704 and Ms1712 lipoproteins of the model organism Mycobacterium smegmatis. We found that the mature domains of Ms1704 and Ms1712, not the N-terminal signal sequences, confer SecA2-dependent export. We also demonstrated that the lipid modification and the extreme N terminus of the mature protein do not impart the requirement for SecA2 in export. We further showed that the Ms1704 mature domain can be efficiently exported by the twin-arginine translocation (Tat) pathway. Because the Tat system exports only folded proteins, this result implies that SecA2 substrates can fold in the cytoplasm and suggests a putative role of SecA2 in enabling export of such proteins. Thus, the mycobacterial SecA2 system may represent another way that bacteria solve the problem of exporting proteins that can fold in the cytoplasm.
Collapse
|