1
|
Bedree JK, Bourgeois J, Balani P, Cen L, Hendrickson EL, Kerns KA, Camilli A, McLean JS, Shi W, He X. Identifying essential genes in Schaalia odontolytica using a highly-saturated transposon library. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.17.604004. [PMID: 39071323 PMCID: PMC11275721 DOI: 10.1101/2024.07.17.604004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
The unique epibiotic-parasitic relationship between Nanosynbacter lyticus type strain TM7x, a member of the newly identified Candidate Phyla Radiation, now referred to as Patescibacteria, and its basibiont, Schaalia odontolytica strain XH001 (formerly Actinomyces odontolyticus), require more powerful genetic tools for deeper understanding of the genetic underpinnings that mediate their obligate relationship. Previous studies have mainly characterized the genomic landscape of XH001 during or post TM7x infection through comparative genomic or transcriptomic analyses followed by phenotypic analysis. Comprehensive genetic dissection of the pair is currently cumbersome due to the lack of robust genetic tools in TM7x. However, basic genetic tools are available for XH001 and this study expands the current genetic toolset by developing high-throughput transposon insertion sequencing (Tn-seq). Tn-seq was employed to screen for essential genes in XH001 under laboratory conditions. A highly saturated Tn-seq library was generated with nearly 660,000 unique insertion mutations, averaging one insertion every 2-3 nucleotides. 203 genes, 10.5% of the XH001 genome, were identified as putatively essential.
Collapse
Affiliation(s)
- Joseph K Bedree
- Section of Oral Biology, Division of Oral Biology and Medicine, School of Dentistry, University of California-Los Angeles, Los Angeles, CA, 90095
- Department of Microbiology, The ADA Forsyth Institute; Cambridge, MA, 02142
| | - Jacob Bourgeois
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - Pooja Balani
- Department of Microbiology, The ADA Forsyth Institute; Cambridge, MA, 02142
- Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115
| | - Lujia Cen
- Department of Microbiology, The ADA Forsyth Institute; Cambridge, MA, 02142
| | - Erik L Hendrickson
- Department of Periodontics, School of Dentistry, University of Washington, Seattle, WA, 98195
| | - Kristopher A Kerns
- Department of Periodontics, School of Dentistry, University of Washington, Seattle, WA, 98195
| | - Andrew Camilli
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - Jeffrey S McLean
- Department of Periodontics, School of Dentistry, University of Washington, Seattle, WA, 98195
| | - Wenyuan Shi
- Department of Microbiology, The ADA Forsyth Institute; Cambridge, MA, 02142
| | - Xuesong He
- Department of Microbiology, The ADA Forsyth Institute; Cambridge, MA, 02142
| |
Collapse
|
2
|
Nappi F, Avtaar Singh SS, Jitendra V, Fiore A. Bridging Molecular and Clinical Sciences to Achieve the Best Treatment of Enterococcus faecalis Endocarditis. Microorganisms 2023; 11:2604. [PMID: 37894262 PMCID: PMC10609379 DOI: 10.3390/microorganisms11102604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/14/2023] [Accepted: 09/26/2023] [Indexed: 10/29/2023] Open
Abstract
Enterococcus faecalis (E. faecalis) is a commensal bacterium that causes various infections in surgical sites, the urinary tract, and blood. The bacterium is becoming a significant concern because it tends to affect the elderly population, which has a high prevalence of undiagnosed degenerative valvular disease and is often subjected to invasive procedures and implanted medical devices. The bacterium's actions are influenced by specific characteristics like pili activity and biofilm formation. This resistance significantly impedes the effectiveness of numerous antibiotic therapies, particularly in cases of endocarditis. While current guidelines recommend antimicrobial therapy, the emergence of resistant strains has introduced complexity in managing these patients, especially with the increasing use of transcatheter therapies for those who are not suitable for surgery. Presentations of the condition are often varied and associated with generalised symptoms, which may pose a diagnostic challenge. We share our encounter with a case study that concerns an octogenarian who had a TAVI valve and developed endocarditis. We also conducted a literature review to identify the essential treatment algorithms for such cases.
Collapse
Affiliation(s)
- Francesco Nappi
- Department of Cardiac Surgery, Centre Cardiologique du Nord, 93200 Saint-Denis, France
| | | | - Vikram Jitendra
- Department of Cardiothoracic Surgery, Aberdeen Royal Infirmary, Aberdeen AB25 2ZN, UK;
| | - Antonio Fiore
- Department of Cardiac Surgery, Hôpitaux Universitaires Henri Mondor, Assistance Publique-Hôpitaux de Paris, 94000 Creteil, France;
| |
Collapse
|
3
|
Yadav RK, Krishnan V. New structural insights into the
PI
‐2 pilus from
Streptococcus oralis
, an early dental plaque colonizer. FEBS J 2022; 289:6342-6366. [DOI: 10.1111/febs.16527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 04/20/2022] [Accepted: 05/10/2022] [Indexed: 11/29/2022]
Affiliation(s)
- Rajnesh Kumari Yadav
- Laboratory of Structural Microbiology, Regional Centre for Biotechnology NCR Biotech Science Cluster Faridabad India
- School of Biotechnology KIIT University Odisha India
| | - Vengadesan Krishnan
- Laboratory of Structural Microbiology, Regional Centre for Biotechnology NCR Biotech Science Cluster Faridabad India
| |
Collapse
|
4
|
Shoji M, Shibata S, Sueyoshi T, Naito M, Nakayama K. Biogenesis of Type V pili. Microbiol Immunol 2020; 64:643-656. [DOI: 10.1111/1348-0421.12838] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/11/2020] [Accepted: 08/13/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Mikio Shoji
- Department of Microbiology and Oral Infection, Graduate School of Biomedical Sciences Nagasaki University Nagasaki Nagasaki Japan
| | - Satoshi Shibata
- Molecular Cryo‐Electron Microscopy Unit Okinawa Institute of Science and Technology Graduate University Onna Okinawa Japan
| | - Takayuki Sueyoshi
- Department of Microbiology and Oral Infection, Graduate School of Biomedical Sciences Nagasaki University Nagasaki Nagasaki Japan
| | - Mariko Naito
- Department of Microbiology and Oral Infection, Graduate School of Biomedical Sciences Nagasaki University Nagasaki Nagasaki Japan
| | - Koji Nakayama
- Department of Microbiology and Oral Infection, Graduate School of Biomedical Sciences Nagasaki University Nagasaki Nagasaki Japan
| |
Collapse
|
5
|
Ramirez NA, Das A, Ton-That H. New Paradigms of Pilus Assembly Mechanisms in Gram-Positive Actinobacteria. Trends Microbiol 2020; 28:999-1009. [PMID: 32499101 DOI: 10.1016/j.tim.2020.05.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 05/08/2020] [Accepted: 05/14/2020] [Indexed: 02/06/2023]
Abstract
Adhesive pili in Gram-positive bacteria represent a variety of extracellular multiprotein polymers that mediate bacterial colonization of specific host tissues and associated pathogenesis. Pili are assembled in two distinct but coupled steps, an orderly crosslinking of pilin monomers and subsequent anchoring of the polymer to peptidoglycan, catalyzed by two transpeptidase enzymes - the pilus-specific sortase and the housekeeping sortase. Here, we review this biphasic assembly mechanism based on studies of two prototypical models, the heterotrimeric pili in Corynebacterium diphtheriae and the heterodimeric pili in Actinomyces oris, highlighting some newly emerged basic paradigms. The disparate mechanisms of protein ligation mediated by the pilus-specific sortase and the spatial positioning of adhesive pili on the cell surface modulated by the housekeeping sortase are among the notable highlights.
Collapse
Affiliation(s)
- Nicholas A Ramirez
- Molecular Biology Institute, University of California, Los Angeles, CA, USA
| | - Asis Das
- Department of Medicine, Neag Comprehensive Cancer Center, University of Connecticut Health Center, Farmington, CT, USA
| | - Hung Ton-That
- Molecular Biology Institute, University of California, Los Angeles, CA, USA; Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, CA, USA.
| |
Collapse
|
6
|
Khare B, V L Narayana S. Pilus biogenesis of Gram-positive bacteria: Roles of sortases and implications for assembly. Protein Sci 2017; 26:1458-1473. [PMID: 28493331 DOI: 10.1002/pro.3191] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 04/28/2017] [Accepted: 05/03/2017] [Indexed: 12/26/2022]
Abstract
Successful adherence, colonization, and survival of Gram-positive bacteria require surface proteins, and multiprotein assemblies called pili. These surface appendages are attractive pharmacotherapeutic targets and understanding their assembly mechanisms is essential for identifying a new class of 'anti-infectives' that do not elicit microbial resistance. Molecular details of the Gram-negative pilus assembly are available indepth, but the Gram-positive pilus biogenesis is still an emerging field and investigations continue to reveal novel insights into this process. Pilus biogenesis in Gram-positive bacteria is a biphasic process that requires enzymes called pilus-sortases for assembly and a housekeeping sortase for covalent attachment of the assembled pilus to the peptidoglycan cell wall. Emerging structural and functional data indicate that there are at least two groups of Gram-positive pili, which require either the Class C sortase or Class B sortase in conjunction with LepA/SipA protein for major pilin polymerization. This observation suggests two distinct modes of sortase-mediated pilus biogenesis in Gram-positive bacteria. Here we review the structural and functional biology of the pilus-sortases from select streptococcal pilus systems and their role in Gram-positive pilus assembly.
Collapse
Affiliation(s)
- Baldeep Khare
- Center for Structural Biology, School of Optometry, University of Alabama at Birmingham, Birmingham, USA
| | - Sthanam V L Narayana
- Center for Structural Biology, School of Optometry, University of Alabama at Birmingham, Birmingham, USA
| |
Collapse
|
7
|
Mulé MP, Giacalone D, Lawlor K, Golden A, Cook C, Lott T, Aksten E, O'Toole GA, Bergeron LJ. Iron-dependent gene expression in Actinomyces oris. J Oral Microbiol 2015; 7:29800. [PMID: 26685151 PMCID: PMC4684579 DOI: 10.3402/jom.v7.29800] [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: 09/21/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 11/21/2022] Open
Abstract
Background Actinomyces oris is a Gram-positive bacterium that has been associated with healthy and diseased sites in the human oral cavity. Most pathogenic bacteria require iron to survive, and in order to acquire iron in the relatively iron-scarce oral cavity A. oris has been shown to produce iron-binding molecules known as siderophores. The genes encoding these siderophores and transporters are thought to be regulated by the amount of iron in the growth medium and by the metal-dependent repressor, AmdR, which we showed previously binds to the promoter of proposed iron-regulated genes. Objective The purpose of this study was to characterize siderophore and associated iron transport systems in A. oris.
Design We examined gene expression of the putative iron transport genes fetA and sidD in response to low- and high-iron environments. One of these genes, sidD, encoding a putative Fe ABC transporter protein, was insertionally inactivated and was examined for causing growth defects. To gain a further understanding of the role of iron metabolism in oral diseases, clinical isolates of Actinomyces spp. were examined for the presence of the gene encoding AmdR, a proposed global regulator of iron-dependent gene expression in A. oris.
Results When A. oris was grown under iron-limiting conditions, the genes encoding iron/siderophore transporters fetA and sidD showed increased expression. One of these genes (sidD) was mutated, and the sidD::Km strain exhibited a 50% reduction in growth in late log and stationary phase cells in media that contained iron. This growth defect was restored when the sidD gene was provided in a complemented strain. We were able to isolate the AmdR-encoding gene in seven clinical isolates of Actinomyces. When these protein sequences were aligned to the laboratory strain, there was a high degree of sequence similarity. Conclusions The growth of the sidD::Km mutant in iron-replete medium mirrored the growth of the wild-type strain grown in iron-limiting medium, suggesting that the sidD::Km mutant was compromised in iron uptake. The known iron regulator AmdR is well conserved in clinical isolates of A. oris. This work provides additional insight into iron metabolism in this important oral microbe.
Collapse
Affiliation(s)
- Matthew P Mulé
- Department of Biology, New England College, Henniker, NH, USA
| | - David Giacalone
- Department of Biology, New England College, Henniker, NH, USA
| | - Kayla Lawlor
- Department of Biology, New England College, Henniker, NH, USA
| | - Alexa Golden
- Department of Biology, New England College, Henniker, NH, USA
| | - Caroline Cook
- Department of Biology, New England College, Henniker, NH, USA
| | - Thomas Lott
- Department of Biology, New England College, Henniker, NH, USA
| | | | - George A O'Toole
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Lori J Bergeron
- Department of Biology, New England College, Henniker, NH, USA;
| |
Collapse
|
8
|
Schneewind O, Missiakas D. Sec-secretion and sortase-mediated anchoring of proteins in Gram-positive bacteria. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1843:1687-97. [PMID: 24269844 PMCID: PMC4031296 DOI: 10.1016/j.bbamcr.2013.11.009] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 11/01/2013] [Accepted: 11/13/2013] [Indexed: 01/17/2023]
Abstract
Signal peptide-driven secretion of precursor proteins directs polypeptides across the plasma membrane of bacteria. Two pathways, Sec- and SRP-dependent, converge at the SecYEG translocon to thread unfolded precursor proteins across the membrane, whereas folded preproteins are routed via the Tat secretion pathway. Gram-positive bacteria lack an outer membrane and are surrounded by a rigid layer of peptidoglycan. Interactions with their environment are mediated by proteins that are retained in the cell wall, often through covalent attachment to the peptidoglycan. In this review, we describe the mechanisms for both Sec-dependent secretion and sortase-dependent assembly of proteins in the envelope of Gram-positive bacteria. 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)
- Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA.
| | | |
Collapse
|
9
|
Wide distribution of virulence genes among Enterococcus faecium and Enterococcus faecalis clinical isolates. ScientificWorldJournal 2014; 2014:623174. [PMID: 25147855 PMCID: PMC4124215 DOI: 10.1155/2014/623174] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 06/13/2014] [Accepted: 06/19/2014] [Indexed: 12/02/2022] Open
Abstract
Enterococcus, a Gram-positive facultative anaerobic cocci belonging to the lactic acid bacteria of the phylum Firmicutes, is known to be able to resist a wide range of hostile conditions such as different pH levels, high concentration of NaCl (6.5%), and the extended temperatures between 5°C and 65°C. Despite being the third most common nosocomial pathogen, our understanding on its virulence factors is still poorly understood. The current study was aimed to determine the prevalence of different virulence genes in Enterococcus faecalis and Enterococcus faecium. For this purpose, 79 clinical isolates of Malaysian enterococci were evaluated for the presence of virulence genes. pilB, fms8, efaAfm, and sgrA genes are prevalent in all clinical isolates. In conclusion, the pathogenicity of E. faecalis and E. faecium could be associated with different virulence factors and these genes are widely distributed among the enterococcal species.
Collapse
|
10
|
Oxaran V, Ledue-Clier F, Dieye Y, Herry JM, Péchoux C, Meylheuc T, Briandet R, Juillard V, Piard JC. Pilus biogenesis in Lactococcus lactis: molecular characterization and role in aggregation and biofilm formation. PLoS One 2012; 7:e50989. [PMID: 23236417 PMCID: PMC3516528 DOI: 10.1371/journal.pone.0050989] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Accepted: 10/29/2012] [Indexed: 02/07/2023] Open
Abstract
The genome of Lactococcus lactis strain IL1403 harbors a putative pilus biogenesis cluster consisting of a sortase C gene flanked by 3 LPxTG protein encoding genes (yhgD, yhgE, and yhhB), called here pil. However, pili were not detected under standard growth conditions. Over-expression of the pil operon resulted in production and display of pili on the surface of lactococci. Functional analysis of the pilus biogenesis machinery indicated that the pilus shaft is formed by oligomers of the YhgE pilin, that the pilus cap is formed by the YhgD pilin and that YhhB is the basal pilin allowing the tethering of the pilus fibers to the cell wall. Oligomerization of pilin subunits was catalyzed by sortase C while anchoring of pili to the cell wall was mediated by sortase A. Piliated L. lactis cells exhibited an auto-aggregation phenotype in liquid cultures, which was attributed to the polymerization of major pilin, YhgE. The piliated lactococci formed thicker, more aerial biofilms compared to those produced by non-piliated bacteria. This phenotype was attributed to oligomers of YhgE. This study provides the first dissection of the pilus biogenesis machinery in a non-pathogenic Gram-positive bacterium. Analysis of natural lactococci isolates from clinical and vegetal environments showed pili production under standard growth conditions. The identification of functional pili in lactococci suggests that the changes they promote in aggregation and biofilm formation may be important for the natural lifestyle as well as for applications in which these bacteria are used.
Collapse
Affiliation(s)
- Virginie Oxaran
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Florence Ledue-Clier
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Yakhya Dieye
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Jean-Marie Herry
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | | | - Thierry Meylheuc
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Romain Briandet
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Vincent Juillard
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
| | - Jean-Christophe Piard
- INRA, UMR1319 Micalis, Domaine de Vilvert, Jouy-en-Josas, France
- Agro ParisTech, UMR 1319 Micalis, Jouy-en-Josas, France
- * E-mail:
| |
Collapse
|
11
|
Persson K, Esberg A, Claesson R, Strömberg N. The pilin protein FimP from Actinomyces oris: crystal structure and sequence analyses. PLoS One 2012; 7:e48364. [PMID: 23118994 PMCID: PMC3485203 DOI: 10.1371/journal.pone.0048364] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 09/24/2012] [Indexed: 11/19/2022] Open
Abstract
The Actinomyces oris type-1 pili are important for the initial formation of dental plaque by binding to salivary proteins that adhere to the tooth surface. Here we present the X-ray structure of FimP, the protein that is polymerized into the type-1 pilus stalk, assisted by a pili-specific sortase. FimP consists of three tandem IgG-like domains. The middle and C-terminal domains contain one autocatalyzed intramolecular isopeptide bond each, a feature used by Gram-positive bacteria for stabilization of surface proteins. While the N-terminal domain harbours all the residues necessary for forming an isopeptide bond, no such bond is observed in the crystal structure of this unpolymerized form of FimP. The monomer is further stabilized by one disulfide bond each in the N- and C-terminal domains as well as by a metal-coordinated loop protruding from the C-terminal domain. A lysine, predicted to be crucial for FimP polymerization by covalent attachment to a threonine from another subunit, is located at the rim of a groove lined with conserved residues. The groove may function as a docking site for the sortase-FimP complex. We also present sequence analyses performed on the genes encoding FimP as well as the related FimA, obtained from clinical isolates.
Collapse
|
12
|
Characterization of the SpaCBA pilus fibers in the probiotic Lactobacillus rhamnosus GG. Appl Environ Microbiol 2012; 78:2337-44. [PMID: 22247175 DOI: 10.1128/aem.07047-11] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactobacillus rhamnosus GG is a human intestinal isolate that has been studied intensively because of its probiotic properties. We have previously shown that L. rhamnosus GG produces proteinaceous pili that earlier had been observed only in Gram-positive pathogens (M. Kankainen et al., Proc. Natl. Acad. Sci. U. S. A. 106:17193-17198, 2009). These pili were found to be encoded by the spaCBA gene cluster, and the pilus-associated SpaC pilin was shown to confer on the cells a mucus-binding ability. In addition to the spaCBA cluster, another putative pilus cluster, spaFED, was predicted from the L. rhamnosus GG genome sequence. Herein, we show that only SpaCBA pili are produced by L. rhamnosus, and we describe a detailed analysis of cell wall-associated and affinity-purified SpaCBA pili by Western blotting and immunogold electron microscopy. Our results indicate that SpaCBA pili are heterotrimeric protrusions with a SpaA subunit as the shaft-forming major pilin. Only a few SpaB subunits could be observed in pilus fibers. Instead, SpaB pilins were found at pilus bases, as assessed by immunogold double labeling of thin sections of cells, suggesting that SpaB is involved in the termination of pilus assembly. The SpaC adhesin was present along the whole pilus length at numbers nearly equaling those of SpaA. The relative amount and uniform distribution of SpaC within pili not only makes it possible to exert both long-distance and intimate contact with host tissue but also provides mucus-binding strength, which explains the prolonged intestinal residency times observed for L. rhamnosus GG compared to that of nonpiliated lactobacilli.
Collapse
|
13
|
Persson K. Crystallization of the fimbrial protein FimP from Actinomyces oris and of a triple Ile-to-Met mutant engineered to facilitate selenomethionine labelling. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:1207-10. [PMID: 22102028 PMCID: PMC3212363 DOI: 10.1107/s1744309111025929] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 06/30/2011] [Indexed: 11/10/2022]
Abstract
Actinomyces oris is an oral bacterium important for the development of dental plaque. It expresses two forms of fimbriae: type 1 and type 2. FimP, which is the fimbrial protein that is polymerized into the stalk of the type 1 fimbriae, was cloned, overexpressed and crystallized. X-ray data were collected and processed to 2.2 Å resolution. The crystals belonged to space group P2(1)2(1)2, with one molecule in the asymmetric unit. To facilitate structure determination using single anomalous dispersion, three methionines were introduced by site-directed mutagenesis. Crystals of selenomethionine-labelled protein were obtained by streak-seeding and diffracted to 2.0 Å resolution.
Collapse
Affiliation(s)
- Karina Persson
- Department of Odontology, Umeå University, SE-901 87 Umeå, Sweden.
| |
Collapse
|
14
|
Dual function of a tip fimbrillin of Actinomyces in fimbrial assembly and receptor binding. J Bacteriol 2011; 193:3197-206. [PMID: 21531799 DOI: 10.1128/jb.00173-11] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Interaction of Actinomyces oris with salivary proline-rich proteins (PRPs), which serve as fimbrial receptors, involves type 1 fimbriae. Encoded by the gene locus fimQ-fimP-srtC1, the type 1 fimbria is comprised of the fimbrial shaft FimP and the tip fimbrillin FimQ. Fimbrial polymerization requires the fimbria-specific sortase SrtC1, which catalyzes covalent linkage of fimbrial subunits. Using genetics, biochemical methods, and electron microscopy, we provide evidence that the tip fimbrillin, FimQ, is involved in fimbrial assembly and interaction with PRPs. Specifically, while deletion of fimP completely abolished the type 1 fimbrial structures, surface display of monomeric FimQ was not affected by this mutation. Surprisingly, deletion of fimQ significantly reduced surface assembly of the type 1 fimbriae. This defect was rescued by recombinant FimQ ectopically expressed from a plasmid. In agreement with the role of type 1 fimbriae in binding to PRPs, aggregation of A. oris with PRP-coated beads was abrogated in cells lacking srtC1 or fimP. This aggregation defect of the ΔfimP mutant was mainly due to significant reduction of FimQ on the bacterial surface, as the aggregation was not observed in a strain lacking fimQ. Increasing expression of FimQ in the ΔfimP mutant enhanced aggregation, while overexpression of FimP in the ΔfimQ mutant did not. Furthermore, recombinant FimQ, not FimP, bound surface-associated PRPs in a dose-dependent manner. Thus, not only does FimQ function as the major adhesin of the type 1 fimbriae, it also plays an important role in fimbrial assembly.
Collapse
|
15
|
Soriani M, Telford JL. Relevance of pili in pathogenic streptococci pathogenesis and vaccine development. Future Microbiol 2010; 5:735-47. [PMID: 20441546 DOI: 10.2217/fmb.10.37] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A common mechanism used by bacteria to initiate adhesion to host tissues during colonization is the expression of long filamentous structures extending from their surface. These structures, known as pili or fimbriae, were initially identified in Gram-negative bacteria, and are typically formed by noncovalent interactions between pilin subunits. Pili have only recently been described in Gram-positive bacteria. In particular, in pathogenic streptococci the proteinaceous components of pili are covalently polymerized by the action of sortase enzymes similar to those involved in the covalent attachment of Gram-positive surface proteins to the peptidoglycan cell wall. With great relevance to the development of strategies to combat Gram-positive-associated infections, pilus components from pathogenic streptococci have been shown to induce protective immunity in mouse models of streptococcal disease. In addition, recent papers have created new perspectives on the role of such organelles in streptococcal pathogenesis, from the involvement in colonization and biofilm formation to translocation of tissue barriers. All this information makes the characterization of pili a hot scientific issue that we believe will lead to important future developments in understanding bacterial dynamics that lead to successful occupation of microbial niches.
Collapse
Affiliation(s)
- Marco Soriani
- Microbial Molecular Biology Department, Novartis Vaccines, Via Fiorentina 1, 53100 Siena, Italy
| | | |
Collapse
|
16
|
Allelic exchange in Actinomyces oris with mCherry fluorescence counterselection. Appl Environ Microbiol 2010; 76:5987-9. [PMID: 20601506 DOI: 10.1128/aem.00811-10] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Described here is a method for facile generation of markerless gene deletion mutants of Actinomyces oris. Homologous integration of a nonreplicative vector carrying a gene exchange cassette into the bacterial chromosome was selected for by using mCherry fluorescence and resistance to kanamycin. Completion of allelic replacement was counterselected for by using loss of fluorescence.
Collapse
|
17
|
Mishra A, Wu C, Yang J, Cisar JO, Das A, Ton-That H. The Actinomyces oris type 2 fimbrial shaft FimA mediates co-aggregation with oral streptococci, adherence to red blood cells and biofilm development. Mol Microbiol 2010; 77:841-54. [PMID: 20545853 DOI: 10.1111/j.1365-2958.2010.07252.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Interbacterial interactions between oral streptococci and actinomyces and their adherence to tooth surface and the associated host cells are key early events that promote development of the complex oral biofilm referred to as dental plaque. These interactions depend largely on a lectin-like activity associated with the Actinomyces oris type 2 fimbria, a surface structure assembled by sortase (SrtC2)-dependent polymerization of the shaft and tip fimbrillins, FimA and FimB respectively. To dissect the function of specific fimbrillins in various adherence processes, we have developed a convenient new technology for generating unmarked deletion mutants of A. oris. Here, we show that the fimB mutant, which produced type 2 fimbriae composed only of FimA, like the wild type co-aggregated strongly with receptor-bearing streptococci, agglutinated with sialidase-treated red blood cells, and formed monospecies biofilm. In contrast, the fimA and srtC2 mutants lacked type 2 fimbriae and were non-adherent in each of these assays. Plasmid-based expression of the deleted gene in respective mutants restored adherence to wild-type levels. These findings uncover the importance of the lectin-like activity of the polymeric FimA shaft rather than the tip. The multivalent adhesive function of FimA makes it an ideal molecule for exploring novel intervention strategies to control plaque biofilm formation.
Collapse
Affiliation(s)
- Arunima Mishra
- Department of Microbiology & Molecular Genetics, University of Texas Health Science Center, Houston, TX, USAOral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USADepartment of Molecular, Microbial & Structural Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Chenggang Wu
- Department of Microbiology & Molecular Genetics, University of Texas Health Science Center, Houston, TX, USAOral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USADepartment of Molecular, Microbial & Structural Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Jinghua Yang
- Department of Microbiology & Molecular Genetics, University of Texas Health Science Center, Houston, TX, USAOral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USADepartment of Molecular, Microbial & Structural Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - John O Cisar
- Department of Microbiology & Molecular Genetics, University of Texas Health Science Center, Houston, TX, USAOral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USADepartment of Molecular, Microbial & Structural Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Asis Das
- Department of Microbiology & Molecular Genetics, University of Texas Health Science Center, Houston, TX, USAOral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USADepartment of Molecular, Microbial & Structural Biology, University of Connecticut Health Center, Farmington, CT, USA
| | - Hung Ton-That
- Department of Microbiology & Molecular Genetics, University of Texas Health Science Center, Houston, TX, USAOral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USADepartment of Molecular, Microbial & Structural Biology, University of Connecticut Health Center, Farmington, CT, USA
| |
Collapse
|
18
|
Hendrickx APA, Bonten MJM, van Luit-Asbroek M, Schapendonk CME, Kragten AHM, Willems RJL. Expression of two distinct types of pili by a hospital-acquired Enterococcus faecium isolate. MICROBIOLOGY-SGM 2008; 154:3212-3223. [PMID: 18832326 DOI: 10.1099/mic.0.2008/020891-0] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Surface filamentous structures designated pili, and implicated in virulence, have been found on the surfaces of several Gram-positive pathogens. This work describes the conditional expression of two phenotypically distinct pilus-like structures, designated PilA and PilB, on the surface of a hospital-adapted Enterococcus faecium bloodstream isolate. E. faecium is an emerging Gram-positive opportunistic pathogen that can cause severe disease, particularly in immunocompromised patients. Expression of PilA- and PilB-type pili was analysed during different phases of growth in broth culture. During growth, PilA and PilB pilin subunits were expressed around the cross-wall in early-exponential-phase cells. Polymerization and migration of short PilB-type pili towards the poles occurred in cells from the exponential phase and long polymerized pili were expressed at the poles of cells grown to stationary phase. In contrast, PilA-type pili were not expressed in broth culture, but only when cells were grown on solid media. Furthermore, surface expression of the PilA- and PilB-type pili was regulated in a temperature-dependent manner, as polymerization of two distinct types of pili at the surface only occurred when cells were grown at 37 degrees C; no pili were observed on cells grown at 21 degrees C. Hospital-aquired E. faecium isolates were specifically enriched in pilin gene clusters, suggesting that conditional expression of pili may contribute to E. faecium pathogenesis.
Collapse
Affiliation(s)
- Antoni P A Hendrickx
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| | - Marc J M Bonten
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands.,Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| | - Miranda van Luit-Asbroek
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| | - Claudia M E Schapendonk
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| | - Angela H M Kragten
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| | - Rob J L Willems
- Department of Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, Rm G04.614, 3584 CX, Utrecht, The Netherlands
| |
Collapse
|
19
|
Fälker S, Nelson AL, Morfeldt E, Jonas K, Hultenby K, Ries J, Melefors O, Normark S, Henriques-Normark B. Sortase-mediated assembly and surface topology of adhesive pneumococcal pili. Mol Microbiol 2008; 70:595-607. [PMID: 18761697 PMCID: PMC2680257 DOI: 10.1111/j.1365-2958.2008.06396.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The rlrA genetic islet encodes an extracellular pilus in the Gram-positive pathogen Streptococcus pneumoniae. Of the three genes for structural subunits, rrgB encodes the major pilin, while rrgA and rrgC encode ancillary pilin subunits decorating the pilus shaft and tip. Deletion of all three pilus-associated sortase genes, srtB, srtC and srtD, completely prevents pilus biogenesis. Expression of srtB alone is sufficient to covalently associate RrgB subunits to one another as well as linking the RrgA adhesin and the RrgC subunit into the polymer. The active-site cysteine residue of SrtB (Cys 177) is crucial for incorporating RrgC, even when the two other sortase genes are expressed. SrtC is redundant to SrtB in permitting RrgB polymerization, and in linking RrgA to the RrgB filament, but SrtC is insufficient to incorporate RrgC. In contrast, expression of srtD alone fails to mediate RrgB polymerization, and a srtD mutant assembles heterotrimeric pilus indistinguishable from wild type. Topological studies demonstrate that pilus antigens are localized to symmetric foci at the cell surface in the presence of all three sortases. This symmetric focal presentation is abrogated in the absence of either srtB or srtD, while deletion of srtC had no effect. In addition, strains expressing srtB alone or srtC alone also displayed disrupted antigen localization, despite polymerizing subunits. Our data suggest that both SrtB and SrtC act as pilus subunit polymerases, with SrtB processing all three pilus subunit proteins, while SrtC only RrgB and RrgA. In contrast, SrtD does not act as a pilus subunit polymerase, but instead is required for wild-type focal presentation of the pilus at the cell surface.
Collapse
Affiliation(s)
- Stefan Fälker
- Department of Bacteriology, Swedish Institute for Infectious Disease Control, SE-171 82 Solna, Sweden
| | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Budzik JM, Marraffini LA, Schneewind O. Assembly of pili on the surface of Bacillus cereus vegetative cells. Mol Microbiol 2008; 66:495-510. [PMID: 17897374 DOI: 10.1111/j.1365-2958.2007.05939.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Vegetative forms of Bacillus cereus are reported to form pili, thin protein filaments that protrude up to 1 mum from the bacterial surface. Pili are assembled from two precursor proteins, BcpA and BcpB, in a manner requiring a pilus-associated sortase enzyme (SrtD). Pili are also formed on the surface of Bacillus anthracis expressing bcpA-srtD-bcpB. BcpA is distributed throughout the entire pilus, whereas BcpB appears positioned at its tip. In agreement with the hypothesis for pilus assembly in Gram-positive bacteria, BcpA encompasses the YPK pilin motif and the LPXTG sorting signal, each of which is absolutely required for the incorporation of BcpA and BcpB into pili. In contrast to BcpB, which relies on the presence of BcpA for incorporation into pili, BcpA fibre assembly occurs even in the absence of BcpB. B. anthracis sortase A (srtA), but not sortase B (srtB) or C (srtC), is required for proper anchoring of pili to the bacterial envelope, suggesting that BcpA/BcpB pili are linked to peptidoglycan cross-bridges.
Collapse
Affiliation(s)
- Jonathan M Budzik
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA
| | | | | |
Collapse
|
21
|
Mandlik A, Swierczynski A, Das A, Ton-That H. Pili in Gram-positive bacteria: assembly, involvement in colonization and biofilm development. Trends Microbiol 2008; 16:33-40. [PMID: 18083568 DOI: 10.1016/j.tim.2007.10.010] [Citation(s) in RCA: 301] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 10/29/2007] [Accepted: 10/29/2007] [Indexed: 02/03/2023]
Abstract
Various cell-surface multisubunit protein polymers, known as pili or fimbriae, have a pivotal role in the colonization of specific host tissues by many pathogenic bacteria. In contrast to Gram-negative bacteria, Gram-positive bacteria assemble pili by a distinct mechanism involving a transpeptidase called sortase. Sortase crosslinks individual pilin monomers and ultimately joins the resulting covalent polymer to the cell-wall peptidoglycan. Here we review current knowledge of this mechanism and the roles of Gram-positive pili in the colonization of specific host tissues, modulation of host immune responses and the development of bacterial biofilms.
Collapse
Affiliation(s)
- Anjali Mandlik
- Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030, USA
| | | | | | | |
Collapse
|
22
|
Maegawa T, Nishitani Y, Osawa R. Polymorphism of Genes Associated with Putative Fimbriae of <i>Bifidobacterium longum</i> Strains, with Specific Reference to Their Host Specific Colonization. Biosci Microflora 2008. [DOI: 10.12938/bifidus.27.49] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Takahiro Maegawa
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University
| | - Yosuke Nishitani
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University
| | - Ro Osawa
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University
| |
Collapse
|
23
|
Mandlik A, Swierczynski A, Das A, Ton-That H. Corynebacterium diphtheriae employs specific minor pilins to target human pharyngeal epithelial cells. Mol Microbiol 2007; 64:111-24. [PMID: 17376076 PMCID: PMC2844904 DOI: 10.1111/j.1365-2958.2007.05630.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Adherence to host tissues mediated by pili is pivotal in the establishment of infection by many bacterial pathogens. Corynebacterium diphtheriae assembles on its surface three distinct pilus structures. The function and the mechanism of how various pili mediate adherence, however, have remained poorly understood. Here we show that the SpaA-type pilus is sufficient for the specific adherence of corynebacteria to human pharyngeal epithelial cells. The deletion of the spaA gene, which encodes the major pilin forming the pilus shaft, abolishes pilus assembly but not adherence to pharyngeal cells. In contrast, adherence is greatly diminished when either minor pilin SpaB or SpaC is absent. Antibodies directed against either SpaB or SpaC block bacterial adherence. Consistent with a direct role of the minor pilins, latex beads coated with SpaB or SpaC protein bind specifically to pharyngeal cells. Therefore, tissue tropism of corynebacteria for pharyngeal cells is governed by specific minor pilins. Importantly, immunoelectron microscopy and immunofluorescence studies reveal clusters of minor pilins that are anchored to cell surface in the absence of a pilus shaft. Thus, the minor pilins may also be cell wall anchored in addition to their incorporation into pilus structures that could facilitate tight binding to host cells during bacterial infection.
Collapse
Affiliation(s)
| | | | | | - Hung Ton-That
- For correspondence. ; Tel. (+1) 860 679 8452; Fax (+1) 860 679 3408
| |
Collapse
|
24
|
Chen P, Cisar JO, Hess S, Ho JTC, Leung KP. Amended description of the genes for synthesis of Actinomyces naeslundii T14V type 1 fimbriae and associated adhesin. Infect Immun 2007; 75:4181-5. [PMID: 17485454 PMCID: PMC1952015 DOI: 10.1128/iai.01955-06] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type 1 fimbriae of Actinomyces naeslundii T14V mediate adhesion of this gram-positive species to the tooth surface. The present findings show that the locus for type 1 fimbria production in this strain includes three genes, fimQ for a minor fimbrial subunit that appears to be an adhesin, fimP for the major structural subunit, and srtC1 for a type 1 fimbria-specific sortase involved in the assembly of these structures.
Collapse
Affiliation(s)
- Ping Chen
- Microbiology Branch, U.S. Army Dental and Trauma Research Detachment, 310B B Street, Great Lakes, IL 60088, USA
| | | | | | | | | |
Collapse
|
25
|
Mishra A, Das A, Cisar JO, Ton-That H. Sortase-catalyzed assembly of distinct heteromeric fimbriae in Actinomyces naeslundii. J Bacteriol 2007; 189:3156-65. [PMID: 17277070 PMCID: PMC1855841 DOI: 10.1128/jb.01952-06] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two types of adhesive fimbriae are expressed by Actinomyces; however, the architecture and the mechanism of assembly of these structures remain poorly understood. In this study we characterized two fimbrial gene clusters present in the genome of Actinomyces naeslundii strain MG-1. By using immunoelectron microscopy and biochemical analysis, we showed that the fimQ-fimP-srtC1-fimR gene cluster encodes a fimbrial structure (designated type 1) that contains a major subunit, FimP, forming the shaft and a minor subunit, FimQ, located primarily at the tip. Similarly, the fimB-fimA-srtC2 gene cluster encodes a distinct fimbrial structure (designated type 2) composed of a shaft protein, FimA, and a tip protein, FimB. By using allelic exchange, we constructed an in-frame deletion mutant that lacks the SrtC2 sortase. This mutant produces abundant type 1 fimbriae and expresses the monomeric FimA and FimB proteins, but it does not assemble type 2 fimbriae. Thus, SrtC2 is a fimbria-specific sortase that is essential for assembly of the type 2 fimbriae. Together, our experiments pave the way for several lines of molecular investigation that are necessary to elucidate the fimbrial assembly pathways in Actinomyces and their function in the pathogenesis of different biofilm-related oral diseases.
Collapse
Affiliation(s)
- Arunima Mishra
- Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030, USA
| | | | | | | |
Collapse
|
26
|
Abstract
Enterococcus faecalis is an important agent of endocarditis and urinary tract infections, which occur frequently in hospitals. Antimicrobial therapy is complicated by the emergence of drug-resistant strains, which contribute significantly to mortality associated with E. faecalis infection. In this issue of the JCI, Nallapareddy and colleagues report that E. faecalis produces pili on its surface and that these proteinaceous fibers are used for bacterial adherence to host tissues and for the establishment of biofilms and endocarditis (see the related article beginning on page 2799). This information may enable new vaccine strategies for the prevention of E. faecalis infections.
Collapse
Affiliation(s)
- Jonathan M Budzik
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | | |
Collapse
|
27
|
Abstract
Surface proteins are critical in determining the identifying characteristics of individual bacteria and their interaction with the environment. Because the structure of the cell surface is the major characteristic that distinguishes gram-positive from gram-negative bacteria, the processes used to transport and attach these proteins show significant differences between these bacterial classes. This review is intended to highlight these differences and to focus attention on areas that are ripe for further investigation.
Collapse
Affiliation(s)
- June R Scott
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
| | | |
Collapse
|
28
|
Abstract
Bacteria attach to their appropriate environmental niche by using adhesins. To maximize their contact with the environment, adhesins are often present on the ends of long hairlike structures called pili. Recently, attention has focused on pili of Gram-positive bacteria because they may be vaccine candidates in important human pathogens. These pili differ from the well-studied pili of Gram-negative bacteria because their subunits are covalently linked, they do not require specific chaperones for assembly, and the tip protein (likely to be the adhesin) is not required to initiate formation of the pilus structure. In Gram-positive bacteria, the genes for pili occur in clusters, which may constitute mobile genetic elements. These clusters include the transpeptidase(s) of the sortase family that is/are required for polymerization of the subunit proteins. However, efficient covalent attachment of the completed pilus structure to the cell wall is accomplished, in cases where this has been studied, by the 'housekeeping' sortase, which is responsible for attachment to the peptidoglycan of most surface proteins containing cell wall sorting signals. This enzyme is encoded elsewhere on the genome. Because pili of Gram-positive bacteria have not been extensively investigated yet, we hope that this MicroReview will help to pinpoint the areas most in need of further study.
Collapse
Affiliation(s)
- June R Scott
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA.
| | | |
Collapse
|
29
|
Telford JL, Barocchi MA, Margarit I, Rappuoli R, Grandi G. Pili in Gram-positive pathogens. Nat Rev Microbiol 2006; 4:509-19. [PMID: 16778837 DOI: 10.1038/nrmicro1443] [Citation(s) in RCA: 331] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Most bacterial pathogens have long filamentous structures known as pili or fimbriae extending from their surface. These structures are often involved in the initial adhesion of the bacteria to host tissues during colonization. In gram-negative bacteria, pili are typically formed by non-covalent interactions between pilin subunits. By contrast, the recently discovered pili in gram-positive pathogens are formed by covalent polymerization of adhesive pilin subunits. Evidence from studies of pili in the three principal streptococcal pathogens of humans indicates that the genes that encode the pilin subunits and the enzymes that are required for the assembly of these subunits into pili have been acquired en bloc by the horizontal transfer of a pathogenicity island.
Collapse
Affiliation(s)
- John L Telford
- Novartis Vaccines & Diagnostics Srl, Via Fiorentina 1, 53100 Siena, Italy.
| | | | | | | | | |
Collapse
|
30
|
Marraffini LA, Dedent AC, Schneewind O. Sortases and the art of anchoring proteins to the envelopes of gram-positive bacteria. Microbiol Mol Biol Rev 2006; 70:192-221. [PMID: 16524923 PMCID: PMC1393253 DOI: 10.1128/mmbr.70.1.192-221.2006] [Citation(s) in RCA: 498] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The cell wall envelopes of gram-positive bacteria represent a surface organelle that not only functions as a cytoskeletal element but also promotes interactions between bacteria and their environment. Cell wall peptidoglycan is covalently and noncovalently decorated with teichoic acids, polysaccharides, and proteins. The sum of these molecular decorations provides bacterial envelopes with species- and strain-specific properties that are ultimately responsible for bacterial virulence, interactions with host immune systems, and the development of disease symptoms or successful outcomes of infections. Surface proteins typically carry two topogenic sequences, i.e., N-terminal signal peptides and C-terminal sorting signals. Sortases catalyze a transpeptidation reaction by first cleaving a surface protein substrate at the cell wall sorting signal. The resulting acyl enzyme intermediates between sortases and their substrates are then resolved by the nucleophilic attack of amino groups, typically provided by the cell wall cross bridges of peptidoglycan precursors. The surface protein linked to peptidoglycan is then incorporated into the envelope and displayed on the microbial surface. This review focuses on the mechanisms of surface protein anchoring to the cell wall envelope by sortases and the role that these enzymes play in bacterial physiology and pathogenesis.
Collapse
Affiliation(s)
- Luciano A Marraffini
- Department of Microbiology, Genetics and Cell Biology, University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA
| | | | | |
Collapse
|
31
|
Gaspar AH, Ton-That H. Assembly of distinct pilus structures on the surface of Corynebacterium diphtheriae. J Bacteriol 2006; 188:1526-33. [PMID: 16452436 PMCID: PMC1367254 DOI: 10.1128/jb.188.4.1526-1533.2006] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Accepted: 12/01/2005] [Indexed: 02/07/2023] Open
Abstract
Different surface organelles contribute to specific interactions of a pathogen with host tissues or infectious partners. Multiple pilus gene clusters potentially encoding different surface structures have been identified in several gram-positive bacterial genomes sequenced to date, including actinomycetales, clostridia, corynebacteria, and streptococci. Corynebacterium diphtheriae has been shown to assemble a pilus structure, with sortase SrtA essential for the assembly of a major subunit SpaA and two minor proteins, SpaB and SpaC. We report here the characterization of a second pilus consisting of SpaD, SpaE, and SpaF, of which SpaD and SpaE form the pilus shaft and SpaF may be located at the pilus tip. The structure of the SpaDEF pilus contains no SpaABC pilins as detected by immunoelectron microscopy. Neither deletion of spaA nor sortase srtA abolishes SpaDEF pilus formation. The assembly of the SpaDEF pilus requires specific sortases located within the SpaDEF pilus gene cluster. Although either sortase SrtB or SrtC is sufficient to polymerize SpaDF, the incorporation of SpaE into the SpaD pili requires sortase SrtB. In addition, an alanine in place of the lysine of the SpaD pilin motif abrogates pilus polymerization. Thus, SpaD, SpaE, and SpaF constitute a different pilus structure that is independently assembled and morphologically distinct from the SpaABC pili and possibly other pili of C. diphtheriae.
Collapse
Affiliation(s)
- Andrew H Gaspar
- Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, 263 Farmington Ave., Farmington, Connecticut 06030, USA
| | | |
Collapse
|
32
|
Jost BH, Billington SJ. Arcanobacterium pyogenes: molecular pathogenesis of an animal opportunist. Antonie van Leeuwenhoek 2005; 88:87-102. [PMID: 16096685 DOI: 10.1007/s10482-005-2316-5] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2004] [Accepted: 02/15/2005] [Indexed: 10/25/2022]
Abstract
Arcanobacterium pyogenes is a commensal and an opportunistic pathogen of economically important livestock, causing diseases as diverse as mastitis, liver abscessation and pneumonia. This organism possesses a number of virulence factors that contribute to its pathogenic potential. A. pyogenes expresses a cholesterol-dependent cytolysin, pyolysin, which is a haemolysin and is cytolytic for immune cells, including macrophages. Expression of pyolysin is required for virulence and this molecule is the most promising vaccine candidate identified to date. A. pyogenes also possesses a number of adherence mechanisms, including two neuraminidases, the action of which are required for full adhesion to epithelial cells, and several extracellular matrix-binding proteins, including a collagen-binding protein, which may be required for adhesion to collagen-rich tissue. A. pyogenes also expresses fimbriae, which are similar to the type 2 fimbriae of Actinomyces naeslundii, and forms biofilms. However, the role of these factors in the pathogenesis of A. pyogenes infections remains to be elucidated. A. pyogenes also invades and survives within epithelial cells and can survive within J774A.1 macrophages for up to 72 h, suggesting an important role for A. pyogenes interaction with host cells during pathogenesis. The two component regulatory system, PloSR, up-regulates pyolysin expression and biofilm formation but down-regulates expression of proteases, suggesting that it may act as a global regulator of A. pyogenes virulence. A. pyogenes is a versatile pathogen, with an arsenal of virulence determinants. However, most aspects of the pathogenesis of infection caused by this important opportunistic pathogen remain poorly characterized.
Collapse
Affiliation(s)
- B Helen Jost
- Department of Veterinary Science and Microbiology, University of Arizona, 1117 East Lowell Street, Tucson, AZ 85721, USA.
| | | |
Collapse
|
33
|
|
34
|
Dramsi S, Trieu-Cuot P, Bierne H. Sorting sortases: a nomenclature proposal for the various sortases of Gram-positive bacteria. Res Microbiol 2005; 156:289-97. [PMID: 15808931 DOI: 10.1016/j.resmic.2004.10.011] [Citation(s) in RCA: 168] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2004] [Accepted: 10/08/2004] [Indexed: 11/21/2022]
Abstract
Bacterial surface proteins constitute a diverse group of molecules with important functions, such as adherence, invasion, signaling and interaction with the host immune system or the environment. In Gram-positive bacteria, many surface proteins are anchored to the cell wall envelope by an enzyme named sortase, which recognizes a conserved carboxylic sorting motif. The sequence of the prototype staphylococcal SrtA has been widely used to identify homologs in bacterial genomes, revealing a profusion of sortases in almost all Gram-positive bacteria, often with more than one sortase-like protein per genome [M.J. Pallen, A.C. Lam, M. Antonio, K. Dunbar, Trends Microbiol. 9 (2001) 97-102]. In light of increasing reports on the identification and/or characterization of paralogous sortase genes, a classification of sortases now appears necessary. This report provides an analysis of sixty-one sortases from complete Gram-positive genomes, and suggests the existence of four structural groups of sortases. We propose the classification of sortases into 4 classes designated A, B, C and D. This classification should help to discriminate between sortases in the future.
Collapse
Affiliation(s)
- Shaynoor Dramsi
- Unité de Biologie des Bactéries Pathogènes à Gram-positif, URA CNRS 2172, 25, rue du Dr. Roux, 75724 Paris, France.
| | | | | |
Collapse
|
35
|
Abstract
Surface proteins of Gram-positive pathogens play various key roles in pathogenicity. Therefore, these proteins are of great interest in terms of understanding the infection process and have potential as targets for therapy. A major mechanism for the surface display of proteins by Gram-positive bacteria is sortase-mediated covalent attachment to the cell wall. The importance of sortase enzymes in the virulence of several pathogens is now becoming apparent, as are some of the more detailed workings of the enzyme and anchoring pathway. These recent advances are discussed.
Collapse
Affiliation(s)
- Gavin K Paterson
- Division of Infection and Immunity, The Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, Scotland, UK G12 8QQ
| | | |
Collapse
|
36
|
Affiliation(s)
- Hung Ton-That
- Committee on Microbiology, University of Chicago, 920 East 58th Street, Chicago, Illinois 60637, USA
| | | |
Collapse
|
37
|
Lévesque C, Vadeboncoeur C, Frenette M. The csp operon of Streptococcus salivarius encodes two predicted cell-surface proteins, one of which, CspB, is associated with the fimbriae. MICROBIOLOGY-SGM 2004; 150:189-198. [PMID: 14702412 DOI: 10.1099/mic.0.26592-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A Tn917 mutant library was generated to identify genes involved in the biogenesis of Streptococcus salivarius fimbriae. A fimbria-deficient mutant was isolated by negative selection using an immunomagnetic separation technique with specific anti-fimbriae polyclonal antibodies (pAbs). The transposon was inserted in an ORF, called orf176, which encoded a protein of unknown function. The transposon prevented the transcription of orf176 as well as two genes located downstream, which are designated cspA and cspB and which form the csp operon. Sequence analyses of CspA and CspB revealed that both proteins possessed the classic cell-wall-anchoring motif (LPXTG) of Gram-positive bacterial surface proteins. Recombinant CspA (rCspA) and CspB (rCspB) proteins were generated in Escherichia coli and used to produce pAbs. Immunolocalization experiments showed that anti-rCspB, but not anti-rCspA antibodies specifically recognized S. salivarius fimbriae. Our results suggested that the csp operon encoded predicted cell-surface proteins, one of which, CspB, was associated with the fimbriae.
Collapse
Affiliation(s)
- Céline Lévesque
- Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire and Département de Biochimie et de Microbiologie, Université Laval, Québec, Canada G1K 7P4
| | - Christian Vadeboncoeur
- Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire and Département de Biochimie et de Microbiologie, Université Laval, Québec, Canada G1K 7P4
| | - Michel Frenette
- Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire and Département de Biochimie et de Microbiologie, Université Laval, Québec, Canada G1K 7P4
| |
Collapse
|
38
|
Lee SG, Pancholi V, Fischetti VA. Characterization of a unique glycosylated anchor endopeptidase that cleaves the LPXTG sequence motif of cell surface proteins of Gram-positive bacteria. J Biol Chem 2002; 277:46912-22. [PMID: 12370182 DOI: 10.1074/jbc.m208660200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The precursors of most surface proteins on Gram-positive bacteria have a C-terminal hydrophobic domain and charged tail, preceded by a conserved LPXTG motif that signals the anchoring process. This motif is the substrate for an enzyme, termed sortase, which has transpeptidation activity resulting in the cleavage of the LPXTG sequence and ultimate attachment of the protein to the peptidoglycan. While screening a group A streptococcal membrane extract for cleavage activity of the LPXTG motif, we identified an enzyme (which we term "LPXTGase") that differs significantly from sortase but also cleaves this motif. The enzyme is heavily glycosylated, which is required for its activity. Amino acid composition and sequence analysis revealed that LPXTGase differs from other enzymes, in that the molecule, which is about 14 kDa in size, has no aromatic amino acids, is rich in alanine, and is 30% composed of uncommon amino acids, suggesting a nonribosomal construction. A similar enzyme found in the membrane extract of Staphylococcus aureus, indicates that this unusual molecule may be common among Gram-positive bacteria. Whereas peptide antibiotics have been reported from bacillus species that also contain unusual amino acids and are synthesized non-ribosomally on amino acid-activating polyenzyme templates, this would be the first reported enzyme that may be similarly synthesized.
Collapse
Affiliation(s)
- Sung G Lee
- Laboratory of Bacterial Pathogenesis Rockefeller University, New York, New York 10021, USA
| | | | | |
Collapse
|
39
|
Schell MA, Karmirantzou M, Snel B, Vilanova D, Berger B, Pessi G, Zwahlen MC, Desiere F, Bork P, Delley M, Pridmore RD, Arigoni F. The genome sequence of Bifidobacterium longum reflects its adaptation to the human gastrointestinal tract. Proc Natl Acad Sci U S A 2002; 99:14422-7. [PMID: 12381787 PMCID: PMC137899 DOI: 10.1073/pnas.212527599] [Citation(s) in RCA: 666] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Bifidobacteria are Gram-positive prokaryotes that naturally colonize the human gastrointestinal tract (GIT) and vagina. Although not numerically dominant in the complex intestinal microflora, they are considered as key commensals that promote a healthy GIT. We determined the 2.26-Mb genome sequence of an infant-derived strain of Bifidobacterium longum, and identified 1,730 possible coding sequences organized in a 60%-GC circular chromosome. Bioinformatic analysis revealed several physiological traits that could partially explain the successful adaptation of this bacteria to the colon. An unexpectedly large number of the predicted proteins appeared to be specialized for catabolism of a variety of oligosaccharides, some possibly released by rare or novel glycosyl hydrolases acting on "nondigestible" plant polymers or host-derived glycoproteins and glycoconjugates. This ability to scavenge from a large variety of nutrients likely contributes to the competitiveness and persistence of bifidobacteria in the colon. Many genes for oligosaccharide metabolism were found in self-regulated modules that appear to have arisen in part from gene duplication or horizontal acquisition. Complete pathways for all amino acids, nucleotides, and some key vitamins were identified; however, routes for Asp and Cys were atypical. More importantly, genome analysis provided insights into the reciprocal interactions of bifidobacteria with their hosts. We identified polypeptides that showed homology to most major proteins needed for production of glycoprotein-binding fimbriae, structures that could possibly be important for adhesion and persistence in the GIT. We also found a eukaryotic-type serine protease inhibitor (serpin) possibly involved in the reported immunomodulatory activity of bifidobacteria.
Collapse
Affiliation(s)
- Mark A Schell
- Nestlé Research Center, Vers-Chez-les-Blanc, Lausanne 1000, Switzerland
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Li T, Khah MK, Slavnic S, Johansson I, Strömberg N. Different type 1 fimbrial genes and tropisms of commensal and potentially pathogenic Actinomyces spp. with different salivary acidic proline-rich protein and statherin ligand specificities. Infect Immun 2001; 69:7224-33. [PMID: 11705891 PMCID: PMC98805 DOI: 10.1128/iai.69.12.7224-7233.2001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Actinomyces spp. exhibit type 1 fimbria-mediated adhesion to salivary acidic proline-rich proteins (PRPs) and statherin ligands. Actinomyces spp. with different animal and tissue origins belong to three major adhesion types as relates to ligand specificity and type 1 fimbria genes. (i) In preferential acidic-PRP binding, strains of Actinomyces naeslundii genospecies 1 and 2 from human and monkey mouths displayed at least three ligand specificities characterized by preferential acidic-PRP binding. Slot blot DNA hybridization showed seven highly conserved type 1 fimbria genes (orf1- to -6 and fimP) in genospecies 1 and 2 strains, except that orf5 and orf3 were divergent in genospecies 1. (ii) In preferential statherin binding, oral Actinomyces viscosus strains of rat and hamster origin (and strain 19246 from a human case of actinomycosis) bound statherin preferentially. DNA hybridization and characterization of the type 1 fimbria genes from strain 19246 revealed a homologous gene cluster of four open reading frames (orfA to -C and fimP). Bioinformatics suggested sortase (orfB, orf4, and part of orf5), prepilin peptidase (orfC and orf6), fimbria subunit (fimP), and usher- and autotransporter-like (orfA and orf1 to -3) functions. Those gene regions corresponding to orf3 and orf5 were divergent, those corresponding to orf2, orf1, and fimP were moderately conserved, and those corresponding to orf4 and orf6 were highly conserved. Restriction fragment length polymorphism analyses using a fimP probe separated human and monkey and rat and hamster strains into phylogenetically different groups. (iii) In statherin-specific binding, strains of A. naeslundii genospecies 1 from septic and other human infections displayed a low-avidity binding to statherin. Only the orf4 and orf6 gene regions were highly conserved. Finally, rat saliva devoid of statherin bound bacterial strains avidly irrespective of ligand specificity, and specific antisera detected either type 1, type 2, or both types of fimbria on the investigated Actinomyces strains.
Collapse
Affiliation(s)
- T Li
- Department of Odontology/Cariology, Umeå University, SE-901 87 Umeå, Sweden
| | | | | | | | | |
Collapse
|
41
|
Hoflack L, Yeung MK. Actinomyces naeslundii fimbrial protein Orf977 shows similarity to a streptococcal adhesin. ORAL MICROBIOLOGY AND IMMUNOLOGY 2001; 16:319-20. [PMID: 11555311 DOI: 10.1034/j.1399-302x.2001.016005319.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The nucleotide sequence of the chromosomal DNA, upstream of Actinomyces naeslundii T14V fimbrial gene fimA, was determined. One open reading frame (orf977) encoding 977 amino acids was found, preceded by a gene homologous to elongation factor TU. Database searches revealed that Orf977 was homologous to CshA, a Streptococcus gordonii protein involved in cell adhesion. Previous studies had already determined two genes in the type 2 fimbrial gene cluster of A. naeslundii T14V: the structural subunit fimA, and orf365 with unknown function, followed by ribosomal genes. This study completes the type 2 fimbrial gene cluster sequence.
Collapse
Affiliation(s)
- L Hoflack
- Department of Pediatric Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | | |
Collapse
|
42
|
Wu H, Fives-Taylor PM. Molecular strategies for fimbrial expression and assembly. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 2001; 12:101-15. [PMID: 11345521 DOI: 10.1177/10454411010120020101] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Fimbriae or pili are long, filamentous, multimeric macromolecules found on the bacterial cell surface. Bacteria express a diverse array of fimbriae or pili that are involved in bacterial adherence and invasion. Fimbriae can be categorized based on their modes of expression and assembly. Type I fimbriae and P pili are distributed peritrichously and translocated to the cell surface by a chaperone/usher pathway. Type 4 pili are located at the pole of the cell and assembled via the type II secretion system. Curli fimbriae are coiled surface structures assembled by an extracellular nucleation/precipitation pathway. Fimbriae of oral gram-negative and gram-positive bacteria have not been well-studied as compared with the fimbriae of enteric pathogens. Oral pathogens, such as Eikenella corrodens, Actinobacillus actinomycetemcomitans, and Porphyromonas gingivalis, possess fimbriae that have been implicated in bacterial adhesion and invasion. These fimbriae are potential virulence factors in oral infectious processes. A. actinomycetemcomitans and E. corrodens have Type 4-like fimbriae, whereas P. gingivalis displays a unique type of fimbriae. To date, fimbriae of the oral primary colonizers, Actinomyces naeslundii and Streptococcus parasanguis, represent the only fimbriae characterized for any gram-positive bacteria. The putative major fimbrial subunits, FimA and FimP of A. naeslundii and Fap1 of S. parasanguis, contain a signal sequence and cell-wall-sorting signal. The presence of extensive dipeptide repeats in Fap1 makes it unique among fimbrial molecules. Based on experimental data, a nucleation/precipitation pathway is proposed for fimbrial biogenesis of both S. parasanguis and A. naeslundii, although we cannot rule out an alternative covalent linkage model. The model systems described in this review served as a framework for hypotheses for how the known molecular factors of fimbriae on oral bacteria may be expressed and assembled.
Collapse
Affiliation(s)
- H Wu
- Department of Medicine, University of Vermont, Burlington 05405, USA
| | | |
Collapse
|
43
|
Bergeron LJ, Burne RA. Roles of fructosyltransferase and levanase-sucrase of Actinomyces naeslundii in fructan and sucrose metabolism. Infect Immun 2001; 69:5395-402. [PMID: 11500409 PMCID: PMC98649 DOI: 10.1128/iai.69.9.5395-5402.2001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2001] [Accepted: 05/23/2001] [Indexed: 11/20/2022] Open
Abstract
The ability of Actinomyces naeslundii to convert sucrose to extracellular homopolymers of fructose and to catabolize these types of polymers is suspected to be a virulence trait that contributes to the initiation and progression of dental caries and periodontal diseases. Previously, we reported on the isolation and characterization of the gene, ftf, encoding the fructosyltransferase (FTF) of A. naeslundii WVU45. Allelic exchange mutagenesis was used to inactivate ftf, revealing that FTF-deficient stains were completely devoid of the capacity to produce levan-type (beta2,6-linked) polysaccharides. A polyclonal antibody was raised to a histidine-tagged, purified A. naeslundii FTF, and the antibody was used to localize the enzyme in the supernatant fluid. A sensitive technique was developed to detect levan formation by proteins that had been separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the method was used to confirm that the levan-synthesizing activity of A. naeslundii existed predominantly in a cell-free form, that a small amount of the activity was cell associated, and that the ftf mutant was unable to produce levans. By using the nucleotide sequence of the levanase gene of a genospecies 2 A. naeslundii, formerly Actinomyces viscosus, a portion of a homologue of this gene (levJ) was amplified by PCR and inserted into a suicide vector, and the resulting construct was used to inactivate the levJ gene in the genospecies 1 strain WVU45. A variety of physiologic and biochemical studies were performed on the wild-type and LevJ-deficient strains to demonstrate that (i) this enzyme was the dominant levanase and sucrase of A. naeslundii; (ii) that LevJ was inducible by growth in sucrose; (iii) that the LevJ activity was found predominantly (>90%) in a cell-associated form; and (iv) that there was a second, fructose-inducible fructan hydrolase activity produced by these strains. The data provide the first detailed molecular analysis of fructan production and catabolism in this abundant and important oral bacterium.
Collapse
Affiliation(s)
- L J Bergeron
- Center for Oral Biology and Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | | |
Collapse
|
44
|
Abstract
A range of surface proteins is anchored to the cell walls of Gram-positive pathogens such as Staphylococcus aureus by the transpeptidase sortase. Until now, sortase-like proteins and their substrates appeared to be limited mainly to such pathogens. However, by searching for sortase homologues among complete and incomplete genome sequences, we have found them to be present in almost all Gram-positives, a single Gram-negative bacterium and an archaean. There is usually more than one sortase-like protein encoded in each Gram-positive genome, and the genes encoding the sortase-like proteins are often clustered with genes encoding their likely substrates.
Collapse
Affiliation(s)
- M J Pallen
- Department of Microbiology and Immunobiology, Queen's University Belfast, Belfast, UK BT12 6BN.
| | | | | | | |
Collapse
|
45
|
Abstract
Oral microbial-plaque communities are biofilms composed of numerous genetically distinct types of bacteria that live in close juxtaposition on host surfaces. These bacteria communicate through physical interactions called coaggregation and coadhesion, as well as other physiological and metabolic interactions. Streptococci and actinomyces are the major initial colonizers of the tooth surface, and the interactions between them and their substrata help establish the early biofilm community. Fusobacteria play a central role as physical bridges that mediate coaggregation of cells and as physiological bridges that promote anaerobic microenvironments which protect coaggregating strict anaerobes in an aerobic atmosphere. New technologies for investigating bacterial populations with 16S rDNA probes have uncovered previously uncultured bacteria and have offered an approach to in situ examination of the spatial arrangement of the participant cells in oral-plaque biofilms. Flow cells with saliva-coated surfaces are particularly useful for studies of biofilm formation and observation. The predicted sequential nature of colonization of the tooth surface by members of different genera can be investigated by using these new technologies and imaging the cells in situ with confocal scanning laser microscopy. Members of at least seven genera now can be subjected to genetic studies owing to the discovery of gene-transfer systems in these genera. Identification of contact-inducible genes in streptococci offers an avenue to explore bacterial responses to their environment and leads the way toward understanding communication among inhabitants of a multispecies biofilm.
Collapse
Affiliation(s)
- P E Kolenbrander
- Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA.
| |
Collapse
|
46
|
Mazmanian SK, Liu G, Jensen ER, Lenoy E, Schneewind O. Staphylococcus aureus sortase mutants defective in the display of surface proteins and in the pathogenesis of animal infections. Proc Natl Acad Sci U S A 2000; 97:5510-5. [PMID: 10805806 PMCID: PMC25859 DOI: 10.1073/pnas.080520697] [Citation(s) in RCA: 353] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/1999] [Indexed: 02/05/2023] Open
Abstract
Many gram-positive bacteria covalently tether their surface adhesins to the cell wall peptidoglycan. We find that surface proteins of Staphylococcus aureus are linked to the cell wall by sortase, an enzyme that cleaves polypeptides at a conserved LPXTG motif. S. aureus mutants lacking sortase fail to process and display surface proteins and are defective in the establishment of infections. Thus, the cell wall envelope of gram-positive bacteria represents a surface organelle responsible for interactions with the host environment during the pathogenesis of bacterial infections.
Collapse
Affiliation(s)
- S K Mazmanian
- Department of Microbiology and Immunology, University of California, Los Angeles, School of Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA
| | | | | | | | | |
Collapse
|
47
|
Yeung MK. Molecular and genetic analyses of Actinomyces spp. CRITICAL REVIEWS IN ORAL BIOLOGY AND MEDICINE : AN OFFICIAL PUBLICATION OF THE AMERICAN ASSOCIATION OF ORAL BIOLOGISTS 2000; 10:120-38. [PMID: 10759417 DOI: 10.1177/10454411990100020101] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Members of the genus Actinomyces are predominant primary colonizers of the oral cavity and play an important role in initiating plaque development. These bacteria have evolved unique mechanisms that favor colonization and persistence in this micro-environment. The expression of cell-surface fimbriae is correlated with the ability of these bacteria to adhere to specific receptors on the tooth and mucosal surfaces, and to interact with other plaque bacteria. The elaboration of sialidase is thought to enhance fimbriae-mediated adherence by unmasking the fimbrial receptors on mammalian cells. The presence of certain cell-associated or extracellular enzymes, including those involved in sucrose or urea metabolism, may provide the means for these bacteria to thrive under conditions when other growth nutrients are not available. Moreover, these enzyme activities may influence the distribution of other plaque bacteria and promote selection for Actinomyces spp. in certain ecological niches. The recent development of a genetic transfer system for Actinomyces spp. has allowed for studies the results of which demonstrate the existence of multiple genes involved in fimbriae synthesis and function, and facilitated the construction of allelic replacement mutants at each gene locus. Analyses of these mutants have revealed a direct correlation between the synthesis of assembled fimbriae and the observed adherence properties. Further genetic analysis of the various enzyme activities detected from strains of Actinomyces should allow for an assessment of the role of these components in microbial ecology, and their contribution to the overall success of Actinomyces spp. as a primary colonizer and a key player in oral health and disease.
Collapse
Affiliation(s)
- M K Yeung
- Department of Pediatric Dentistry, University of Texas Health Science Center at San Antonio, 78284, USA
| |
Collapse
|
48
|
Wu H, Fives-Taylor PM. Identification of dipeptide repeats and a cell wall sorting signal in the fimbriae-associated adhesin, Fap1, of Streptococcus parasanguis. Mol Microbiol 1999; 34:1070-81. [PMID: 10594831 DOI: 10.1046/j.1365-2958.1999.01670.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Fap1, a fimbriae-associated protein, is involved in fimbriae assembly and adhesion of Streptococcus parasanguis FW213 (Wu et al., 1998). In this study, the sequence of the fap1 gene was resolved using a primer island transposition system. Sequence analysis indicated that fap1 was composed of 7659 nucleotides. The predicted Fap1 protein contains an unusually long signal sequence (50 amino acid residues), a cell wall sorting signal and two repeat regions. Repeat regions I and II have a similar dipeptide composition (E/V/I)S, composed of 28 and 1000 repeats respectively. The two regions combined accounted for 80% of the Fap1 coding region. The experimental amino acid composition and isoelectric point (pI) of Fap1 were similar to that predicted from the deduced Fap1 protein. Results of Northern analyses revealed that the fap1 open reading frame (ORF) was transcribed as a 7.8 kb monocistronic message. Insertional inactivation at the 3' end, downstream of the fap1 ORF, did not affect Fap1, fimbrial expression or bacterial adhesion. Insertional inactivation of fap1 immediately upstream of the repeat region II abolished expression of Fap1 and fimbriae, and was concurrent with a diminution in adhesion of FW213. Inactivation of the cell wall sorting signal of fap1 also eliminated long fimbrial formation and reduced the ability of FW213 to bind to SHA. Fap1 was no longer anchored on the cell surface. Large quantities of truncated Fap1 were found in the growth medium instead. These results suggest that the fap1 ORF alone is sufficient to support Fap1 expression and adhesion, and demonstrate that anchorage of Fap1 on the cell surface is required for long fimbriae formation. These data further document the role of long fimbriae in adhesion of S. parasanguis FW213 to SHA.
Collapse
Affiliation(s)
- H Wu
- Room 117, Stafford Hall, Department of Microbiology and Molecular Genetics, College of Medicine and College of Agriculture and Life Sciences, University of Vermont, Burlington, VT 05405, USA
| | | |
Collapse
|
49
|
Navarre WW, Schneewind O. Surface proteins of gram-positive bacteria and mechanisms of their targeting to the cell wall envelope. Microbiol Mol Biol Rev 1999; 63:174-229. [PMID: 10066836 PMCID: PMC98962 DOI: 10.1128/mmbr.63.1.174-229.1999] [Citation(s) in RCA: 925] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cell wall envelope of gram-positive bacteria is a macromolecular, exoskeletal organelle that is assembled and turned over at designated sites. The cell wall also functions as a surface organelle that allows gram-positive pathogens to interact with their environment, in particular the tissues of the infected host. All of these functions require that surface proteins and enzymes be properly targeted to the cell wall envelope. Two basic mechanisms, cell wall sorting and targeting, have been identified. Cell well sorting is the covalent attachment of surface proteins to the peptidoglycan via a C-terminal sorting signal that contains a consensus LPXTG sequence. More than 100 proteins that possess cell wall-sorting signals, including the M proteins of Streptococcus pyogenes, protein A of Staphylococcus aureus, and several internalins of Listeria monocytogenes, have been identified. Cell wall targeting involves the noncovalent attachment of proteins to the cell surface via specialized binding domains. Several of these wall-binding domains appear to interact with secondary wall polymers that are associated with the peptidoglycan, for example teichoic acids and polysaccharides. Proteins that are targeted to the cell surface include muralytic enzymes such as autolysins, lysostaphin, and phage lytic enzymes. Other examples for targeted proteins are the surface S-layer proteins of bacilli and clostridia, as well as virulence factors required for the pathogenesis of L. monocytogenes (internalin B) and Streptococcus pneumoniae (PspA) infections. In this review we describe the mechanisms for both sorting and targeting of proteins to the envelope of gram-positive bacteria and review the functions of known surface proteins.
Collapse
Affiliation(s)
- W W Navarre
- Department of Microbiology & Immunology, UCLA School of Medicine, Los Angeles, California 90095, USA
| | | |
Collapse
|