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Mitchell J, Siboo IR, Takamatsu D, Chambers HF, Sullam PM. Mechanism of cell surface expression of the Streptococcus mitis platelet binding proteins PblA and PblB. Mol Microbiol 2007; 64:844-57. [PMID: 17462028 DOI: 10.1111/j.1365-2958.2007.05703.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
PblA and PblB are prophage-encoded proteins of Streptococcus mitis strain SF100 that mediate binding to human platelets. The mechanism for surface expression of these proteins has been unknown, as they do not contain signal sequences or cell wall sorting motifs. We therefore assessed whether expression of these proteins was linked the lytic cycle of the prophage. Deletion of either the holin or lysin gene resulted in retention of PblA and PblB in the cytoplasm, and loss of these proteins from the cell wall. Flow cytometric analysis revealed that induction of phage replication in SF100 produced a subpopulation of cells with increased permeability. This effect was abrogated by disruption of the holin and lysin genes. Treatment of these mutants with exogenous PblA and PblB restored surface expression, apparently via binding of the proteins to cell wall choline. Loss of PblA and PblB expression was associated with decreased platelet binding in vitro, and reduced virulence in an animal model of endocarditis. Thus, expression of PblA and PblB occurs via a novel mechanism, whereby phage induction increases bacterial permeability and release of the proteins, followed by their binding to surface of viable cells. This mechanism may be important for endovascular infection.
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Affiliation(s)
- Jennifer Mitchell
- Veterans Affairs Medical Center and the University of California, San Francisco, CA 94121, USA
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52
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Abstract
Abstract
Background
Platelets have roles other than haemostasis and many are relevant to surgical practice. This review examines both the pathophysiology of platelets in haemostasis and thrombosis, and other roles of clinical importance.
Methods
A literature review of the various functional roles of platelets was performed (Medline search, English language) including their action in inflammation (in particular in atherothrombosis), antimicrobial defence and tumour growth. Current clinical evidence for antiplatelet therapy is also reviewed.
Results and conclusion
Platelet functions are multiple, complex and not limited to haemostasis. Understanding of platelet pathophysiology continues to grow and this is relevant to many aspects of surgical practice, particularly the clinical use of antiplatelet therapy.
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Affiliation(s)
- M Troxler
- Leeds Vascular Institute, The General Infirmary at Leeds, Great George Street, Leeds LS1 3EX, UK.
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53
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Positive role of cell wall anchored proteinase PrtP in adhesion of lactococci. BMC Microbiol 2007; 7:36. [PMID: 17474995 PMCID: PMC1876236 DOI: 10.1186/1471-2180-7-36] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Accepted: 05/02/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The first step in biofilm formation is bacterial attachment to solid surfaces, which is dependent on the cell surface physico-chemical properties. Cell wall anchored proteins (CWAP) are among the known adhesins that confer the adhesive properties to pathogenic Gram-positive bacteria. To investigate the role of CWAP of non-pathogen Gram-positive bacteria in the initial steps of biofilm formation, we evaluated the physico-chemical properties and adhesion to solid surfaces of Lactococcus lactis. To be able to grow in milk this dairy bacterium expresses a cell wall anchored proteinase PrtP for breakdown of milk caseins. RESULTS The influence of the anchored cell wall proteinase PrtP on microbial surface physico-chemical properties, and consequently on adhesion, was evaluated using lactococci carrying different alleles of prtP. The presence of cell wall anchored proteinase on the surface of lactococcal cells resulted in an increased affinity to solvents with different physico-chemical properties (apolar and Lewis acid-base solvents). These properties were observed regardless of whether the PrtP variant was biologically active or not, and were not observed in strains without PrtP. Anchored PrtP displayed a significant increase in cell adhesion to solid glass and tetrafluoroethylene surfaces. CONCLUSION Obtained results indicate that exposure of an anchored cell wall proteinase PrtP, and not its proteolytic activity, is responsible for greater cell hydrophobicity and adhesion. The increased bacterial affinity to polar and apolar solvents indicated that exposure of PrtP on lactococcal cell surface could enhance the capacity to exchange attractive van der Waals interactions, and consequently increase their adhesion to different types of solid surfaces and solvents.
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54
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Antimicrobial Host Defense. Platelets 2007. [DOI: 10.1016/b978-012369367-9/50802-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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55
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56
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Abstract
It has been estimated that there are more microorganisms within and upon the human body than there are human cells. By necessity, every accessible niche must be defended by innate mechanisms to prevent invasive infection, and ideally that precludes the need for robust inflammatory responses. Yet the potential for pathogens to transcend the integument actively or passively and access the bloodstream emphasizes the need for rapid and potent antimicrobial defense mechanisms within the vascular compartment. Antimicrobial peptides from leukocytes have long been contemplated as being integral to defense against these infections. Recently, platelets are increasingly recognized for their likely multiple roles in antimicrobial host defense. Platelets and leukocytes share many structural and functional archetypes. Once activated, both cell types respond in specific ways that emphasize key roles for their antimicrobial peptides in host defense efficacy: (a) targeted accumulation at sites of tissue injury or infection; (b) direct interaction with pathogens; and (c) deployment of intracellular (leukocyte phagosomes) or extracellular (platelet secretion) antimicrobial peptides. Antimicrobial peptides from these cells exert rapid, potent, and direct antimicrobial effects against organisms that commonly access the bloodstream. Experimental models in vitro and in vivo show that antimicrobial peptides from these cells significantly contribute to prevent or limit infection. Moreover, certain platelet antimicrobial proteins are multifunctional kinocidins (microbicidal chemokines) that recruit leukocytes to sites of infection, and potentiate the antimicrobial mechanisms of these cells. In turn, pathogens pre-decorated by kinocidins may be more efficiently phagocytosed and killed by leukocytes and their antimicrobial peptide arsenal. Hence, multiple and relevant interactions between platelets and leukocytes have immunologic functions yet to be fully understood. A clearer definition of these interactions, and the antimicrobial peptide effectors contributing to these functions, will significantly advance our understanding of antimicrobial host defense against invasive infection. In addition, this knowledge may accelerate development of novel anti-infective agents and strategies against pathogens that have become refractory to conventional antimicrobials.
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Affiliation(s)
- M R Yeaman
- Division of Infectious Diseases, David Geffen School of Medicine at UCLA, LAC-Harbor UCLA Medical Center, Torrance 90502, USA.
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57
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Hicks C, Sorocco D, Levin M. Automated analysis of behavior: a computer-controlled system for drug screening and the investigation of learning. ACTA ACUST UNITED AC 2006; 66:977-90. [PMID: 16779826 DOI: 10.1002/neu.20290] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Efforts to understand cognition will be greatly facilitated by computerized systems that enable the automated analysis of animal behavior. A number of controversies in the invertebrate learning field have resulted from difficulties inherent in manual experiments. Driven by the necessity to overcome these problems during investigation of neural function in planarian flatworms and frog larvae, we designed and developed a prototype for an inexpensive, flexible system that enables automated control and analysis of behavior and learning. Applicable to a variety of small animals such as flatworms and zebrafish, this system allows automated analysis of innate behavior, as well as of learning and memory in a plethora of conditioning paradigms. We present here the schematics of a basic prototype, which overcomes experimenter effects and operator tedium, enabling a large number of animals to be analyzed with transparent on-line access to primary data. A scaled-up version of this technology represents an efficient methodology to screen pharmacological and genetic libraries for novel neuroactive reagents of basic and biomedical relevance.
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Affiliation(s)
- Caitlin Hicks
- Forsyth Center for Regenerative and Developmental Biology, The Forsyth Institute, Boston, Massachusetts 02115, USA
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58
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Loeffler JM, Fischetti VA. Lysogeny of Streptococcus pneumoniae with MM1 phage: improved adherence and other phenotypic changes. Infect Immun 2006; 74:4486-95. [PMID: 16861634 PMCID: PMC1539626 DOI: 10.1128/iai.00020-06] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pneumococcal prophages are extremely frequent, but no role in pathogenesis has so far been attributed to them. We isolated a variant of phage MM1, named MM1-1998, from a serotype 24 strain of Streptococcus pneumoniae. We created three isogenic strain pairs (serotypes 3, 4, and 24) that differed only by the lysogenic presence of the MM1-1998 phage and did a phenotypic comparison. Lysogeny led to improved adherence to inert surfaces and pharyngeal cells compared to that with the cured variants of the strains. We found that lysogeny with MM1-1998 coincided with a more transparent phenotype and phage curing with more opaque colonies in all strain pairs, and we discovered that transparency was associated with more successful and stable lysogeny. Since transparency alone was possibly responsible for the adherence difference, we further compared the TIGR4 lysogen with an equally transparent variant of TIGR4 in order to reassess the role of phage or transparency separately. The results revealed that improved adherence was independently associated with lysogeny with the MM1-1998 phage. Other phenotypic differences such as faster growth, increased autolysis, and decreased intracellular hemolytic activity were more likely due to transparency. By improving the adherence of pneumococci, this prophage may contribute to their fitness and possibly to their persistence in humans.
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Affiliation(s)
- Jutta M Loeffler
- Laboratory of Bacterial Pathogenesis, The Rockefeller University, 1230 York Ave., New York, New York 10021, USA
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59
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Takamatsu D, Bensing BA, Prakobphol A, Fisher SJ, Sullam PM. Binding of the streptococcal surface glycoproteins GspB and Hsa to human salivary proteins. Infect Immun 2006; 74:1933-40. [PMID: 16495569 PMCID: PMC1418684 DOI: 10.1128/iai.74.3.1933-1940.2006] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
GspB and Hsa are homologous surface glycoproteins of Streptococcus gordonii that bind sialic acid moieties on platelet membrane glycoprotein Ibalpha. Since this species is an important member of the oral flora, we examined the direct binding of these adhesins to human salivary proteins. Both GspB and Hsa bound low-molecular-weight salivary mucin MG2 and salivary agglutinin. Hsa also bound several other salivary proteins, including secretory immunoglobulin A. Screening of six oral streptococcal isolates revealed that at least two of the strains expressed GspB homologues. These results indicate that GspB-like adhesins may be important for oral bacterial colonization.
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Affiliation(s)
- Daisuke Takamatsu
- Division of Infectious Diseases, VA Medical Center (111W), 4150 Clement Street, San Francisco, CA 94121, USA
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60
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Abstract
In recent years, the frequency of serious cardiovascular infections such as endocarditis has increased, particularly in association with nosocomially acquired antibiotic-resistant pathogens. Growing evidence suggests a crucial role for the interaction of bacteria with human platelets in the pathogenesis of cardiovascular infections. Here, we review the nature of the interactions between platelets and bacteria, and the role of these interactions in the pathogenesis of endocarditis and other cardiovascular diseases.
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Affiliation(s)
- J Ross Fitzgerald
- Centre for Infectious Diseases, The Chancellor's Building, New Royal Infirmary, University of Edinburgh, Edinburgh EH16 4SB, Scotland, UK
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61
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Shen K, Gladitz J, Antalis P, Dice B, Janto B, Keefe R, Hayes J, Ahmed A, Dopico R, Ehrlich N, Jocz J, Kropp L, Yu S, Nistico L, Greenberg DP, Barbadora K, Preston RA, Post JC, Ehrlich GD, Hu FZ. Characterization, distribution, and expression of novel genes among eight clinical isolates of Streptococcus pneumoniae. Infect Immun 2006; 74:321-30. [PMID: 16368987 PMCID: PMC1346598 DOI: 10.1128/iai.74.1.321-330.2006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Eight low-passage-number Streptococcus pneumoniae clinical isolates, each of a different serotype and a different multilocus sequence type, were obtained from pediatric participants in a pneumococcal vaccine trial. Comparative genomic analyses were performed with these strains and two S. pneumoniae reference strains. Individual genomic libraries were constructed for each of the eight clinical isolates, with an average insert size of approximately 1 kb. A total of 73,728 clones were picked for arraying, providing more than four times genomic coverage per strain. A subset of 4,793 clones were sequenced, for which homology searches revealed that 750 (15.6%) of the sequences were unique with respect to the TIGR4 reference genome and 263 (5.5%) clones were unrelated to any available streptococcal sequence. Hypothetical translations of the open reading frames identified within these novel sequences showed homologies to a variety of proteins, including bacterial virulence factors not previously identified in S. pneumoniae. The distribution and expression patterns of 58 of these novel sequences among the eight clinical isolates were analyzed by PCR- and reverse transcriptase PCR-based analyses, respectively. These unique sequences were nonuniformly distributed among the eight isolates, and transcription of these genes in planktonic cultures was detected in 81% (172/212) of their genic occurrences. All 58 novel sequences were transcribed in one or more of the clinical strains, suggesting that they all correspond to functional genes. Sixty-five percent (38/58) of these sequences were found in 50% or less of the clinical strains, indicating a significant degree of genomic plasticity among natural isolates.
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Affiliation(s)
- Kai Shen
- Center for Genomic Sciences, Allegheny-Singer Research Institute, Allegheny General Hospital, 320 East North Avenue, 11th Floor South Tower, Pittsburgh, PA 15212, USA
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62
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Jalah R, Sarin R, Sud N, Alam MT, Parikh N, Das TK, Sharma YD. Identification, expression, localization and serological characterization of a tryptophan-rich antigen from the human malaria parasite Plasmodium vivax. Mol Biochem Parasitol 2005; 142:158-69. [PMID: 15869815 DOI: 10.1016/j.molbiopara.2005.01.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2004] [Revised: 01/11/2005] [Accepted: 01/26/2005] [Indexed: 11/26/2022]
Abstract
Plasmodium vivax is most common but non-cultivable human malaria parasite which is poorly characterized at the molecular level. Here, we describe the identification and characterization of a P. vivax Tryptophan-Rich Antigen (PvTRAg) which contains unusually high (8.28%) tryptophan residues and is expressed by all blood stages of the parasite. The pvtrag gene comprises a 978bp open reading frame interrupted by two introns. The first intron is located in the 5'-untranslated region while the second one is positioned 174bp downstream to the ATG codon. The encoded approximately 40kDa protein contains a transmembrane domain near the N-terminus followed by a tryptophan-rich domain with significantly high surface probability and antigenic index. It is localized in the parasite cytoplasm as well as in the cytoplasm of the parasitized erythrocyte. The purified E. coli expressed recombinant PvTRAg protein showed a very high seropositivity rate for the presence of antibodies amongst the P. vivax patients, indicating that the antigen generates significant humoral immune response during the natural course of P. vivax infection. Analysis of various field isolates revealed that the tryptophan-rich domain is highly conserved except for three-point mutations. The PvTRAg could be a potential vaccine candidate since similar tryptophan-rich antigens of P. yoelii have shown protection against malaria in murine model.
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Affiliation(s)
- Rashmi Jalah
- Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India
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63
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Kropinski AM, Hayward M, Agnew MD, Jarrell KF. The genome of BCJA1c: a bacteriophage active against the alkaliphilic bacterium, Bacillus clarkii. Extremophiles 2004; 9:99-109. [PMID: 15841342 DOI: 10.1007/s00792-004-0425-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Accepted: 09/17/2004] [Indexed: 10/26/2022]
Abstract
The sequence of the genome of the first alkaliphilic bacteriophage has been determined. Temperate phage BCJA1 possesses a terminally redundant genome of approximately 41 kb, with a mol% G + C content of 41.7 and 59 genes arranged predominantly into two divergent transcriptons. The integrase gene of this phage is unique in that it contains a ribosomal slippage site. While this type of translational regulation occurs in the synthesis of transposase, this is the first time that it has been observed in a bacteriophage integrase. The DNA replication, recombination, packaging, and morphogenesis proteins show their greatest sequence similarity to phages and prophages from the genus Streptococcus. Host specificity, lysin, and lysogeny maintenance functions are most closely related to genes from Bacillus species.
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Affiliation(s)
- Andrew M Kropinski
- Department of Microbiology and Immunology, Queens University, Kingston, ON, K7L 3N6, Canada.
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64
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Chia JS, Lin YL, Lien HT, Chen JY. Platelet aggregation induced by serotype polysaccharides from Streptococcus mutans. Infect Immun 2004; 72:2605-17. [PMID: 15102769 PMCID: PMC387875 DOI: 10.1128/iai.72.5.2605-2617.2004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Platelet aggregation plays an important role in the pathogenesis of infective endocarditis induced by viridans streptococci or staphylococci. Aggregation induced in vitro involves direct binding of bacteria to platelets through multiple surface components. Using platelet aggregometry, we demonstrated in this study that two Streptococcus mutans laboratory strains, GS-5 and Xc, and two clinical isolates could aggregate platelets in an irreversible manner in rabbit platelet-rich plasma preparations. The aggregation was partially inhibited by prostaglandin I(2) (PGI(2)) in a dose-dependent manner. Whole bacteria and heated bacterial cell wall extracts were able to induce aggregation. Cell wall polysaccharides extracted from the wild-type Xc strain, containing serotype-specific polysaccharides which are composed of rhamnose-glucose polymers (RGPs), could induce platelet aggregation in the presence of plasma. Aggregation induced by the serotype-specific RGP-deficient mutant Xc24R was reduced by 50% compared to the wild-type strain Xc. In addition, cell wall polysaccharides extracted from Xc24R failed to induce platelet aggregation. The Xc strain, but not the Xc24R mutant, could induce platelet aggregation when preincubated with plasma. Both Xc and Xc24R failed to induce platelets to aggregate in plasma depleted of immunoglobulin G (IgG), but aggregation was restored by replenishment of anti-serotype c IgG. Analysis by flow cytometry showed that S. mutans RGPs could bind directly to rabbit and human platelets. Furthermore, cell wall polysaccharides extracted from the Xc, but not the Xc24R, strain could induce pseudopod formation of both rabbit and human platelets in the absence of plasma. Distinct from the aggregation of rabbit platelets, bacterium-triggered aggregation of human platelets required a prolonged lag phase and could be blocked completely by PGI(2). RGPs also trigger aggregation of human platelets in a donor-dependent manner, either as a transient and reversible or a complete and irreversible response. These results indicated that serotype-specific RGPs, a soluble product of S. mutans, could directly bind to and activate platelets from both rabbit and human. In the presence of plasma containing IgG specific to RGPs, RGPs could trigger aggregation of both human and rabbit platelets, but the degree of aggregation in human platelets depends on the donors.
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Affiliation(s)
- Jean-San Chia
- Department of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China.
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65
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Takamatsu D, Bensing BA, Sullam PM. Genes in the accessory sec locus of Streptococcus gordonii have three functionally distinct effects on the expression of the platelet-binding protein GspB. Mol Microbiol 2004; 52:189-203. [PMID: 15049820 DOI: 10.1111/j.1365-2958.2004.03978.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Platelet binding by Streptococcus gordonii strain M99 is strongly correlated with the expression of the large surface glycoprotein GspB. A 14 kb chromosomal region downstream of gspB was previously shown to be required for the expression of this protein. The region encodes SecA2 and SecY2, which are components of an accessory secretion system dedicated specifically to the export of GspB. The region also includes three genes (gly, nss and gtf) that encode proteins likely to function in carbohydrate metabolism, and four genes (orf1-4) that encode proteins of unknown function. In this report, we have investigated the role of these genes in GspB expression. We found that disruption of orf1, orf2 or orf3 resulted in a loss of GspB export and the intracellular accumulation of GspB. As they are apparently essential components of the accessory secretion system, these genes were renamed asp1-3 (for accessory secretory protein). In gtf and orf4 mutants, gspB was transcribed, but no GspB was detected. These results suggest that Gtf and Orf4 are required for the translation or for the stability of GspB. In contrast, gly and nss mutants were able to express and export GspB. However, disruption of these genes appeared to affect the carbohydrate composition of this glycoprotein. As asp1-3, gtf and orf4, but not gly and nss, are conserved in the accessory sec loci of several staphylococcal and streptococcal species, these genes may also have crucial roles in the expression and export of GspB homologues in the other Gram-positive bacteria.
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Affiliation(s)
- Daisuke Takamatsu
- Division of Infectious Diseases, Veterans Affairs Medical Center (111W) and the University of California, 4150 Clement Street, San Francisco, CA 94121, USA
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66
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Siboo IR, Bensing BA, Sullam PM. Genomic organization and molecular characterization of SM1, a temperate bacteriophage of Streptococcus mitis. J Bacteriol 2004; 185:6968-75. [PMID: 14617660 PMCID: PMC262713 DOI: 10.1128/jb.185.23.6968-6975.2003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The direct binding of Streptococcus mitis to human platelets is mediated in part by two proteins (PblA and PblB) encoded by a lysogenic bacteriophage (SM1). Since SM1 is the first prophage of S. mitis that has been identified and because of the possible role of these phage-encoded proteins in virulence, we sought to characterize SM1 in greater detail. Sequencing of the SM1 genome revealed that it consisted of 34,692 bp, with an overall G+C content of 39 mol%. Fifty-six genes encoding proteins of 40 or more amino acids were identified. The genes of SM1 appear to be arranged in a modular, life cycle-specific organization. BLAST analysis also revealed that the proteins of SM1 have homologies to proteins from a wide variety of lambdoid phages. Bioinformatic analyses, in addition to N-terminal sequencing of the proteins, led to the assignment of possible functions to a number of proteins, including the integrase, the terminase, and two major structural proteins. Examination of the phage structural components indicates that the phage head may assemble using stable multimers of the major capsid protein, in a process similar to that of phage r1t. These findings indicate that SM1 may be part of a discrete subfamily of the Siphoviridae that includes at least phages r1t of Lactococcus lactis and SF370.3 of Streptococcus pyogenes.
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Affiliation(s)
- Ian R Siboo
- Veterans Affairs Medical Center and University of California, San Francisco, California 94121, USA
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67
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Boyd EF, Brüssow H. Common themes among bacteriophage-encoded virulence factors and diversity among the bacteriophages involved. Trends Microbiol 2002; 10:521-9. [PMID: 12419617 DOI: 10.1016/s0966-842x(02)02459-9] [Citation(s) in RCA: 246] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
There are common themes among bacteriophage-encoded virulence factors, which include the well-characterized bacterial toxins and proteins that alter antigenicity as well as several new classes of bacteriophage-encoded proteins such as superantigens, effectors translocated by a type III secretion system, and proteins required for intracellular survival and host cell attachment. These virulence factors are encoded by a diversity of bacteriophages, members of the viral families Siphoviridae, Podoviridae, Myoviridae and Inoviridae, with some bacteriophages having characteristics of more than one virus family. The location of virulence genes within the bacteriophage genomes is non-random and consistent with an origin via imprecise prophage excision or as either transferable cassettes or integral components of the bacteriophage genome.
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Affiliation(s)
- E Fidelma Boyd
- Dept of Microbiology, UCC, National University of Ireland, Cork, Ireland
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68
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Tettelin H, Masignani V, Cieslewicz MJ, Eisen JA, Peterson S, Wessels MR, Paulsen IT, Nelson KE, Margarit I, Read TD, Madoff LC, Wolf AM, Beanan MJ, Brinkac LM, Daugherty SC, DeBoy RT, Durkin AS, Kolonay JF, Madupu R, Lewis MR, Radune D, Fedorova NB, Scanlan D, Khouri H, Mulligan S, Carty HA, Cline RT, Van Aken SE, Gill J, Scarselli M, Mora M, Iacobini ET, Brettoni C, Galli G, Mariani M, Vegni F, Maione D, Rinaudo D, Rappuoli R, Telford JL, Kasper DL, Grandi G, Fraser CM. Complete genome sequence and comparative genomic analysis of an emerging human pathogen, serotype V Streptococcus agalactiae. Proc Natl Acad Sci U S A 2002; 99:12391-6. [PMID: 12200547 PMCID: PMC129455 DOI: 10.1073/pnas.182380799] [Citation(s) in RCA: 395] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2002] [Accepted: 06/26/2002] [Indexed: 11/18/2022] Open
Abstract
The 2,160,267 bp genome sequence of Streptococcus agalactiae, the leading cause of bacterial sepsis, pneumonia, and meningitis in neonates in the U.S. and Europe, is predicted to encode 2,175 genes. Genome comparisons among S. agalactiae, Streptococcus pneumoniae, Streptococcus pyogenes, and the other completely sequenced genomes identified genes specific to the streptococci and to S. agalactiae. These in silico analyses, combined with comparative genome hybridization experiments between the sequenced serotype V strain 2603 V/R and 19 S. agalactiae strains from several serotypes using whole-genome microarrays, revealed the genetic heterogeneity among S. agalactiae strains, even of the same serotype, and provided insights into the evolution of virulence mechanisms.
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Affiliation(s)
- Herve Tettelin
- The Institute for Genomic Research, 9712 Medical Center Drive, Rockville, MD 20850, USA
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69
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Affiliation(s)
- Patrick L Wagner
- Howard Hughes Medical Institute and New England Medical Center, Boston, Massachusetts 02110, USA
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70
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Moreillon P, Que YA, Bayer AS. Pathogenesis of streptococcal and staphylococcal endocarditis. Infect Dis Clin North Am 2002; 16:297-318. [PMID: 12092474 DOI: 10.1016/s0891-5520(01)00009-5] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Although streptococcal and S. aureus IE share the same primary site of infection, their pathogenesis and clinical evolution present several major differences. Streptococci adhere to cardiac valves with pre-existing endothelial lesions. In contrast, S. aureus can colonize either damaged endothelium or invade physically intact endothelial cells. These interactions are mediated by multiple surface adhesins, some of which have been only partially characterized. Streptococci produce surface glucans (gtf and ftf), ECM adhesins (e.g., fibronectin-binding proteins, FimA), and platelet aggregating factors (phase I and phase II antigens, pblA, pblB, and pblT), all of which have been.
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Affiliation(s)
- Philippe Moreillon
- Division of Infectious Diseases, Centre Hospitalier Universitaire Vaudois, BH19 Rue du Bugnon, 1011 Lausanne, Switzerland.
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Bensing BA, Sullam PM. An accessory sec locus of Streptococcus gordonii is required for export of the surface protein GspB and for normal levels of binding to human platelets. Mol Microbiol 2002; 44:1081-94. [PMID: 12010500 DOI: 10.1046/j.1365-2958.2002.02949.x] [Citation(s) in RCA: 204] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The translocation of proteins across the bacterial cell membrane is carried out by highly conserved components of the Sec system. Most bacterial species have a single copy of the genes encoding SecA and SecY, which are essential for viability. However, Streptococcus gordonii strain M99 encodes SecA and SecY homologues that are not required for viability or for the translocation of most exported proteins. The genes (secA2 and secY2) reside in a region of the chromosome required for the export of GspB, a 286 kDa cell wall-anchored protein. Loss of GspB surface expression is associated with a significant reduction in the binding of M99 to human platelets, suggesting that it may be an adhesin. Genetic analyses indicate that M99 has a second, canonical SecA homologue that is essential for viability. At least two other Gram-positive species, Streptococcus pneumoniae and Staphylococcus aureus, encode two sets of SecA and SecY homologues. One set is more similar to SecA and SecY of Escherichia coli, whereas the other set is more similar to SecA2 and SecY2 of strain M99. The conserved organization of genes in the secY2-secA2 loci suggests that, in each of these Gram-positive species, SecA2 and SecY2 may constitute a specialized system for the transport of a very large serine-rich repeat protein.
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Affiliation(s)
- Barbara A Bensing
- Division of Infectious Diseases, Veterans Affairs Medical Center (111W) and the University of California, 4150 Clement Street, San Francisco, CA 94121, USA
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Bensing BA, Siboo IR, Sullam PM. Proteins PblA and PblB of Streptococcus mitis, which promote binding to human platelets, are encoded within a lysogenic bacteriophage. Infect Immun 2001; 69:6186-92. [PMID: 11553559 PMCID: PMC98750 DOI: 10.1128/iai.69.10.6186-6192.2001] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The binding of platelets by bacteria is a proposed central mechanism in the pathogenesis of infective endocarditis. Platelet binding by Streptococcus mitis strain SF100 (an endocarditis isolate) was recently shown to be mediated in part by the surface proteins PblA and PblB. The genes encoding PblA and PblB are clustered with genes nearly identical to those of streptococcal phages r1t, 01205, and Dp-1, suggesting that pblA and pblB might reside within a prophage. To address this possibility, cultures of SF100 were exposed to either mitomycin C or UV light, both of which are known to induce the lytic cycle of many temperate phages. Both treatments caused a significant increase in the transcription of pblA. Treatment with mitomycin C or UV light also caused a substantial increase in the expression of PblA and PblB, as detected by Western blot analysis of proteins in the SF100 cell wall. By electron microscopy, phage particles were readily visible in the supernatants from induced cultures of SF100. The phage, designated SM1, had a double-stranded DNA genome of approximately 35 kb. Southern blot analysis of phage DNA indicated that pblA and pblB were contained within the SM1 genome. Furthermore, Western blot analysis of phage proteins revealed that both PblA and PblB were present in the phage particles. These findings indicate that PblA and PblB are encoded by a lysogenic bacteriophage, which could facilitate the dissemination of these potential virulence determinants to other bacterial pathogens.
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Affiliation(s)
- B A Bensing
- Veterans Affairs Medical Center and the University of California, San Francisco, California 94121, USA
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