Dataset Information

Genetic diversity of staphylocoagulase genes (coa): insight into the evolution of variable chromosomal virulence factors in Staphylococcus aureus.

ABSTRACT: BACKGROUND: The production of staphylocoagulase (SC) causing the plasma coagulation is one of the important characteristics of Staphylococcus aureus. Although SCs have been classified into 10 serotypes based on the differences in the antigenicity, genetic bases for their diversities and relatedness to chromosome types are poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: We compared the nucleotide sequences of 105 SC genes (coa), 59 of which were determined in this study. D1 regions, which contain prothrombin-activating and -binding domains and are presumed to be the binding site of each type-specific antiserum, were classified into twelve clusters having more than 90% nucleotide identities, resulting to create two novel SC types, XI and XII, in addition to extant 10 types. Nine of the twelve SC types were further subdivided into subtypes based on the differences of the D2 or the central regions. The phylogenetical relations of the D1 regions did not correlate exactly with either one of agr types and multilocus sequence types (STs). In addition, genetic analysis showed that recombination events have occurred in and around coa. So far tested, STs of 126 S. aureus strains correspond to the combination of SC type and agr type except for the cases of CC1 and CC8, which contained two and three different SC types, respectively. CONCLUSION: The data suggested that the evolution of coa was not monophyletic in the species. Chromosomal recombination had occurred at coa and agr loci, resulting in the carriage of the combinations of allotypically different important virulence determinants in staphylococcal chromosome.

SUBMITTER: Watanabe S

PROVIDER: S-EPMC2683563 | biostudies-literature | 2009

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Genetic diversity of staphylocoagulase genes (coa): insight into the evolution of variable chromosomal virulence factors in Staphylococcus aureus.

Watanabe Shinya S Ito Teruyo T Sasaki Takashi T Li Shanshuang S Uchiyama Ikuo I Kishii Kozue K Kikuchi Ken K Skov Robert Leo RL Hiramatsu Keiichi K

PloS one 20090527 5

<h4>Background</h4>The production of staphylocoagulase (SC) causing the plasma coagulation is one of the important characteristics of Staphylococcus aureus. Although SCs have been classified into 10 serotypes based on the differences in the antigenicity, genetic bases for their diversities and relatedness to chromosome types are poorly understood.<h4>Methodology/principal findings</h4>We compared the nucleotide sequences of 105 SC genes (coa), 59 of which were determined in this study. D1 region ...[more]

PMID: 19492076

Similar Datasets

Project description:Recent genomic studies have revealed extensive variation in natural populations of many pathogenic bacteria. However, the evolutionary processes which contribute to much of this variation remain unclear. A previous whole-genome DNA microarray study identified variation at a large chromosomal region (RD13) of Staphylococcus aureus which encodes a family of proteins with homology to staphylococcal and streptococcal superantigens, designated staphylococcal exotoxin-like (SET) proteins. In the present study, RD13 was found in all 63 S. aureus isolates of divergent clonal, geographic, and disease origins but contained a high level of variation in gene content in different strains. A central variable region which contained from 6 to 10 different set genes, depending on the strain, was identified, and DNA sequence analysis suggests that horizontal gene transfer and recombination have contributed to the diversification of RD13. Phylogenetic analysis based on the RD13 DNA sequence of 18 strains suggested that loss of various set genes has occurred independently several times, in separate lineages of pathogenic S. aureus, providing a model to explain the molecular variation of RD13 in extant strains. In spite of multiple episodes of set deletion, analysis of the ratio of silent substitutions in set genes to amino acid replacements in their products suggests that purifying selection (selective constraint) is acting to maintain SET function. Further, concurrent transcription in vitro of six of the seven set genes in strain COL was detected, indicating that the expression of set genes has been maintained in contemporary strains, and Western immunoblot analysis indicated that multiple SET proteins are expressed during the course of human infections. Overall, we have shown that the chromosomal region RD13 has diversified extensively through episodes of gene deletion and recombination. The coexpression of many set genes and the production of multiple SET proteins during human infection suggests an important role in host-pathogen interactions.

Project description:Staphylococcus aureus causes localized infections or invasive diseases (abscesses or endocarditis). One of its virulence factors is staphylocoagulase (SCG), which binds prothrombin to form a complex with thrombin-like proteolytic activity and leads to uncontrolled fibrin generation at sites of bacterial inoculation. The aim of this study was to characterize the formation, structure, mechanical properties and lysis of SCG-generated clots. Recombinant SCG was expressed in Escherichia coli, purified and the amidolytic activity of its complexes with human prothrombin (SCG-PT) and thrombin (SCG-T) was determined using human thrombin as a reference. Fibrin clots were prepared from purified fibrinogen and human plasma using thrombin, SCG-PT or SCG-T as a coagulase. The kinetics of clot formation and lysis by tissue-type plasminogen activator (tPA) were monitored with turbidimetric assays. Fibrin ultrastructure was examined with scanning electron microscopy and small-angle X-ray scattering (SAXS). Fibrin clot porosity was characterized with fluid permeation assays, whereas the viscoelastic properties and mechanical stability were evaluated with oscillation rheometry. Compared to thrombin, the amidolytic and clotting activity of SCG-PT was 1.6- to 2.5-fold lower on a molar basis. SCG-T had equivalent amidolytic, but reduced clotting activity both on pure fibrinogen (1.6-fold), and in plasma (1.3-fold). The SCG-PT and SCG-T generated fibrin with thicker fibers (10-60% increase in median diameter) than thrombin due to increased number of fibrin protofibrils per fiber cross-section. According to the fluid permeability of the clots SCG-PT and SCG-T promoted the formation of more porous structures. The shear stress resistance in the pure fibrin and plasma clots generated by SCG-PT was significantly lower than in the thrombin clots (243.8 ± 22.0 Pa shear stress was sufficient for disassembly of SCG-PT fibrin vs. 937.3 ± 65.6 Pa in thrombin clots). The tPA-mediated lysis of both pure fibrin and plasma clots produced by SCG-PT or SCG-T was accelerated compared to thrombin, resulting in up to a 2.1-fold increase in tPA potency. Our results indicate that SCG generates a thrombus scaffold with a structure characterized by impaired mechanical stability and increased lytic susceptibility. This proneness to clot disintegration could have implications in the septic embolism from endocardial bacterial vegetation.

Dataset Information

Genetic diversity of staphylocoagulase genes (coa): insight into the evolution of variable chromosomal virulence factors in Staphylococcus aureus.

Publications

Genetic diversity of staphylocoagulase genes (coa): insight into the evolution of variable chromosomal virulence factors in Staphylococcus aureus.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets