Journal article
Genome Diversification in Staphylococcus aureus: Molecular Evolution of a Highly Variable Chromosomal Region Encoding the Staphylococcal Exotoxin-Like Family of Proteins
Infection and immunity, Vol.71(5), pp.2827-2838
05/2003
DOI: 10.1128/IAI.71.5.2827-2838.2003
PMCID: PMC153281
PMID: 12704157
Abstract
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.
Details
- Title: Subtitle
- Genome Diversification in Staphylococcus aureus: Molecular Evolution of a Highly Variable Chromosomal Region Encoding the Staphylococcal Exotoxin-Like Family of Proteins
- Creators
- J. Ross Fitzgerald - Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455Sean D Reid - Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455Eeva Ruotsalainen - Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455Timothy J Tripp - Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455MengYao Liu - Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455Robert Cole - Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455Pentti Kuusela - Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455Patrick M Schlievert - Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455Asko Järvinen - Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455James M Musser - Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455
- Resource Type
- Journal article
- Publication Details
- Infection and immunity, Vol.71(5), pp.2827-2838
- DOI
- 10.1128/IAI.71.5.2827-2838.2003
- PMID
- 12704157
- PMCID
- PMC153281
- NLM abbreviation
- Infect Immun
- ISSN
- 0019-9567
- eISSN
- 1098-5522
- Publisher
- American Society for Microbiology
- Language
- English
- Date published
- 05/2003
- Academic Unit
- Microbiology and Immunology; Internal Medicine
- Record Identifier
- 9984001228702771
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