title: Naturally occurring single amino acid replacements in a regulatory protein alter streptococcal gene expression and virulence in mice.
abstract: Infection with different strains of the same species of bacteria often results in vastly different clinical outcomes. Despite extensive investigation, the genetic basis of microbial strain-specific virulence remains poorly understood. Recent whole-genome sequencing has revealed that SNPs are the most prevalent form of genetic diversity among different strains of the same species of bacteria. For invasive serotype M3 group A streptococci (GAS) strains, the gene encoding regulator of proteinase B (RopB) has the highest frequency of SNPs. Here, we have determined that ropB polymorphisms alter RopB function and modulate GAS host-pathogen interactions. Sequencing of ropB in 171 invasive serotype M3 GAS strains identified 19 distinct ropB alleles. Inactivation of the ropB gene in strains producing distinct RopB variants had dramatically divergent effects on GAS global gene expression. Additionally, generation of isoallelic GAS strains differing only by a single amino acid in RopB confirmed that variant proteins affected transcript levels of the gene encoding streptococcal proteinase B, a major RopB-regulated virulence factor. Comparison of parental, RopB-inactivated, and RopB isoallelic strains in mouse infection models demonstrated that ropB polymorphisms influence GAS virulence and disease manifestations. These data detail a paradigm in which unbiased, whole-genome sequence analysis of populations of clinical bacterial isolates creates new avenues of productive investigation into the pathogenesis of common human infections.
authors.affiliation: Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, and Department of Pathology and Laboratory Medicine, The Methodist Hospital, Houston, Texas, USA.
authors.forename: Ronan K
authors.initials: RK
authors.lastname: Carroll
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Shelburne
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Olsen
authors.forename: Bryce
authors.initials: B
authors.lastname: Suber
authors.forename: Pranoti
authors.initials: P
authors.lastname: Sahasrabhojane
authors.forename: Muthiah
authors.initials: M
authors.lastname: Kumaraswami
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Beres
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Shea
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Flores
authors.forename: James M
authors.initials: JM
authors.lastname: Musser
mesh_terms: D000483:Alleles; D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism; D004247:DNA / Q000737:chemistry; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007700:Kinetics; D051379:Mice; D020641:Polymorphism, Single Nucleotide; D011487:Protein Conformation; D013291:Streptococcus / Q000235:genetics / Q000378:metabolism*; D014774:Virulence; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; C098249:RopB protein, Rhizobium leguminosarum; D037521:Virulence Factors; D004247:DNA