Identification of a gene that regulates expression of M protein, the major virulence determinant of group A streptococci

M. G. Caparon, J. R. Scott

Research output: Contribution to journalArticle

125 Scopus citations

Abstract

By using Tn916 insertional mutagenesis, we have identified mry (M protein RNA yield), a gene required for high-level expression of the M protein, an essential virulence determinant of the group A streptococcus. The mru::Tn916 mutation causes a reduction by a factor of ≃50 in the amount of M protein produced, in the original strain and in a nonmutagenized host to which the mutation was transferred by transduction. The insertion is located ≃1.8 kilobases upstream of the structural gene for M protein (emm) and its promoter. The genomic region including mry::Tn916 and emm was cloned on a cosmid vector and introduced into Escherichia coli. When the transposon excised precisely from the chimeric cosmid in E. coli, the resulting streptococcal DNA showed the same restriction pattern as the homologous chromosomal region in the parental nonmutagenized streptococcus. The sequence of the promoter for emm was not altered in the mry mutant. The reduction in protein correlates with a decrease in the amount of M protein-specific mRNA, indicating that mry regulates transcription of emm.

Original languageEnglish
Pages (from-to)8677-8681
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume84
Issue number23
DOIs
StatePublished - Jan 1 1987
Externally publishedYes

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