Variation in M protein production among Streptococcus pyogenes strains according to emm genotype

Masakado Matsumoto, Masahiro Suzuki, Kaoru Hirose, Reiji Hiramatsu, Hiroko Minagawa, Masaaki Minami, Ichiro Tatsuno, Akira Okamoto, Michio Ohta, Tadao Hasegawa

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2 Citations (Scopus)


M protein is an important virulence determinant in Streptococcus pyogenes, but the amounts of M protein in various strains of the species remain to be elucidated. To assess the amount of M protein in strains of each emm genotype, dot blot analysis was performed on 141 clinically isolated strains. Among the cell membrane-associated proteins, M protein was present in greater quantities in the emm1, 3, and 6 strains than in the other emm strains. In addition three strains, one each of the emm1, 3, and 6 types, showed prolific M protein production (M protein-high producers). These three emm genotypes are frequently isolated in clinical practice. Sequencing of the csrRS gene, one of the two-component signal transduction systems implicated in virulence, was performed on 25 strains bearing different amounts of M protein. CsrS mutations, in contrast to CsrR protein, were detected in 11 strains. The M protein-high producer strain of emm1 type carried two amino acid substitutions, whereas the other three emm1 strains carried only one substitution each. The M protein-high producer expressed its emm gene more strongly than the corresponding M protein-low producer did according to TaqMan RT-PCR. These observations suggest that the accumulation of amino acid substitutions in CsrS protein may contribute, at least in part, to the large amount of M protein production seen in several emm genotypes.

Original languageEnglish
Pages (from-to)379-387
Number of pages9
Issue number6
Publication statusPublished - 06-2011
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Immunology
  • Virology


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