Progress toward characterization of the group A Streptococcus metagenome: complete genome sequence of a macrolide-resistant serotype M6 strain

J Infect Dis. 2004 Aug 15;190(4):727-38. doi: 10.1086/422697. Epub 2004 Jul 20.


We describe the genome sequence of a macrolide-resistant strain (MGAS10394) of serotype M6 group A Streptococcus (GAS). The genome is 1,900,156 bp in length, and 8 prophage-like elements or remnants compose 12.4% of the chromosome. A 8.3-kb prophage remnant encodes the SpeA4 variant of streptococcal pyrogenic exotoxin A. The genome of strain MGAS10394 contains a chimeric genetic element composed of prophage genes and a transposon encoding the mefA gene conferring macrolide resistance. This chimeric element also has a gene encoding a novel surface-exposed protein (designated "R6 protein"), with an LPKTG cell-anchor motif located at the carboxyterminus. Surface expression of this protein was confirmed by flow cytometry. Humans with GAS pharyngitis caused by serotype M6 strains had antibody against the R6 protein present in convalescent, but not acute, serum samples. Our studies add to the theme that GAS prophage-encoded extracellular proteins contribute to host-pathogen interactions in a strain-specific fashion.

Publication types

  • Comparative Study

MeSH terms

  • Alleles
  • Amino Acid Motifs / genetics
  • Antibodies, Bacterial / blood
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Proteins / genetics
  • Bacterial Proteins / immunology
  • Blotting, Western
  • Child
  • Drug Resistance, Bacterial / genetics
  • Exotoxins / genetics
  • Flow Cytometry
  • Genome, Bacterial*
  • Humans
  • Macrolides / pharmacology*
  • Membrane Proteins / genetics
  • Membrane Proteins / immunology
  • Pharyngitis / blood
  • Pharyngitis / microbiology
  • R Factors / genetics*
  • Streptococcal Infections / blood
  • Streptococcal Infections / microbiology
  • Streptococcus Phages / genetics
  • Streptococcus pyogenes / drug effects
  • Streptococcus pyogenes / genetics*
  • Streptococcus pyogenes / isolation & purification


  • Antibodies, Bacterial
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Exotoxins
  • Macrolides
  • MefA protein, Streptococcus
  • Membrane Proteins
  • SpeA protein, Streptococcus pyogenes