Evidence consistent with horizontal transfer of the gene (emm12) encoding serotype M12 protein between group A and group G pathogenic streptococci.
Human isolates of Lancefield group G streptococci harbor sequences homologous with the structural gene (emm) encoding M protein, a major virulence factor in Streptococcus pyogenes (a group A Streptococcus species). We used DNA-DNA hybridization, restriction endonuclease chromosomal profiling, and multilocus enzyme electrophoresis to examine genetic relationships between group A and group G streptococcal strains expressing homologous serologic type 12 M (M12) protein. All M12 group A strains studied had very similar restriction endonuclease genomic profiles and multilocus enzyme genotypes. In contrast, the restriction enzyme genomic profile and multilocus enzyme genotype of the M12 group G strain CS140 were strikingly different from those characterizing the M12 group A organisms. DNA-DNA hybridization studies revealed, on average, 57% genomic similarity between the M12 group A and group G strains. Taken together, our data demonstrate that a gene encoding M12 protein occurs in two highly divergent chromosomal backgrounds, a result suggesting that an episode of horizontal gene transfer and recombination has occurred between two streptococcal lineages.
Simpson
W J
WJ
Department of Microbiology, University of Minnesota, Minneapolis 55455.
Musser
J M
JM
Cleary
P P
PP
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000235:genetics*; D002352:Carrier Proteins; D004269:DNA, Bacterial / Q000235:genetics; D004586:Electrophoresis; D009693:Nucleic Acid Hybridization; D015183:Restriction Mapping; D013291:Streptococcus / Q000235:genetics*; D013297:Streptococcus pyogenes / Q000235:genetics*; D014162:Transfection
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; C014689:streptococcal M protein