Complete nucleotide sequence of type 6 M protein of the group A Streptococcus. Repetitive structure and membrane anchor.

The DNA sequence of the gene for type 6 M protein of Streptococcus pyogenes contains two extended tandem repeat regions and one nontandem repeat region. We suggest that the duplication and deletion of these repeats generates the observed diversity in size and sequence among the family of M proteins in the group A streptococci. In addition, the DNA sequence reveals the presence of a 42-amino-acid signal peptide, a region rich in proline that is thought to be located in the cell wall, and a membrane anchor sequence at the carboxyl-terminal end of the protein. Signals similar to the consensus sequences recognized for the initiation of transcription and translation in Gram-positive bacteria have been identified in the DNA sequence. Codon usage is similar to that of other Gram-positive bacteria and significantly different from that of Escherichia coli.