Antigenic diversity within a family of M proteins from group A streptococci: evidence for the role of frameshift and compensatory mutations

• Published in: Gene Vol. 144; no. 1; pp. 25 - 30
• Main Authors: Relf, Wendy A., Martin, Diana R., Sriprakash, Kadaba S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 24.06.1994
• Subjects: Amino Acid Sequence; antigenic variation; Antigens, Bacterial - genetics; Antigens, Bacterial - immunology; Bacterial Outer Membrane Proteins; Bacterial Proteins - genetics; Bacterial Proteins - immunology; Base Sequence; Carrier Proteins; DNA, Bacterial; Epitopes - genetics; Frameshift Mutation; Molecular Sequence Data; Sequence Homology, Amino Acid; Sequence Homology, Nucleic Acid; Streptococcus pyogenes; Streptococcus pyogenes - genetics; Streptococcus pyogenes - immunology; aa; ST; antigenic variation; emm; nt; emmL; molecular sequence data; bp; MNT; kb; GAS; Streptococcus pyogenes; ML
• ISSN: 0378-1119; 1879-0038
• DOI: 10.1016/0378-1119(94)90198-8

The genes ( emm) encoding M proteins, from isolates of group-A streptococci (GAS) serotyped as M52, M53, M80 and M nontypeable (MNT; serologically related to M53 and M80), were examined. Characterization of emm from these GAS revealed some discrepancies with serotyping, illustrating the difficulty in serotype determination when cross-reactions occur. DNA sequences corresponding to the N-terminal region of M proteins from the isolates showed considerable similarity both in the hypervariable region and the repeat regions. We propose that these serotypes form a family of closely related M types. Frameshift mutations in the hypervariable region followed by a corrective (compensatory) frameshift were observed. This may be an effective mechanism for generating antigenic diversity in the M protein.