Slipped-strand mispairing within a polycytidine tract in transcriptional regulator mga leads to M protein phase variation and Mga length polymorphism in Group A Streptococcus.

ABSTRACT: The M protein, a major virulence factor of Group A Streptococcus (GAS), is regulated by the multigene regulator Mga. An unexplained phenomena frequently occurring with in vitro genetic manipulation or culturing of M1T1 GAS strains is the loss of M protein production. This study was aimed at elucidating the basis for the loss of M protein production. The majority of M protein-negative (M^-) variants had one C deletion at a tract of 8 cytidines starting at base 1,571 of the M1 mga gene, which is designated as c.1571C[8]. The C deletion led to a c.1571C[7] mga variant that has an open reading frame shift and encodes a Mga-M protein fusion protein. Transformation with a plasmid containing wild-type mga restored the production of the M protein in the c.1571

SUBMITTER: Lei B 

PROVIDER: S-EPMC10330708 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature