Structural mechanisms for the recruitment of factor H by <i>Streptococcus pyogenes</i>.

ABSTRACT: The major bacterial pathogen Streptococcus pyogenes (Group A Streptococcus, or Strep A) recruits the negative regulator of the alternative complement pathway factor H (FH) to its surface. Antigenically sequence variable regions of several Strep A M proteins, including M5 and M6, bind FH but have no obvious sequence homology. A second Strep A surface-localized protein, FbaA, binds FH through a purported coiled-coil region, suggesting mimicry of the well-known coiled coil of M proteins. We determined the structures of fragments of M5 protein, M6 protein, and FbaA complexed with FH domains 6 and 7 (FH(6-7)). M5 and M6 proteins formed dimeric α-helical coiled coils, as expected, while FbaA instead consisted of a monomeric three-helix bundle preceded by a loop. FH(6-7) accommodate

SUBMITTER: Kumar A 

PROVIDER: S-EPMC12340840 | biostudies-literature | 2025 Aug

REPOSITORIES: biostudies-literature