Toxic anti-phage defense proteins inhibited by intragenic antitoxin proteins.

ABSTRACT: Recombination-promoting nuclease (Rpn) proteins are broadly distributed across bacterial phyla, yet their functions remain unclear. Here we report these proteins are new toxin-antitoxin systems, comprised of genes-within-genes, that combat phage infection. We show the small, highly variable Rpn C -terminal domains (Rpn _S ), which are translated separately from the full-length proteins (Rpn _L ), directly block the activities of the toxic full-length proteins. The crystal structure of RpnA _S revealed a dimerization interface encompassing a helix that can have four amino acid repeats whose number varies widely among strains of the same species. Consistent with strong selection for the variation, we document plasmid-encoded RpnP2 _L protects

SUBMITTER: Zhong A 

PROVIDER: S-EPMC10327210 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature