Structural basis of cyclic oligoadenylate degradation by ancillary Type III CRISPR-Cas ring nucleases.

ABSTRACT: Type III CRISPR-Cas effector systems detect foreign RNA triggering DNA and RNA cleavage and synthesizing cyclic oligoadenylate molecules (cA) in their Cas10 subunit. cAs act as a second messenger activating auxiliary nucleases, leading to an indiscriminate RNA degradation that can end in cell dormancy or death. Standalone ring nucleases are CRISPR ancillary proteins which downregulate the strong immune response of Type III systems by degrading cA. These enzymes contain a CRISPR-associated Rossman-fold (CARF) domain, which binds and cleaves the cA molecule. Here, we present the structures of the standalone ring nuclease from Sulfolobus islandicus (Sis) 0811 in its apo and post-catalytic states. This enzyme is composed by a N-terminal CARF and a C-terminal wHTH domain. Sis0811 presents a pho

SUBMITTER: Molina R 

PROVIDER: S-EPMC8643638 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature