CRISPR-Associated Factor Csa3b Regulates CRISPR Adaptation and Cmr-Mediated RNA Interference in Sulfolobus islandicus.

ABSTRACT: Acquisition of spacers confers the CRISPR-Cas system with the memory to defend against invading mobile genetic elements. We previously reported that the CRISPR-associated factor Csa3a triggers CRISPR adaptation in Sulfolobus islandicus. However, a feedback regulation of CRISPR adaptation remains unclear. Here we show that another CRISPR-associated factor, Csa3b, binds a cyclic oligoadenylate (cOA) analog (5'-CAAAA-3') and mutation at its CARF domain, which reduces the binding affinity. Csa3b also binds the promoter of adaptation cas genes, and the cOA analog enhances their binding probably by allosteric regulation. Deletion of the csa3b gene triggers spacer acquisition from both plasmid and viral DNAs, indicating that Csa3b acted as a repressor for CRISPR adaptation. M

SUBMITTER: Ye Q 

PROVIDER: S-EPMC7480081 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature