Cas3/I-C mediated target DNA recognition and cleavage during CRISPR interference are independent of the composition and architecture of Cascade surveillance complex.

ABSTRACT: In type I CRISPR-Cas system, Cas3-a nuclease cum helicase-in cooperation with Cascade surveillance complex cleaves the target DNA. Unlike the Cascade/I-E, which is composed of five subunits, the Cascade/I-C is made of only three subunits lacking the CRISPR RNA processing enzyme Cas6, whose role is assumed by Cas5. How these differences in the composition and organization of Cascade subunits in type I-C influence the Cas3/I-C binding and its target cleavage mechanism is poorly understood. Here, we show that Cas3/I-C is intrinsically a single-strand specific promiscuous nuclease. Apart from the helicase domain, a constellation of highly conserved residues-which are unique to type I-C-located in the uncharacterized C-terminal domain appears to influence the nuclease activity. Recruited by Cas

SUBMITTER: Nimkar S 

PROVIDER: S-EPMC7049708 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature