Structural basis for self-cleavage prevention by tag:anti-tag pairing complementarity in type VI Cas13 CRISPR systems.

ABSTRACT: Bacteria and archaea apply CRISPR-Cas surveillance complexes to defend against foreign invaders. These invading genetic elements are captured and integrated into the CRISPR array as spacer elements, guiding sequence-specific DNA/RNA targeting and cleavage. Recently, in vivo studies have shown that target RNAs with extended complementarity with repeat sequences flanking the target element (tag:anti-tag pairing) can dramatically reduce RNA cleavage by the type VI-A Cas13a system. Here, we report the cryo-EM structure of Leptotrichia shahii LshCas13a^crRNA in complex with target RNA harboring tag:anti-tag pairing complementarity, with the observed conformational changes providing a molecular explanation for inactivation of the composite HEPN domain cleavage activity. These structura

SUBMITTER: Wang B 

PROVIDER: S-EPMC8274241 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature