Structure of Csx1-cOA₄ complex reveals the basis of RNA decay in Type III-B CRISPR-Cas.

ABSTRACT: Type III CRISPR-Cas multisubunit complexes cleave ssRNA and ssDNA. These activities promote the generation of cyclic oligoadenylate (cOA), which activates associated CRISPR-Cas RNases from the Csm/Csx families, triggering a massive RNA decay to provide immunity from genetic invaders. Here we present the structure of Sulfolobus islandicus (Sis) Csx1-cOA₄ complex revealing the allosteric activation of its RNase activity. SisCsx1 is a hexamer built by a trimer of dimers. Each dimer forms a cOA₄ binding site and a ssRNA catalytic pocket. cOA₄ undergoes a conformational change upon binding in the second messenger binding site activating ssRNA degradation in the catalytic pockets. Activation is transmitted in an allosteric manner through an intermediate HTH domai

SUBMITTER: Molina R 

PROVIDER: S-EPMC6754442 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature