Structure and mechanism of a Type III CRISPR defence DNA nuclease activated by cyclic oligoadenylate

Abstract

Antiviral defence type III CRISPR systems produce cyclic oligoadenylates (cOA) as second messengers that activate downstream effectors. Here the authors present the crystal structure of the type III CRISPR defence DNA nuclease Can1 in complex with cyclic tetra-adenylate (cA4) and show that Can1 nicks supercoiled DNA.