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

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-cOA 4 complex revealing the allosteric activation of its RNase activity. SisCsx1 is a hexamer...