Allosteric regulation of Csx1, a type IIIB-associated CARF domain ribonuclease by RNAs carrying a tetraadenylate tail.

ABSTRACT: CRISPR-Cas systems protect prokaryotes against invading viruses and plasmids. The system is associated with a large number of Cas accessory proteins among which many contain a CARF (CRISPR-associated Rossmann fold) domain implicated in ligand binding and a HEPN (higher eukaryotes and prokaryotes nucleotide-binding) nuclease domain. Here, such a dual domain protein, i.e. the Sulfolobus islandicus Csx1 (SisCsx1) was characterized. The enzyme exhibited metal-independent single-strand specific ribonuclease activity. In fact, SisCsx1 showed a basal RNase activity in the absence of ligand; upon the binding of an RNA ligand carrying four continuous adenosines at the 3'-end (3'-tetra-rA), the activated SisCsx1 degraded RNA substrate with a much higher turnover rate. Amino acid substitution mutants

SUBMITTER: Han W 

PROVIDER: S-EPMC5737841 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature