RNA Targeting by Functionally Orthogonal Type VI-A CRISPR-Cas Enzymes.

ABSTRACT: CRISPR adaptive immunity pathways protect prokaryotic cells against foreign nucleic acids using CRISPR RNA (crRNA)-guided nucleases. In type VI-A CRISPR-Cas systems, the signature protein Cas13a (formerly C2c2) contains two separate ribonuclease activities that catalyze crRNA maturation and ssRNA degradation. The Cas13a protein family occurs across different bacterial phyla and varies widely in both protein sequence and corresponding crRNA sequence conservation. Although grouped phylogenetically together, we show that the Cas13a enzyme family comprises two distinct functional groups that recognize orthogonal sets of crRNAs and possess different ssRNA cleavage specificities. These functional distinctions could not be bioinformatically predicted, suggesting more subtle co-evolution of Cas13a

SUBMITTER: East-Seletsky A 

PROVIDER: S-EPMC5999320 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature