Spacer capture and integration by a type I-F Cas1-Cas2-3 CRISPR adaptation complex.

ABSTRACT: CRISPR-Cas adaptive immune systems capture DNA fragments from invading bacteriophages and plasmids and integrate them as spacers into bacterial CRISPR arrays. In type I-E and II-A CRISPR-Cas systems, this adaptation process is driven by Cas1-Cas2 complexes. Type I-F systems, however, contain a unique fusion of Cas2, with the type I effector helicase and nuclease for invader destruction, Cas3. By using biochemical, structural, and biophysical methods, we present a structural model of the 400-kDa Cas1₄-Cas2-3₂ complex from Pectobacterium atrosepticum with bound protospacer substrate DNA. Two Cas1 dimers assemble on a Cas2 domain dimeric core, which is flanked by two Cas3 domains forming a groove where the protospacer binds to Cas1-Cas2. We developed a sensitive i

SUBMITTER: Fagerlund RD 

PROVIDER: S-EPMC5495228 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature