Structural basis for promiscuous PAM recognition in type I-E Cascade from E. coli.

ABSTRACT: Clustered regularly interspaced short palindromic repeats (CRISPRs) and the cas (CRISPR-associated) operon form an RNA-based adaptive immune system against foreign genetic elements in prokaryotes. Type I accounts for 95% of CRISPR systems, and has been used to control gene expression and cell fate. During CRISPR RNA (crRNA)-guided interference, Cascade (CRISPR-associated complex for antiviral defence) facilitates the crRNA-guided invasion of double-stranded DNA for complementary base-pairing with the target DNA strand while displacing the non-target strand, forming an R-loop. Cas3, which has nuclease and helicase activities, is subsequently recruited to degrade two DNA strands. A protospacer adjacent motif (PAM) sequence flanking target DNA is crucial for self versus foreign discrimination

SUBMITTER: Hayes RP 

PROVIDER: S-EPMC5134256 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature