PMID: 26113724 , Related PDB ids: 4ZT0, 4ZT9

Authors:

Jiang F, Zhou K, Ma L, Gressel S, Doudna JA

Title:

STRUCTURAL BIOLOGY. A Cas9-guide RNA complex preorganized for target DNA recognition.

Journal:

Science. 2015 Jun 26;348(6242):1477-81. doi: 10.1126/science.aab1452.

Abstract:

Bacterial adaptive immunity uses CRISPR (clustered regularly interspaced short palindromic repeats)-associated (Cas) proteins together with CRISPR transcripts for foreign DNA degradation. In type II CRISPR-Cas systems, activation of Cas9 endonuclease for DNA recognition upon guide RNA binding occurs by an unknown mechanism. Crystal structures of Cas9 bound to single-guide RNA reveal a conformation distinct from both the apo and DNA-bound states, in which the 10-nucleotide RNA "seed" sequence required for initial DNA interrogation is preordered in an A-form conformation. This segment of the guide RNA is essential for Cas9 to form a DNA recognition-competent structure that is poised to engage double-stranded DNA target sequences. We construe this as convergent evolution of a "seed" mechanism reminiscent of that used by Argonaute proteins during RNA interference in eukaryotes.