Abstract
Cas9 is an RNA-guided DNA endonuclease and is implicated in the bacterial CRISPR-Cas adaptive immune system. Cas9 binds dual guide RNAs or single-guide RNA, and the Cas9-RNA complex recognizes and cleaves target double-stranded DNA via RNA-DNA complementarity. To understand this unprecedented, RNA-guided DNA cleavage mechanism, we solved the crystal structure of Cas9 in complex with guide RNA and target DNA. The ternary complex structure provides insights into the RNA-guided DNA cleavage mechanism, and paves the way for the rational design of new, Cas9-based tools.
