Research Article

Structures of Cas9 Endonucleases Reveal RNA-Mediated Conformational Activation

Science  06 Feb 2014:

DOI: 10.1126/science.1247997

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Abstract

Type II CRISPR-Cas systems use an RNA-guided DNA endonuclease, Cas9, to generate double-strand breaks in invasive DNA during an adaptive bacterial immune response. Cas9 has been harnessed as a powerful tool for genome editing and gene regulation in many eukaryotic organisms. Here, we report 2.6 and 2.2 Å resolution crystal structures of two major Cas9 enzymes subtypes, revealing the structural core shared by all Cas9 family members. The architectures of Cas9 enzymes define nucleic acid binding clefts, and single-particle electron microscopy reconstructions show that the two structural lobes harboring these clefts undergo guide RNA-induced reorientation to form a central channel where DNA substrates are bound. The observation that extensive structural rearrangements occur before target DNA duplex binding implicates guide RNA loading as a key step in Cas9 activation.

  • Corresponding author. E-mail: jinek{at}bioc.uzh.ch (M.J.); enogales{at}lbl.gov (E.N.); doudna{at}berkeley.edu (J.A.D.)

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