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

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

Author information

1
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
2
Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA.
3
Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
4
Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA. Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA. California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA. Department of Chemistry, University of California, Berkeley, CA 94720, USA. Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA. Innovative Genomics Initiative, University of California, Berkeley, CA 94720, USA. doudna@berkeley.edu.

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.

PMID:
26113724
DOI:
10.1126/science.aab1452
[Indexed for MEDLINE]

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