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Nature. 2016 Oct 13;538(7624):270-273. doi: 10.1038/nature19802. Epub 2016 Sep 26.

Two distinct RNase activities of CRISPR-C2c2 enable guide-RNA processing and RNA detection.

Author information

1
Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.
2
Department of Chemistry, University of California, Berkeley, California 94720, USA.
3
Department of Earth And Planetary Sciences, University of California, Berkeley, California 94720, USA.
4
MBIB Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
5
Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, USA.
6
Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA.
7
Li Ka Shing Biomedical and Health Sciences Center, University of California, Berkeley, California 94720, USA.
8
Innovative Genomics Initiative, University of California, Berkeley, California 94720, USA.

Abstract

Bacterial adaptive immune systems use CRISPRs (clustered regularly interspaced short palindromic repeats) and CRISPR-associated (Cas) proteins for RNA-guided nucleic acid cleavage. Although most prokaryotic adaptive immune systems generally target DNA substrates, type III and VI CRISPR systems direct interference complexes against single-stranded RNA substrates. In type VI systems, the single-subunit C2c2 protein functions as an RNA-guided RNA endonuclease (RNase). How this enzyme acquires mature CRISPR RNAs (crRNAs) that are essential for immune surveillance and how it carries out crRNA-mediated RNA cleavage remain unclear. Here we show that bacterial C2c2 possesses a unique RNase activity responsible for CRISPR RNA maturation that is distinct from its RNA-activated single-stranded RNA degradation activity. These dual RNase functions are chemically and mechanistically different from each other and from the crRNA-processing behaviour of the evolutionarily unrelated CRISPR enzyme Cpf1 (ref. 11). The two RNase activities of C2c2 enable multiplexed processing and loading of guide RNAs that in turn allow sensitive detection of cellular transcripts.

PMID:
27669025
PMCID:
PMC5576363
DOI:
10.1038/nature19802
[Indexed for MEDLINE]
Free PMC Article

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