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Mol Cell. 2014 Nov 20;56(4):518-30. doi: 10.1016/j.molcel.2014.10.005. Epub 2014 Nov 6.

RNA targeting by the type III-A CRISPR-Cas Csm complex of Thermus thermophilus.

Author information

1
Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, 6703 HB Wageningen, the Netherlands. Electronic address: raymond.staals@otago.ac.nz.
2
Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, 6703 HB Wageningen, the Netherlands.
3
Howard Hughes Medical Institute and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720-3200, USA.
4
Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
5
Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, 3584 CH Utrecht, the Netherlands.
6
Laboratory of Systems and Synthetic Biology, Wageningen University, 6703 HB Wageningen, the Netherlands.
7
RIKEN SPring-8 Center, Hyogo 679-5148, Japan.
8
Global Research Cluster, RIKEN, Saitama 351-0198, Japan.
9
Structural Biology Laboratory, RIKEN, Kanagawa 230-0045, Japan.
10
Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany; Bioanalytics Research Group, Department of Clinical Chemistry, University Medical Center, 37075 Göttingen, Germany.
11
Howard Hughes Medical Institute and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720-3200, USA; Department of Molecular and Cell Biology, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-3200, USA; Life Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA 94720-3200, USA.
12
Howard Hughes Medical Institute and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720-3200, USA; Department of Molecular and Cell Biology, Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-3200, USA; Physical Biosciences Division, Lawrence Berkeley National Lab, Berkeley, CA 94720-3200, USA.
13
RIKEN SPring-8 Center, Hyogo 679-5148, Japan; Structural Biology Laboratory, RIKEN, Kanagawa 230-0045, Japan.
14
Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, 6703 HB Wageningen, the Netherlands. Electronic address: john.vanderoost@wur.nl.

Abstract

CRISPR-Cas is a prokaryotic adaptive immune system that provides sequence-specific defense against foreign nucleic acids. Here we report the structure and function of the effector complex of the Type III-A CRISPR-Cas system of Thermus thermophilus: the Csm complex (TtCsm). TtCsm is composed of five different protein subunits (Csm1-Csm5) with an uneven stoichiometry and a single crRNA of variable size (35-53 nt). The TtCsm crRNA content is similar to the Type III-B Cmr complex, indicating that crRNAs are shared among different subtypes. A negative stain EM structure of the TtCsm complex exhibits the characteristic architecture of Type I and Type III CRISPR-associated ribonucleoprotein complexes. crRNA-protein crosslinking studies show extensive contacts between the Csm3 backbone and the bound crRNA. We show that, like TtCmr, TtCsm cleaves complementary target RNAs at multiple sites. Unlike Type I complexes, interference by TtCsm does not proceed via initial base pairing by a seed sequence.

PMID:
25457165
PMCID:
PMC4342149
DOI:
10.1016/j.molcel.2014.10.005
[Indexed for MEDLINE]
Free PMC Article

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