| Literature DB >> 25457165 |
Raymond H J Staals1, Yifan Zhu2, David W Taylor3, Jack E Kornfeld3, Kundan Sharma4, Arjan Barendregt5, Jasper J Koehorst6, Marnix Vlot2, Nirajan Neupane2, Koen Varossieau2, Keiko Sakamoto7, Takehiro Suzuki8, Naoshi Dohmae8, Shigeyuki Yokoyama9, Peter J Schaap6, Henning Urlaub10, Albert J R Heck5, Eva Nogales11, Jennifer A Doudna12, Akeo Shinkai13, John van der Oost14.
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.Entities:
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Year: 2014 PMID： 25457165 PMCID： PMC4342149 DOI： 10.1016/j.molcel.2014.10.005
Source DB: PubMed Journal: Mol Cell ISSN： 1097-2765 Impact factor: 17.970