| Literature DB >> 24119403 |
Raymond H J Staals1, Yoshihiro Agari2, Saori Maki-Yonekura2, Yifan Zhu1, David W Taylor3,4, Esther van Duijn5, Arjan Barendregt5, Marnix Vlot1, Jasper J Koehorst6, Keiko Sakamoto2, Akiko Masuda7, Naoshi Dohmae7, Peter J Schaap6, Jennifer A Doudna4,8, Albert J R Heck5, Koji Yonekura2, John van der Oost1, Akeo Shinkai2.
Abstract
The CRISPR-Cas system is a prokaryotic host defense system against genetic elements. The Type III-B CRISPR-Cas system of the bacterium Thermus thermophilus, the TtCmr complex, is composed of six different protein subunits (Cmr1-6) and one crRNA with a stoichiometry of Cmr112131445361:crRNA1. The TtCmr complex copurifies with crRNA species of 40 and 46 nt, originating from a distinct subset of CRISPR loci and spacers. The TtCmr complex cleaves the target RNA at multiple sites with 6 nt intervals via a 5' ruler mechanism. Electron microscopy revealed that the structure of TtCmr resembles a "sea worm" and is composed of a Cmr2-3 heterodimer "tail," a helical backbone of Cmr4 subunits capped by Cmr5 subunits, and a curled "head" containing Cmr1 and Cmr6. Despite having a backbone of only four Cmr4 subunits and being both longer and narrower, the overall architecture of TtCmr resembles that of Type I Cascade complexes.Entities:
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Year: 2013 PMID： 24119403 PMCID： PMC4006948 DOI： 10.1016/j.molcel.2013.09.013
Source DB: PubMed Journal: Mol Cell ISSN： 1097-2765 Impact factor: 17.970