Structure and Activity of the RNA-Targeting Type III-B CRISPR-Cas Complex of Thermus thermophilus

R.H.J. Staals, Y. Agari, S. Maki-Yonekura, Y. Zhu, D.W. Taylor, E. van Duijn, A. Barendregt, M.C. Vlot, J.J. Koehorst, K. Sakamoto, A. Masuda, N. Dohmae, P.J. Schaap, J.A. Doudna, A.J.R. Heck, K. Yonekura, J. van der Oost, A. Shinkai

Research output: Contribution to journalArticleAcademicpeer-review


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.
Original languageEnglish
Pages (from-to)135-145
Number of pages11
JournalMolecular Cell
Issue number1
Publication statusPublished - 2013


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