Structure and Activity of the RNA-Targeting Type III-B CRISPR-Cas Complex of Thermus thermophilus
- Staals, Raymond HJ;
- Agari, Yoshihiro;
- Maki-Yonekura, Saori;
- Zhu, Yifan;
- Taylor, David W;
- van Duijn, Esther;
- Barendregt, Arjan;
- Vlot, Marnix;
- Koehorst, Jasper J;
- Sakamoto, Keiko;
- Masuda, Akiko;
- Dohmae, Naoshi;
- Schaap, Peter J;
- Doudna, Jennifer A;
- Heck, Albert JR;
- Yonekura, Koji;
- van der Oost, John;
- Shinkai, Akeo
- et al.
Published Web Location
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4006948/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.
Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.