Crystal structure of Cmr2 suggests a nucleotide cyclase-related enzyme in type III CRISPR-Cas systems.
CRISPR RNAs (crRNAs) mediate sequence-specific silencing of invading viruses and plasmids in prokaryotes. The crRNA-Cmr protein complex cleaves complementary RNA. We report the crystal structure of Pyrococcus furiosus Cmr2 (Cas10), a component of this Cmr complex and the signature protein in type III CRISPR systems. The structure reveals a nucleotide cyclase domain with a set of conserved catalytic residues that associates with an unexpected deviant cyclase domain like dimeric cyclases. Additionally, two helical domains resemble the thumb domain of A-family DNA polymerase and Cmr5, respectively. Our results suggest that Cmr2 possesses novel enzymatic activity that remains to be elucidated.
College of Life Sciences, Beijing Normal University, Beijing 100875, China.
SourceFEBS letters 586:6 2012 Mar 23 pg 939-45
MeSHAmino Acid Sequence
Molecular Sequence Data
Protein Structure, Tertiary
Pub Type(s)Journal Article
Research Support, Non-U.S. Gov't