Related Experiment Video
Updated: May 23, 2026

Substrate Generation for Endonucleases of CRISPR/Cas Systems
Published on: September 8, 2012
Crystal structure of Cmr2 suggests a nucleotide cyclase-related enzyme in type III CRISPR-Cas systems
1College of Life Sciences, Beijing Normal University, Beijing 100875, China.
Abstract:
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.
Related Concept Videos
CRISPR and crRNAs
The CRISPR-Cas system stores a copy of foreign DNA in the host genome and uses it to identify the foreign DNA upon reinfection. CRISPR-Cas has three different...
CRISPR
CRISPR
The Antiviral System of Bacteria and Archaea: CRISPR
CRISPR/Cas9 Genome Editing
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...

