3ur3

Publication Abstract from PubMed

Cmr2 is the largest and an essential subunit of a CRISPR RNA-Cas protein complex (the Cmr complex) that cleaves foreign RNA to protect prokaryotes from invading genetic elements. Cmr2 is thought to be the catalytic subunit of the effector complex because of its N-terminal HD nuclease domain. Here, however, we report that the HD domain of Cmr2 is not required for cleavage by the complex in vitro. The 2.3A crystal structure of Pyrococcus furiosus Cmr2 (lacking the HD domain) reveals two adenylyl cyclase-like and two alpha-helical domains. The adenylyl cyclase-like domains are arranged as in homodimeric adenylyl cyclases and bind ADP and divalent metals. However, mutagenesis studies show that the metal- and ADP-coordinating residues of Cmr2 are also not critical for cleavage by the complex. Our findings suggest that another component provides the catalytic function and that the essential role by Cmr2 does not require the identified ADP- or metal-binding or HD domains in vitro.

Structure of the Cmr2 Subunit of the CRISPR-Cas RNA Silencing Complex.,Cocozaki AI, Ramia NF, Shao Y, Hale CR, Terns RM, Terns MP, Li H Structure. 2012 Mar 7;20(3):545-53. PMID:22405013^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.