SNAP output for PDB entry 4ill [SNAP web server]

PDB-id

4ill; SNAP-derived features in text and JSON formats; DNAproDB

Class

hydrolase-RNA

Method

X-ray (2.484 Å)

Summary

Recognition and cleavage of a non-structured crispr RNA by its processing endoribonuclease cas6

Reference

Shao Y, Li H (2013): "Recognition and cleavage of a nonstructured CRISPR RNA by its processing endoribonuclease Cas6." Structure, 21, 385-393. doi: 10.1016/j.str.2013.01.010.

Abstract

Clustered regularly interspaced short palindromic repeats (CRISPRs) confer adaptive immunity to prokaryotes through a small RNA-mediated mechanism. Specific endoribonucleases are required by all CRISPR-bearing organisms to process CRISPR RNAs into small RNA that serve as guides for defensive effector complexes. The molecular mechanism of how the endoribonucleases process the class of CRISPR RNA containing no predicted secondary structural features remains largely elusive. Here, we report cocrystal structures of a processing endoribonuclease bound with a noncleavable RNA substrate and its product-like fragment derived from a nonpalindramic repeat. The enzyme stabilizes a short RNA stem-loop structure near the cleavage site and cleaves the phosphodiester bond using an active site comprised of arginine and lysine residues. The distinct RNA binding and cleavage mechanisms underline the diversity in CRISPR RNA processing.