Cutting it close: CRISPR-associated endoribonuclease structure and function

• Published in: Trends in biochemical sciences (Amsterdam. Regular ed.) Vol. 40; no. 1; pp. 58 - 66
• Main Authors: Hochstrasser, Megan L., Doudna, Jennifer A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2015
• Subjects: Bacteria - genetics; Bacteria - immunology; Cas5; Cas6; CRISPR-Associated Proteins - chemistry; CRISPR-Associated Proteins - genetics; CRISPR-Associated Proteins - metabolism; CRISPR-Cas Systems - genetics; CRISPR–Cas; crRNA; endoribonuclease; Endoribonucleases - chemistry; Endoribonucleases - genetics; Endoribonucleases - metabolism; Protein Conformation; Protein Folding; RNA - chemistry; RNA - genetics; RNA Interference; structure and function; Structure-Activity Relationship; Substrate Specificity; endoribonuclease; CRISPR–Cas; structure and function; crRNA; Cas6; Cas5
• ISSN: 0968-0004; 1362-4326
• DOI: 10.1016/j.tibs.2014.10.007

•We define the key structural features shared by CRISPR-associated endoRNases.•We explain how Cas6 enzymes recognize RNA with high affinity and specificity.•We review the cleavage mechanisms of different CRISPR-associated endoribonucleases.•We describe the roles of Cas5 and Cas6 proteins in CRISPR interference complexes.•We discuss future work and development of Cas6-based biotechnological applications. Many bacteria and archaea possess an adaptive immune system consisting of repetitive genetic elements known as clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) proteins. Similar to RNAi pathways in eukaryotes, CRISPR–Cas systems require small RNAs for sequence-specific detection and degradation of complementary nucleic acids. Cas5 and Cas6 enzymes have evolved to specifically recognize and process CRISPR-derived transcripts into functional small RNAs used as guides by interference complexes. Our detailed understanding of these proteins has led to the development of several useful Cas6-based biotechnological methods. Here, we review the structures, functions, mechanisms, and applications of the enzymes responsible for CRISPR RNA (crRNA) processing, highlighting a fascinating family of endonucleases with exquisite RNA recognition and cleavage activities.