TableEdit

Nam, KH, Haitjema, C, Liu, X, Ding, F, Wang, H, DeLisa, MP and Ke, A (2012) Cas5d protein processes pre-crRNA and assembles into a cascade-like interference complex in subtype I-C/Dvulg CRISPR-Cas system. Structure 20:1574-84

Clustered regularly interspaced short palindromic repeats (CRISPRs), together with an operon of CRISPR-associated (Cas) proteins, form an RNA-based prokaryotic immune system against exogenous genetic elements. Cas5 family proteins are found in several type I CRISPR-Cas systems. Here, we report the molecular function of subtype I-C/Dvulg Cas5d from Bacillus halodurans. We show that Cas5d cleaves pre-crRNA into unit length by recognizing both the hairpin structure and the 3' single stranded sequence in the CRISPR repeat region. Cas5d structure reveals a ferredoxin domain-based architecture and a catalytic triad formed by Y46, K116, and H117 residues. We further show that after pre-crRNA processing, Cas5d assembles with crRNA, Csd1, and Csd2 proteins to form a multi-sub-unit interference complex similar to Escherichia coli Cascade (CRISPR-associated complex for antiviral defense) in architecture. Our results suggest that formation of a crRNA-presenting Cascade-like complex is likely a common theme among type I CRISPR subtypes.

PubMed PMC3479641 Online version:10.1016/j.str.2012.06.016

Bacillus; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Base Sequence; Catalytic Domain; Consensus Sequence; Crystallography, X-Ray; Endoribonucleases/chemistry; Endoribonucleases/genetics; Escherichia coli; Genetic Complementation Test; Genetic Loci; Inverted Repeat Sequences; Models, Molecular; Protein Multimerization; Protein Structure, Secondary; Protein Subunits/chemistry; RNA Cleavage; RNA Processing, Post-Transcriptional; RNA, Bacterial/chemistry; Substrate Specificity; Surface Properties