title: Cas5d protein processes pre-crRNA and assembles into a cascade-like interference complex in subtype I-C/Dvulg CRISPR-Cas system.
abstract: 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.
authors: Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
authors: Ki Hyun
authors: KH
authors: Nam
authors: Charles
authors: C
authors: Haitjema
authors: Xueqi
authors: X
authors: Liu
authors: Fran
authors: F
authors: Ding
authors: Hongwei
authors: H
authors: Wang
authors: Matthew P
authors: MP
authors: DeLisa
authors: Ailong
authors: A
authors: Ke
mesh_terms: D001407:Bacillus; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D001483:Base Sequence; D020134:Catalytic Domain; D016384:Consensus Sequence; D018360:Crystallography, X-Ray; D004722:Endoribonucleases / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli; D005816:Genetic Complementation Test; D056426:Genetic Loci; D055029:Inverted Repeat Sequences; D008958:Models, Molecular; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry; D059367:RNA Cleavage; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000737:chemistry*; D013379:Substrate Specificity; D013499:Surface Properties
chemical_list: D001426:Bacterial Proteins; D021122:Protein Subunits; D012329:RNA, Bacterial; D004722:Endoribonucleases