Crystal structure of the Csm3-Csm4 subcomplex in the type III-A CRISPR-Cas interference complex

Tomoyuki Numata, Hideko Inanaga, Chikara Sato, Takuo Osawa

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Clustered, regularly interspaced, short palindromic repeat (CRISPR) loci play a pivotal role in the prokaryotic host defense system against invading genetic materials. The CRISPR loci are transcribed to produce CRISPR RNAs (crRNAs), which form interference complexes with CRISPR-associated (Cas) proteins to target the invading nucleic acid for degradation. The interference complex of the type III-A CRISPR-Cas system is composed of five Cas proteins (Csm1-Csm5) and a crRNA, and targets invading DNA. Here, we show that the Csm1, Csm3, and Csm4 proteins from Methanocaldococcus jannaschii form a stable subcomplex. We also report the crystal structure of the M. jannaschii Csm3-Csm4 subcomplex at 3.1 A˚ resolution. The complex structure revealed the presence of a basic concave surface around their interface, suggesting the RNA and/or DNA binding ability of the complex. A gel retardation analysis showed that the Csm3-Csm4 complex binds single-stranded RNA in a non-sequence-specific manner. Csm4 structurally resembles Cmr3, a component of the type III-B CRISPR-Cas interference complex. Based on bioinformatics, we constructed a model structure of the Csm1-Csm4-Csm3 ternary complex, which provides insights into its role in the Csm interference complex.

Original languageEnglish
Pages (from-to)259-273
Number of pages15
JournalJournal of Molecular Biology
Volume427
Issue number2
DOIs
Publication statusPublished - Jan 30 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

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