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4qts

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

Structural highlights

4qts is a 4 chain structure with sequence from Methanocaldococcus jannaschii DSM 2661. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 3.105Å
Ligands:
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

CSM4_METJA CRISPR (clustered regularly interspaced short palindromic repeat) is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain spacers, sequences complementary to antecedent mobile elements, and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA) (By similarity).

Publication Abstract from PubMed

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 3.1A 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.

Crystal Structure of the Csm3-Csm4 Subcomplex in the Type III-A CRISPR-Cas Interference Complex.,Numata T, Inanaga H, Sato C, Osawa T J Mol Biol. 2014 Oct 30. pii: S0022-2836(14)00564-6. doi:, 10.1016/j.jmb.2014.09.029. PMID:25451598^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Numata T, Inanaga H, Sato C, Osawa T. Crystal Structure of the Csm3-Csm4 Subcomplex in the Type III-A CRISPR-Cas Interference Complex. J Mol Biol. 2014 Oct 30. pii: S0022-2836(14)00564-6. doi:, 10.1016/j.jmb.2014.09.029. PMID:25451598 doi:http://dx.doi.org/10.1016/j.jmb.2014.09.029