5g4d

From Proteopedia

Crystal structure of the Cas2 in T.onnurineus

Structural highlights

5g4d is a 1 chain structure with sequence from Thermococcus onnurineus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 1.701Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

B6YTB8_THEON 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 sequences complementary to antecedent mobile elements and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). Functions as a ssRNA-specific endoribonuclease. Involved in the integration of spacer DNA into the CRISPR cassette.[HAMAP-Rule:MF_01471]

Publication Abstract from PubMed

CRISPR-Cas is RNA-based prokaryotic immune systems that defend against exogenous genetic elements such as plasmids and viruses. Cas1 and Cas2 are highly conserved components that play an essential part in the adaptation stage of all CRISPR-Cas systems. Characterization of CRISPR-Cas genes in Thermococcus onnurineus reveals the association of the Cas2 gene with the putative type IV system that lacks Cas1 or its homologous genes. Here, we present a crystal structure of T. onnurineus Cas2 (Ton_Cas2) that exhibits a deep and wide cleft at an interface lined with positive residues (Arg16, Lys18, Lys19, Arg22, and Arg23). The obvious DNA recognizing loops in Cas2 from E. coli (Eco_Cas2) are absent in Ton_Cas2 and have significantly different shapes and electrostatic potential distributions around the putative nucleotide binding region. Furthermore, Ton_Cas2 lacks the hairpin motif at the C-terminus that is responsible for Cas1 binding in Eco_Cas2. These structural features could be a unique signature and indicate an altered functional mechanism in the adaptation stage of Cas2 in type IV CRISPR-Cas systems.

Structural features of Cas2 from Thermococcus onnurineus in CRISPR-cas system type IV.,Jung TY, Park KH, An Y, Schulga A, Deyev S, Jung JH, Woo EJ Protein Sci. 2016 Jul 12. doi: 10.1002/pro.2981. PMID:27400737^[1]

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

References

↑ Jung TY, Park KH, An Y, Schulga A, Deyev S, Jung JH, Woo EJ. Structural features of Cas2 from Thermococcus onnurineus in CRISPR-cas system type IV. Protein Sci. 2016 Jul 12. doi: 10.1002/pro.2981. PMID:27400737 doi:http://dx.doi.org/10.1002/pro.2981