3god
From Proteopedia
Structural basis for DNase activity of a conserved protein implicated in CRISPR-mediated antiviral defense
Structural highlights
Function[CAS1_PSEAB] 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). Involved in the integration of spacer DNA into the CRISPR cassette (By similarity). Acts as a ss- and dsDNA-specific endonuclease.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedAcquired immunity in prokaryotes is achieved by integrating short fragments of foreign nucleic acids into clustered regularly interspaced short palindromic repeats (CRISPRs). This nucleic acid-based immune system is mediated by a variable cassette of up to 45 protein families that represent distinct immune system subtypes. CRISPR-associated gene 1 (cas1) encodes the only universally conserved protein component of CRISPR immune systems, yet its function is unknown. Here we show that the Cas1 protein is a metal-dependent DNA-specific endonuclease that produces double-stranded DNA fragments of approximately 80 base pairs in length. The 2.2 A crystal structure of the Cas1 protein reveals a distinct fold and a conserved divalent metal ion-binding site. Mutation of metal ion-binding residues, chelation of metal ions, or metal-ion substitution inhibits Cas1-catalyzed DNA degradation. These results provide a foundation for understanding how Cas1 contributes to CRISPR function, perhaps as part of the machinery for processing foreign nucleic acids. Structural basis for DNase activity of a conserved protein implicated in CRISPR-mediated genome defense.,Wiedenheft B, Zhou K, Jinek M, Coyle SM, Ma W, Doudna JA Structure. 2009 Jun 10;17(6):904-12. PMID:19523907[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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