5b7i
Cas3-AcrF3 complex
Structural highlights
FunctionCAS3_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). Cas3 plus Cascade participate in CRISPR interference, the third stage of CRISPR immunity (Potential). In this bacteria Y.pestis-subtype CRISPRs do not confer resistance to phage DSM3 or MP22, but instead are required for DMS3-dependent inhibition of biofilm formation and possibly motility.[1] Publication Abstract from PubMedBacteriophages express proteins that inactivate the CRISPR-Cas bacterial immune system. Here we report the crystal structure of the anti-CRISPR protein AcrF3 in complex with Pseudomonas aeruginosa Cas3 (PaCas3). AcrF3 forms a homodimer that locks PaCas3 in an ADP-bound form, blocks the entrance of the DNA-binding tunnel in the helicase domain, and masks the linker region and C-terminal domain of PaCas3, thereby preventing recruitment by Cascade and inhibiting the type I-F CRISPR-Cas system. Structural basis of Cas3 inhibition by the bacteriophage protein AcrF3.,Wang X, Yao D, Xu JG, Li AR, Xu J, Fu P, Zhou Y, Zhu Y Nat Struct Mol Biol. 2016 Jul 25. doi: 10.1038/nsmb.3269. PMID:27455460[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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