9p11

Cas1-Cas2/3 integrase, heterohexameric assembly

spinqualitylabelsall models 9p11, resolution 3.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9p11 is a 6 chain structure with sequence from Pseudomonas aeruginosa. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.5Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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. Publication Abstract from PubMed Cas1 and Cas2 are the hallmark proteins of prokaryotic adaptive immunity. However, these two proteins are often fused to other proteins and the functional association of these fusions often remain poorly understood. Here we purify and determine structures of Cas1 and the Cas2/3 fusion proteins from Pseudomonas aeruginosa at distinct stages of CRISPR adaptation. Collectively, these structures reveal a prominent, positively charged channel on one face of the integration complex that captures short fragments of foreign DNA. Foreign DNA binding triggers conformational changes in Cas2/3 that expose new DNA binding surfaces necessary for homing the DNA-bound integrase to specific CRISPR loci. The length of the foreign DNA substrate determines if Cas1-2/3 docks completely onto the CRISPR repeat to successfully catalyze two sequential transesterification reactions required for integration. Together, these structures clarify how the Cas1-2/3 proteins orchestrate foreign DNA capture, site-specific delivery, and integration of new DNA into the bacterial genome. Structures reveal how the Cas1-2/3 integrase captures, delivers, and integrates foreign DNA into CRISPR loci.,Henriques WS, Bowman J, Hall LN, Gauvin CC, Wei H, Kuang H, Zimanyi CM, Eng ET, Santiago-Frangos A, Wiedenheft B Structure. 2025 Oct 9:S0969-2126(25)00350-8. doi: 10.1016/j.str.2025.09.007. PMID:41072406 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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