30ga

Cryo-EM structure of the PseCascade-TniQ-TnsC-TnsAB holocomplex

spinqualitylabelsall models 30ga, resolution 3.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 30ga is a 35 chain structure with sequence from Escherichia coli K-12 and Pseudoalteromonas sp. S983. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3.2Å Ligands: ATP, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A0ABF7PQB9_9GAMM Publication Abstract from PubMed CRISPR-associated transposases (CASTs) achieve site-specific DNA integration by coupling the RNA-guided targeting action of a nuclease-deficient CRISPR-Cas system with the assembly of a Tn7-like transpososome complex (1,2) . Understanding the detailed mechanisms of this elaborate process is paramount to engineering CAST systems into programmable genetic tools (3-6) . The type I-F Pseudoalteromonas CAST ( Pse CAST) displays the highest activity in mammalian cells to date (7) and has been the subject of extensive directed evolution (8) , but efforts to rationally engineer further improvements have been hampered by critical gaps in our understanding of transpososome assembly and activation (9) . Here we use cryo-EM structural analysis, validated by DNA transposition assays, to visualize the Pse CAST system in a series of functional states that define the stepwise mechanism of RNA-guided DNA integration. The structure of a target DNA-bound Cascade-TniQ-TnsC complex reveals that conformational changes induced by R-loop formation are coupled to target DNA stabilization and TnsC heptamerization, which in turn recruits the TnsAB transposase via conserved interactions with its C-terminal tail. Finally, the structure of the 1.2 MDa Pse CAST transpososome holocomplex reveals specific TnsC-TnsB and TnsB-target DNA interactions that drive allosteric remodelling of the TnsB catalytic site to activate donor DNA integration. Together, these findings establish a unified structural and mechanistic blueprint for RNA-guided DNA integration and lay the foundation for engineering next-generation DNA insertion systems for genome editing applications. Structural basis of RNA-guided DNA integration by type I CRISPR-associated transposases.,Finocchio G, Oberli S, Lampe G, Schmitz M, Sternberg SH, Jinek M bioRxiv [Preprint]. 2026 May 18:2026.05.18.725949. doi: , 10.64898/2026.05.18.725949. PMID:42239233 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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