7mcs
From Proteopedia
Cryo-electron microscopy structure of TnsC(1-503)A225V bound to DNA
Structural highlights
FunctionTNSC_ECOLX TnsC binds non-specifically to DNA in the presence of ATP. It is required for Tn7 transposition. TnsABC + TnsD promote high-frequency insertion of Tn7 into a specific target site known as att-Tn7 whereas TnsABC + TnsE promote low-frequency insertion into many different sites. Publication Abstract from PubMedTn7 transposable elements are unique for their highly specific, and sometimes programmable, target-site selection mechanisms and precise insertions. All the elements in the Tn7 family utilize an AAA+ adaptor (TnsC) to coordinate target-site selection with transpososome assembly and to prevent insertions at sites already containing a Tn7 element. Owing to its multiple functions, TnsC is considered the linchpin in the Tn7 element. Here we present the high-resolution cryo-EM structure of TnsC bound to DNA using a gain-of-function variant of the protein and a DNA substrate that together recapitulate the recruitment to a specific DNA target site. TnsC forms an asymmetric ring on target DNA that segregates target-site selection and interaction with the paired-end complex to opposite faces of the ring. Unlike most AAA+ ATPases, TnsC uses a DNA distortion to find the target site but does not remodel DNA to activate transposition. By recognizing pre-distorted substrates, TnsC creates a built-in regulatory mechanism where ATP hydrolysis abolishes ring formation proximal to an existing element. This work unveils how Tn7 and Tn7-like elements determine the strict spacing between the target and integration sites. Structural basis for DNA targeting by the Tn7 transposon.,Shen Y, Gomez-Blanco J, Petassi MT, Peters JE, Ortega J, Guarne A Nat Struct Mol Biol. 2022 Feb;29(2):143-151. doi: 10.1038/s41594-022-00724-8., Epub 2022 Feb 16. PMID:35173349[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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