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    Cryo-EM structure of a relaxase reveals the molecular basis of DNA unwinding during bacterial conjugation

    Ilangovan, A. and Kay, C.W.M. and Roier, S. and El Mkami, H. and Salvadori, E. and Zechner, E.L. and Zanetti, Giulia and Waksman, Gabriel (2017) Cryo-EM structure of a relaxase reveals the molecular basis of DNA unwinding during bacterial conjugation. Cell 169 (4), 708-721.e12. ISSN 0092-8674.

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    Relaxases play essential roles in conjugation, the main process by which bacteria exchange genetic material, notably antibiotic resistance genes. They are bifunctional enzymes containing a trans-esterase activity, which is responsible for nicking the DNA strand to be transferred and for covalent attachment to the resulting 5′-phosphate end, and a helicase activity, which is responsible for unwinding the DNA while it is being transported to a recipient cell. Here we show that these two activities are carried out by two conformers that can both load simultaneously on the origin of transfer DNA. We solve the structure of one of these conformers by cryo electron microscopy to near-atomic resolution, elucidating the molecular basis of helicase function by relaxases and revealing insights into the mechanistic events taking place in the cell prior to substrate transport during conjugation.


    Item Type: Article
    Keyword(s) / Subject(s): relaxase, TraI, bacterial conjugation, cryo-electron microscopy, type IV secretion system, structural biology
    School: Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences
    Depositing User: Administrator
    Date Deposited: 08 May 2017 15:15
    Last Modified: 02 Aug 2023 17:32


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