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The cytotoxic domain of colicin E9 is a channel-forming endonuclease

Mosbahi, Khédidja, Lemaître, Christelle, Mobasheri, Hamid, Morel, Bertrand, Lea, Edward J.A., Kleanthous, Colin, Keeble, Anthony H., James, Richard and Moore, Geoffrey R. (2002) The cytotoxic domain of colicin E9 is a channel-forming endonuclease. Nature Structural Biology. pp. 476-484. ISSN 1545-9985

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Bacterial toxins commonly translocate cytotoxic enzymes into cells using dedicated channelforming subunits or domains as conduits. We demonstrate that the small cytotoxic endonuclease domain from the bacterial toxin colicin E9 (the E9 DNase) exhibits nonvoltage- gated, channel-forming activity in planar lipid bilayers and that this activity is linked to toxin translocation into cells. A disulfide bond engineered into the DNase abolished channel activity and colicin toxicity but left endonuclease activity unaffected, with NMR experiments suggesting decreased conformational flexibility as the likely reason for these alterations. Concomitant with the reduction of the disulfide bond was the restoration of conformational flexibility, DNase channel activity and colicin toxicity. Our data suggest that endonuclease domains of colicins may mediate their own translocation across the bacterial inner membrane through an intrinsic channel activity that is dependent on structural plasticity in the protein.

Item Type: Article
Copyright, Publisher and Additional Information: Copyright © 2002 Nature Publishing Group. This is an author produced version of an article published in Nature Structural Biology. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.
Institution: The University of York
Academic Units: The University of York > Biology (York)
Depositing User: Christina Hudson
Date Deposited: 23 Feb 2006
Last Modified: 05 Apr 2016 13:45
Published Version: http://dx.doi.org/10.1038/nsb797
Status: Published
Refereed: Yes
URI: http://eprints.whiterose.ac.uk/id/eprint/1066

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