We are investigating how protein bacteriocins import their toxic payload across the Gram-negative cell envelope, both as a means of understanding the translocation process itself and as a means of probing the organization of the cell envelope and the function of the protein machines within it. Our work focuses on the import mechanism of the group A endonuclease (DNase) colicin ColE9 into Escherichia coli, where we combine in vivo observations with structural, biochemical and biophysical approaches to dissect the molecular mechanism of colicin entry. ColE9 assembles a multiprotein ‘translocon’ complex at the E. coli outer membrane that triggers entry of the toxin across the outer membrane and the simultaneous jettisoning of its tightly bound immunity protein, Im9, in a step that is dependent on the protonmotive force. In the present paper, we focus on recent work where we have uncovered how ColE9 assembles its translocon complex, including isolation of the complex, and how this leads to subversion of a signal intrinsic to the Tol–Pal assembly within the periplasm and inner membrane. In this way, the externally located ColE9 is able to ‘connect’ to the inner membrane protonmotive force via a network of protein–protein interactions that spans the entirety of the E. coli cell envelope to drive dissociation of Im9 and initiate entry of the colicin into the cell.
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December 2012
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Conference Article|
November 21 2012
Colicin translocation across the Escherichia coli outer membrane
Nicholas G. Housden;
Nicholas G. Housden
1Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K.
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Colin Kleanthous
Colin Kleanthous
1
1Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K.
1To whom correspondence should be addressed (emailcolin.kleanthous@bioch.ox.ac.uk).
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Publisher: Portland Press Ltd
Received:
September 25 2012
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2012 The Authors Journal
2012
Biochem Soc Trans (2012) 40 (6): 1475–1479.
Article history
Received:
September 25 2012
Citation
Nicholas G. Housden, Colin Kleanthous; Colicin translocation across the Escherichia coli outer membrane. Biochem Soc Trans 1 December 2012; 40 (6): 1475–1479. doi: https://doi.org/10.1042/BST20120255
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