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Energy landscape steering in SecYEG mediates dynamic coupling in ATP driven protein translocation

By Joel A. Crossley, Tomas Fessl, Matthew A. Watson, Daniel W. Watkins, Robin A. Corey, William J. Allen, Tara Sabir, Sheena E. Radford, Ian Collinson, Roman Tuma

Posted 05 Oct 2019
bioRxiv DOI: 10.1101/793943

The Sec translocon is a transmembrane assembly highly conserved among all forms of life as the principal route for transport of polypeptides across or into lipid bilayers. In bacteria translocation involves allosteric communication between the membrane pore SecYEG and the associated SecA ATPase. Using singlemolecule fluorescence we reveal that slow conformational changes associated with the ATPase SecA modulate fast opening and closure of the SecY lateral gate. Such a mismatch of timescales is not compatible with direct coupling between SecA and SecYEG. A dynamic allosteric model is proposed in which the SecA ATPase cycle ‘steers’ the energy landscape for SecY pore opening. We map the experimental traces onto reduced reaction coordinates derived from molecular dynamics trajectories, providing a model for the energy landscape and a structural interpretation of the associated dynamics. Dynamic allostery may be common among motor ATPases that drive conformational changes in molecular machines. ![Figure][1]</img> Graphical TOC Entry ### Competing Interest Statement The authors have declared no competing interest. [1]: pending:yes

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