RT Journal Article
SR Electronic
T1 Energy landscape steering in SecYEG mediates dynamic coupling in ATP driven protein translocation
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 793943
DO 10.1101/793943
A1 Joel Crossley
A1 Matthew A. Watson
A1 Tomas Fessl
A1 Daniel Watkins
A1 Robin A. Corey
A1 Tara Sabir
A1 Sheena E. Radford
A1 Ian Collinson
A1 Roman Tuma
YR 2019
UL http://biorxiv.org/content/early/2019/10/05/793943.abstract
AB 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 is driven by allosteric communication between the membrane pore SecYEG and the associated SecA ATPase. Using time-resolved single molecule fluorescence we reveal that slow conformational changes associated with SecA ATPase (∼ 6 s−1) modulate fast opening and closure of the SecY pore (∼ 175 s−1). Such mismatch of timescales is not compatible with direct coupling between SecA and SecYEG and the power stroke mechanism. A dynamic allosteric model in which SecA ATPase cycle controls energy landscape for SecY pore opening is proposed and consistent with the Brownian-ratchet mechanism. Analysis of structures and molecular dynamics trajectories identified key molecular interactions involved in the mechanism. This dynamic allostery may be common among motor ATPases that drive conformational changes in molecular machines.