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Title: Quaternary dynamics of the SecA motor drive translocase catalysis
Authors: Gouridis, Giorgos ×
Karamanou, Lily
Sardis, Marios Frantzeskos
Schärer, Martin Alexander
Capitani, Guido
Economou, Anastassios #
Issue Date: Dec-2013
Publisher: Cell Press
Series Title: Molecular Cell vol:52 issue:5 pages:655-66
Article number: 10.1016/j.molcel.2013.10.036
Abstract: Most secretory preproteins exit bacterial cells through the protein translocase, comprising the SecYEG channel and the dimeric peripheral ATPase motor SecA. Energetic coupling to work remains elusive. We now demonstrate that translocation is driven by unusually dynamic quaternary changes in SecA. The dimer occupies several successive states with distinct protomer arrangements. SecA docks on SecYEG as a dimer and becomes functionally asymmetric. Docking occurs via only one protomer. The second protomer allosterically regulates downstream steps. Binding of one preprotein signal peptide to the SecYEG-docked SecA protomer elongates the SecA dimer and triggers the translocase holoenzyme to obtain a lower activation energy conformation. ATP hydrolysis monomerizes the triggered SecA dimer, causing mature chain trapping and processive translocation. This is a unique example of one protein exploiting quaternary dynamics to become a substrate receptor, a "loading clamp," and a "processive motor." This mechanism has widespread implications on protein translocases, chaperones, and motors.
URI: 
ISSN: 1097-2765
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Molecular Bacteriology (Rega Institute)
× corresponding author
# (joint) last author

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