title: Binding, activation and dissociation of the dimeric SecA ATPase at the dimeric SecYEG translocase.
abstract: The bacterial preprotein translocase is comprised of a membrane-embedded oligomeric SecYEG structure and a cytosolic dimeric SecA ATPase. The associations within SecYEG oligomers and SecA dimers, as well as between these two domains are dynamic and reversible. Here, it is shown that a covalently linked SecYEG dimer forms a functional translocase and a high affinity binding site for monomeric and dimeric SecA in solution. The interaction between these two domains stimulates the SecA ATPase, and nucleotides modulate the affinity and ratio of SecA monomers and dimers bound to the linked SecYEG complex. During the translocation reaction, the SecA monomer remains in stable association with a SecYEG protomer and the translocating preprotein. The nucleotides and translocation-dependent changes of SecA-SecYEG associations and the SecA dimeric state may reflect important facets of the preprotein translocation reaction.
authors.affiliation: Laboratoire Transports et Signalisations Cellulaires, CNRS-UMR 8619, Université de Paris XI, Bâtiment 430, Orsay 91405, France. Franck.Duong@genesis.u-psud.fr
authors.forename: Franck
authors.initials: F
authors.lastname: Duong
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins; D001665:Binding Sites; D019281:Dimerization; D004789:Enzyme Activation; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D021122:Protein Subunits; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C088616:SecG protein, E coli; C057841:SecY protein, E coli; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins