title: SecYEG assembles into a tetramer to form the active protein translocation channel.
abstract: Translocase mediates preprotein translocation across the Escherichia coli inner membrane. It consists of the SecYEG integral membrane protein complex and the peripheral ATPase SecA. Here we show by functional assays, negative-stain electron microscopy and mass measurements with the scanning transmission microscope that SecA recruits SecYEG complexes to form the active translocation channel. The active assembly of SecYEG has a side length of 10.5 nm and exhibits an approximately 5 nm central cavity. The mass and structure of this SecYEG as well as the subunit stoichiometry of SecA and SecY in a soluble translocase-precursor complex reveal that translocase consists of the SecA homodimer and four SecYEG complexes.
authors.affiliation: Department of Microbiology, Groningen Biomolecular Sciences, Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
authors.forename: E H
authors.initials: EH
authors.lastname: Manting
authors.forename: C
authors.initials: C
authors.lastname: van Der Does
authors.forename: H
authors.initials: H
authors.lastname: Remigy
authors.forename: A
authors.initials: A
authors.lastname: Engel
authors.forename: A J
authors.initials: AJ
authors.lastname: Driessen
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D019281:Dimerization; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D000069816:SEC Translocation Channels
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C088616:SecG protein, E coli; C057841:SecY protein, E coli