title: Competitive binding of the SecA ATPase and ribosomes to the SecYEG translocon.
abstract: During co-translational membrane insertion of membrane proteins with large periplasmic domains, the bacterial SecYEG complex needs to interact both with the ribosome and the SecA ATPase. Although the binding sites for SecA and the ribosome overlap, it has been suggested that these ligands can interact simultaneously with SecYEG. We used surface plasmon resonance and fluorescence correlation spectroscopy to examine the interaction of SecA and ribosomes with the SecYEG complex present in membrane vesicles and the purified SecYEG complex present in a detergent-solubilized state or reconstituted into nanodiscs. Ribosome binding to the SecYEG complex is strongly stimulated when the ribosomes are charged with nascent chains of the monotopic membrane protein FtsQ. This binding is competed by an excess of SecA, indicating that binding of SecA and ribosomes to SecYEG is mutually exclusive.
authors.affiliation: Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
authors.forename: Zht Cheng
authors.initials: ZC
authors.lastname: Wu
authors.forename: Jeanine
authors.initials: J
authors.lastname: de Keyzer
authors.forename: Alexej
authors.initials: A
authors.lastname: Kedrov
authors.forename: Arnold J M
authors.initials: AJ
authors.lastname: Driessen
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D019897:Periplasm / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*; D000069816:SEC Translocation Channels; D000081416:SecA Proteins
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D046912:Multiprotein Complexes; 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