Membrane binding of the bacterial signal recognition particle receptor involves two distinct binding sites.
Cotranslational protein targeting in bacteria is mediated by the signal recognition particle (SRP) and FtsY, the bacterial SRP receptor (SR). FtsY is homologous to the SRalpha subunit of eukaryotes, which is tethered to the membrane via its interaction with the membrane-integral SRbeta subunit. Despite the lack of a membrane-anchoring subunit, 30% of FtsY in Escherichia coli are found stably associated with the cytoplasmic membrane. However, the mechanisms that are involved in this membrane association are only poorly understood. Our data indicate that membrane association of FtsY involves two distinct binding sites and that binding to both sites is stabilized by blocking its GTPase activity. Binding to the first site requires only the NG-domain of FtsY and confers protease protection to FtsY. Importantly, the SecY translocon provides the second binding site, to which FtsY binds to form a carbonate-resistant 400-kD FtsY-SecY translocon complex. This interaction is stabilized by the N-terminal A-domain of FtsY, which probably serves as a transient lipid anchor.
Angelini
Sandra
S
Institute for Biochemistry and Molecular Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany.
Boy
Diana
D
Schiltz
Emile
E
Koch
Hans-Georg
HG
D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002254:Carbonates; D019286:Endopeptidase K; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D007425:Intracellular Membranes / Q000378:metabolism*; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018000:Receptors, Peptide / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D000069816:SEC Translocation Channels
D001426:Bacterial Proteins; D002254:Carbonates; D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; C087406:FtsY protein, Bacteria; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; D011994:Recombinant Proteins; D000069816:SEC Translocation Channels; C057841:SecY protein, E coli; C036318:signal peptide receptor; D006165:Guanylyl Imidodiphosphate; C005686:sodium carbonate; D019286:Endopeptidase K