The lateral gate of SecYEG opens during protein translocation.
The SecYEG translocon of Escherichia coli mediates the translocation of preproteins across the cytoplasmic membrane. Here, we have examined the role of the proposed lateral gate of the translocon in translocation. A dual cysteine cross-linking approach allowed the introduction of cross-linker arms of various lengths between adjoining aminoacyl positions of transmembrane segments 2b and 7 of the lateral gate. Oxidation and short spacer linkers that fix the gate in the closed state abolished preprotein translocation, whereas long spacer linkers support translocation. The cross-linking data further suggests that SecYEG lateral gate opening and activation of the SecA ATPase are coupled processes. It is concluded that lateral gate opening is a critical step during SecA-dependent protein translocation.
Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9751 NN Haren, The Netherlands.
David J F
DJ
du Plessis
Greetje
G
Berrelkamp
Nico
N
Nouwen
Arnold J M
AJ
Driessen
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D019605:Euryarchaeota / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010447:Peptide Hydrolases / Q000378:metabolism; D018272:Porins / Q000378:metabolism; D011487:Protein Conformation; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000235:genetics; D000069816:SEC Translocation Channels
C096310:AsmA protein, E coli; D001426:Bacterial Proteins; D004220:Disulfides; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D018272:Porins; D011498:Protein Precursors; D000069816:SEC Translocation Channels; C405564:ompT protein, bacteria; D010447:Peptide Hydrolases; D003545:Cysteine