The periplasmic chaperone PpiD interacts with secretory proteins exiting from the SecYEG translocon.
The Sec translocon of Escherichia coli mediates the export of numerous secretory and membrane proteins. To dissect the passage of an exported protein across the Sec translocon into consecutive steps, we generated in vitro translocation intermediates of a polypeptide chain, which by its N-terminus is anchored in the membrane and by its C-terminus tethered to the ribosome. We find that in this situation, the motor protein SecA propagates translocation of a peptide loop across SecYEG prior to the removal of ribosomes. Upon SecA-driven exit from the translocon, this loop is brought into the immediate vicinity of the membrane-anchored, periplasmic chaperone PpiD. Consistent with a coupling between translocation across the SecYEG translocon and folding by periplasmic chaperones, a lack of PpiD retards the release of a translocating outer membrane protein into the periplasm.
Antonoaea
Raluca
R
Institut für Biochemie and Molekularbiologie and Zentrum für Biochemie and Molekulare Zellforschung, Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany.
Fürst
Michaela
M
Nishiyama
Ken-Ichi
K
Müller
Matthias
M
D002462:Cell Membrane / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport
D029968:Escherichia coli Proteins; D018832:Molecular Chaperones