A derivative of lipid A is involved in signal recognition particle/SecYEG-dependent and -independent membrane integrations.
A cell-free system was developed that allows the correct integration of single and multispanning membrane proteins of Escherichia coli into proteoliposomes. We found that physiological levels of diacylglycerol were required to prevent spontaneous integration into liposomes even of the polytopic mannitol permease. Using diacylglycerol-containing proteoliposomes, we identified a novel integration-stimulating factor. Integration of mannitol permease was dependent on both the SecYEG translocon and this factor and was mediated by signal recognition particle and signal recognition particle receptor. Integration of M13 procoat, which is independent of both signal recognition particle/signal recognition particle receptor and SecYEG, was also promoted by this factor. Furthermore, the factor stimulated the post-translational translocation of presecretory proteins, suggesting that it also mediates integration of a signal sequence. This factor was found to be a lipid A-derived membrane component possessing a peptide moiety.
Nishiyama
Ken-ichi
K
Institute of Biochemistry and Molecular Biology, Centre of Biochemistry and Molecular Cell Research, University of Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany. unishiy@mail.ecc.u-tokyo.ac.jp
Ikegami
Ayao
A
Moser
Michael
M
Schiltz
Emile
E
Tokuda
Hajime
H
Müller
Matthias
M
D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry; D002474:Cell-Free System; D004075:Diglycerides / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D008050:Lipid A / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D008565:Membrane Proteins / Q000378:metabolism*; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry; D021381:Protein Transport; D011510:Proteolipids / Q000737:chemistry; D000069816:SEC Translocation Channels; D018271:Signal Recognition Particle / Q000737:chemistry*
D001425:Bacterial Outer Membrane Proteins; D004075:Diglycerides; D029968:Escherichia coli Proteins; D008050:Lipid A; D008055:Lipids; D008081:Liposomes; D008565:Membrane Proteins; D010455:Peptides; D011510:Proteolipids; D000069816:SEC Translocation Channels; C065493:SecE protein, E coli; C088616:SecG protein, E coli; C057841:SecY protein, E coli; D018271:Signal Recognition Particle; C020485:proteoliposomes; C078167:OMPA outer membrane proteins