A dual role for phosphatidylglycerol in protein translocation across the Escherichia coli inner membrane.
The involvement of phosphatidylglycerol in the SecA-independent translocation of M13 procoat in Escherichia coli was demonstrated. Processing of procoat to mature coat protein was retarded when the level of phosphatidylglycerol was reduced. In vitro translocation experiments using inner membrane vesicles isolated from a strain with inducible synthesis of phosphatidylglycerol, showed that translocation of procoat and of a SecA-dependent procoat analog was proportional to the content of phosphatidylglycerol. Moreover, introduction of phosphatidylglycerol by means of a lipid transfer method into phosphatidylglycerol-depleted inner membrane vesicles, efficiently restored procoat translocation. The phosphatidylglycerol dependence in both the SecA-dependent and -independent translocation pathway indicates that phosphatidylglycerol plays a dual role in translocation. We suggest that besides membrane binding of SecA this lipid has a direct interaction with the M13 procoat in translocation across the inner membrane.
Kusters
R
R
Department of Biochemistry, University of Utrecht, The Netherlands.
Breukink
E
E
Gallusser
A
A
Kuhn
A
A
de Kruijff
B
B
D000251:Adenosine Triphosphatases / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D017104:Bacteriophage M13 / Q000378:metabolism; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D010715:Phosphatidylglycerols / Q000502:physiology*; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D014764:Viral Proteins / Q000378:metabolism
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D010715:Phosphatidylglycerols; D011498:Protein Precursors; D000069816:SEC Translocation Channels; D014764:Viral Proteins; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins