Effects of lipids on the interaction of SecA with model membranes.
The effects of nonlamellar-prone lipids, diacylglycerol and phosphatidylethanolamine (PE), on the kinetic association of SecA with model membranes were examined by measuring changes in the intrinsic emission fluorescence with a stopped-flow apparatus. Upon interaction with standard liposomes composed of 50 mol% dioleolyphosphatidylcholine (DOPC) and 50 mol% of dioleoylphosphatidylglycerol (DOPG), the intrinsic fluorescence intensity of SecA was decreased after a lapse of time with a rate constant of 0.0049 s(-1). When the DOPC of the standard vesicles was gradually replaced with either dioeloyl PE (DOPE) or Escherichia coli (E. coli) PE, the rate constant increased appreciably as a function of PE concentration, in the order DOPE > E. coli PE. In addition, when the PE of E. coli PE/DOPG (50/50) vesicles was replaced with more than 5 mol% dioleoylglycerol (DOG), the rate constant further increased by 40%. The incorporation of nonlamellar-prone lipids in the vesicles also enhanced the binding of SecA to model membranes in the order DOPE > or = E. coli PE/DOG > E. coli PE > DOPC. These results provide the first kinetic evidence for the importance of nonlamellar-prone phospholipids for the association rate of SecA with membranes.
Ahn
T
T
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon, 305-701, Republic of Korea.
Kim
J S
JS
Lee
B C
BC
Yun
C H
CH
D000251:Adenosine Triphosphatases / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D004075:Diglycerides / Q000737:chemistry; D029968:Escherichia coli Proteins; D004983:Ethanolamines / Q000737:chemistry; D017022:Flow Injection Analysis; D020404:Glycerophospholipids; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000737:chemistry* / Q000494:pharmacology; D008081:Liposomes / Q000737:chemistry; D026901:Membrane Transport Proteins / Q000737:chemistry*; D008567:Membranes, Artificial; D008954:Models, Biological; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry; D011485:Protein Binding / Q000187:drug effects; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D013050:Spectrometry, Fluorescence
C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D001426:Bacterial Proteins; D004075:Diglycerides; D029968:Escherichia coli Proteins; D004983:Ethanolamines; D020404:Glycerophospholipids; D008051:Lipid Bilayers; D008055:Lipids; D008081:Liposomes; D026901:Membrane Transport Proteins; D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D000069816:SEC Translocation Channels; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol; C020888:1,2-dielaidoylphosphatidylethanolamine; C005448:phosphorylethanolamine; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins; C017251:1,2-oleoylphosphatidylcholine; C013965:diolein