title: SecA of Escherichia coli traverses lipid bilayer of phospholipid vesicles.
abstract: SecA protein of Escherichia coli, when added externally to the vesicles composed of phosphatidylethanolamine, dioleoylphosphatidylglycerol and cardiolipin, was found to be fragmented by trypsin encapsulated within the vesicles. In the presence of ATP or its non-hydrolyzing analogue, ATP-gamma S, the number of fragments and extent of hydrolysis occurred much less than in the absence of these compounds. When ADP was added, however, the hydrolysis products were similar to those when no nucleotide was present. Quenching of SecA fluorescence by vesicle-entrapped iodide corroborated the digestion results. These experiments demonstrated that the SecA protein traverses the lipid bilayer and its membrane topology depends on the kind of nucleotide present.
authors.affiliation: Department of Life Science, Korea Advanced Institute of Science and Technology, Taejon.
authors.forename: T
authors.initials: T
authors.lastname: Ahn
authors.forename: H
authors.initials: H
authors.lastname: Kim
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002308:Cardiolipins; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D008051:Lipid Bilayers; D026901:Membrane Transport Proteins; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D011485:Protein Binding; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D013050:Spectrometry, Fluorescence; D014357:Trypsin; D014364:Tryptophan
chemical_list: D001426:Bacterial Proteins; D002308:Cardiolipins; D029968:Escherichia coli Proteins; D008051:Lipid Bilayers; D026901:Membrane Transport Proteins; D010446:Peptide Fragments; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D000069816:SEC Translocation Channels; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol; D014364:Tryptophan; D014357:Trypsin; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins