An Escherichia coli mutant defective in lipid export.
Escherichia coli phospholipids and lipopolysaccharide, made on the inner surface of the inner membrane, are rapidly transported to the outer membrane by mechanisms that are not well characterized. We now report a temperature-sensitive mutant (WD2) with an A270T substitution in a trans-membrane region of the ABC transporter MsbA. As shown by (32)P(i) and (14)C-acetate labeling, export of all major lipids to the outer membrane is inhibited by approximately 90% in WD2 after 30 min at 44 degrees C. Transport of newly synthesized proteins is not impaired. Electron microscopy shows reduplicated inner membranes in WD2 at 44 degrees C, consistent with a key role for MsbA in lipid trafficking.
Departments of Biochemistry and Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
W T
WT
Doerrler
M C
MC
Reedy
C R
CR
Raetz
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins / Q000378:metabolism; D001692:Biological Transport; D002855:Chromatography, Thin Layer; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D050356:Lipid Metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D017354:Point Mutation
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D008565:Membrane Proteins; C079726:MsbA protein, Bacteria