Involvement of membrane lipids in protein export in Escherichia coli.
Several models for the transport of proteins across membranes predict a role for lipids. If these models are correct, then alterations in lipid metabolism may affect protein export and vice versa. We are investigating this possibility by studying Escherichia coli K-12 mutants with defects in protein export or phospholipid metabolism. A temperature-sensitive secA mutant, which is defective in protein export at 42 degrees C, exhibited severe pleiotropic effects on membrane biogenesis. Incubation of this strain at 42 degrees C resulted in the appearance of intracytoplasmic membranes, in alterations in lipopolysaccharide structure and in decreased cardiolipin and C18:1 fatty acid content. On the other hand, a pgsA mutant which is defective in the synthesis of acidic phospholipids, exhibited a protein export defect when studied in vivo or in vitro. These results are in agreement with a postulated role of membrane lipids in protein export.
Tommassen
J
J
Department of Molecular Cell Biology, University of Utrecht, The Netherlands.
de Vrije
T
T
de Cock
H
H
Bosch
D
D
de Kruijff
B
B
D001426:Bacterial Proteins / Q000378:metabolism*; D001692:Biological Transport / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D008563:Membrane Lipids / Q000235:genetics / Q000502:physiology*; D009154:Mutation
D001426:Bacterial Proteins; D008563:Membrane Lipids