PMID:11830594
| Citation |
Vorachek-Warren, MK, Carty, SM, Lin, S, Cotter, RJ and Raetz, CR (2002) An Escherichia coli mutant lacking the cold shock-induced palmitoleoyltransferase of lipid A biosynthesis: absence of unsaturated acyl chains and antibiotic hypersensitivity at 12 degrees C. J. Biol. Chem. 277:14186-93 |
|---|---|
| Abstract |
An acyltransferase induced by cold shock in Escherichia coli, designated LpxP, incorporates a palmitoleoyl moiety into nascent lipid A in place of the secondary laurate chain normally added by LpxL(HtrB) (Carty, S. M., Sreekumar, K. R., and Raetz, C. R. H. (1999) J. Biol. Chem. 274, 9677-9685). To determine whether the palmitoleoyl residue alters the properties of the outer membrane and imparts physiological benefits at low growth temperatures, we constructed a chromosomal insertion mutation in lpxP, the structural gene for the transferase. Membranes from the lpxP mutant MKV11 grown at 12 degrees C lacked the cold-induced palmitoleoyltransferase present in membranes of cold-shocked wild type cells but retained normal levels of the constitutive lauroyltransferase encoded by lpxL. When examined by mass spectrometry, about two-thirds of the lipid A molecules isolated from wild type E. coli grown at 12 degrees C contained palmitoleate in place of laurate, whereas the lipid A of cold-adapted MKV11 contained only laurate in amounts comparable with those seen in wild type cells grown at 30 degrees C or above. To probe the integrity of the outer membrane, MKV11 and an isogenic wild type strain were grown at 30 or 12 degrees C and then tested for their susceptibility to antibiotics. MKV11 exhibited a 10-fold increase in sensitivity to rifampicin and vancomycin at 12 degrees C compared with wild type cells but showed identical resistance when grown at 30 degrees C. We suggest that the palmitoleoyltransferase may confer a selective advantage upon E. coli cells growing at lower temperatures by making the outer membrane a more effective barrier to harmful chemicals. |
| Links |
PubMed Online version:10.1074/jbc.M200408200 |
| Keywords |
Acyltransferases/metabolism; Carbohydrate Sequence; Cell Membrane; Cold Temperature; DNA/metabolism; Electrophoresis, Polyacrylamide Gel; Escherichia coli/genetics; Escherichia coli Proteins; Lipid A/biosynthesis; Lipids; Mass Spectrometry; Molecular Sequence Data; Mutation; Plasmids/metabolism; Promoter Regions, Genetic; Rifampin/pharmacology; Temperature; Time Factors; Vancomycin/pharmacology |
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