TY - JOUR
T1 - An Escherichia coli mutant lacking the cold shock-induced palmitoleoyltransferase of lipid A biosynthesis. Absence of unsaturated acyl chains and antibiotic hypersensitivity at 12 °C
AU - Vorachek-Warren, Mara K.
AU - Carty, Sherry M.
AU - Lin, Shanhua
AU - Cotter, Robert J.
AU - Raetz, Christian R.H.
PY - 2002/4/19
Y1 - 2002/4/19
N2 - 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 °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 °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 °C or above. To probe the integrity of the outer membrane, MKV11 and an isogenic wild type strain were grown at 30 or 12 °C and then tested for their susceptibility to antibiotics. MKV11 exhibited a 10-fold increase in sensitivity to rifampicin and vancomycin at 12 °C compared with wild type cells but showed identical resistance when grown at 30 °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.
AB - 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 °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 °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 °C or above. To probe the integrity of the outer membrane, MKV11 and an isogenic wild type strain were grown at 30 or 12 °C and then tested for their susceptibility to antibiotics. MKV11 exhibited a 10-fold increase in sensitivity to rifampicin and vancomycin at 12 °C compared with wild type cells but showed identical resistance when grown at 30 °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.
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U2 - 10.1074/jbc.M200408200
DO - 10.1074/jbc.M200408200
M3 - Article
C2 - 11830594
AN - SCOPUS:0037134520
SN - 0021-9258
VL - 277
SP - 14186
EP - 14193
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 16
ER -