TY - JOUR
T1 - Relaxed acyl chain specificity of Bordetella UDP-N-acetylglucosamine acyltransferases
AU - Sweet, Charles R.
AU - Preston, Andrew
AU - Toland, Elinor
AU - Ramirez, Suzanne M.
AU - Cotter, Robert J.
AU - Maskell, Duncan J.
AU - Raetz, Christian R.H.
PY - 2002/5/24
Y1 - 2002/5/24
N2 - Lipid A (endotoxin) is a major structural component of Gram-negative outer membranes. It also serves as the hydrophobic anchor of lipopolysaccharide and is a potent activator of the innate immune response. Lipid A molecules from the genus Bordetella are reported to exhibit unusual structural asymmetry with respect to the acyl chains at the 3- and 3'-positions. These acyl chains are attached by UDP-N-acetylglucosamine acyl-transferase (LpxA). To determine the origin of the acyl variability, the single lpxA ortholog present in each of the genomes of Bordetella bronchiseptica (lpxABr), Bordetella parapertussis (lpxAPe) and Bordetella pertussis (lpxAPe) was cloned and expressed in Escherichia coli. In contrast to all LpxA proteins studied to date, LpxABr and LpxAPe display relaxed acyl chain length specificity in vitro, utilizing C10OH-ACP, C12OH-ACP, and C14OH-ACP at similar rates. Furthermore, hybrid lipid A molecules synthesized at 42 °C by an E. coli lpxA mutant complemented with lpxAPe contain C10OH, C12OH and C14OH at both the 3- and 3′-positions, as determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In contrast, LpxA from B. parapertussis did not display relaxed specificity but was selective for C10OH-ACP. This study provides an enzymatic explanation for some of the unusual acyl chain variations found in Bordetella lipid A.
AB - Lipid A (endotoxin) is a major structural component of Gram-negative outer membranes. It also serves as the hydrophobic anchor of lipopolysaccharide and is a potent activator of the innate immune response. Lipid A molecules from the genus Bordetella are reported to exhibit unusual structural asymmetry with respect to the acyl chains at the 3- and 3'-positions. These acyl chains are attached by UDP-N-acetylglucosamine acyl-transferase (LpxA). To determine the origin of the acyl variability, the single lpxA ortholog present in each of the genomes of Bordetella bronchiseptica (lpxABr), Bordetella parapertussis (lpxAPe) and Bordetella pertussis (lpxAPe) was cloned and expressed in Escherichia coli. In contrast to all LpxA proteins studied to date, LpxABr and LpxAPe display relaxed acyl chain length specificity in vitro, utilizing C10OH-ACP, C12OH-ACP, and C14OH-ACP at similar rates. Furthermore, hybrid lipid A molecules synthesized at 42 °C by an E. coli lpxA mutant complemented with lpxAPe contain C10OH, C12OH and C14OH at both the 3- and 3′-positions, as determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In contrast, LpxA from B. parapertussis did not display relaxed specificity but was selective for C10OH-ACP. This study provides an enzymatic explanation for some of the unusual acyl chain variations found in Bordetella lipid A.
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U2 - 10.1074/jbc.M201057200
DO - 10.1074/jbc.M201057200
M3 - Article
C2 - 11889134
AN - SCOPUS:0037166280
SN - 0021-9258
VL - 277
SP - 18281
EP - 18290
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 21
ER -