title: Comparison of the phenotypes of the lpxA and lpxD mutants of Escherichia coli.
abstract: We compared the phenotype of two thermosensitive Escherichia coli mutants defective in lipid A biosynthesis, i.e. SM101 (lpxA) and CDH23-213 (lpxD). More than 40% of the periplasmic 27-kDa marker enzyme beta-lactamase was released from SM101 at 28 degrees C. At this temperature, the mutant still grew with a generation time (67 min), not much longer than that of the parent control strain (57 min). CDH23-213 released beta-lactamase only at higher temperatures. SM101 and CDH23-213 were both unable to grow in hypo-osmotic conditions. Derivatives of SM101 and CDH23-213 with mdoA::Tn10 had identical phenotypes (including thermosensitivity and defective outer membrane permeability barrier to hydrophobic probes) to those of SM101 and CDH23-213, indicating that the potential loss of membrane-derived oligosaccharides (MDO) did not explain these phenotype properties. A method for the estimation of lipid A synthesis rate was developed.
authors.affiliation: Department of Bacteriology and Immunology, University of Helsinki, Finland.
authors.forename: R
authors.initials: R
authors.lastname: Vuorio
authors.forename: M
authors.initials: M
authors.lastname: Vaara
mesh_terms: D000217:Acyltransferases / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D008050:Lipid A / Q000096:biosynthesis / Q000235:genetics*; D008070:Lipopolysaccharides / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D010712:Phosphatidic Acids / Q000378:metabolism; D013696:Temperature; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D008050:Lipid A; D008070:Lipopolysaccharides; D010712:Phosphatidic Acids; D000217:Acyltransferases; C050304:acyl-(acyl-carrier-protein)-UDP-N-acetylglucosamine acyltransferase; D001618:beta-Lactamases