Open AccessComparison of the phenotypes of the lpxA and lpxD mutants of Escherichia coli
Author(s) -
Vuorio Riitta,
Vaara Martti
Publication year - 1995
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1995.tb07942.x
Subject(s) - periplasmic space , mutant , bacterial outer membrane , escherichia coli , phenotype , strain (injury) , chemistry , biology , membrane permeability , biochemistry , microbiology and biotechnology , membrane , gene , anatomy
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 β‐lactamase was released from SM101 at 28°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 β‐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 ::Tn 10 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 phenotypic properties. A method for the estimation of lipid A synthesis rate was developed.