title: Lipopolysaccharide heterogeneity in Escherichia coli J5 variants: analysis by flow cytometry.
abstract: A lipopolysaccharide O-side chain-producing phenotypic variant was isolated from a uridine 5'-diphosphogalactose 4-epimeraseless Escherichia coli J5 rough mutant strain by fluorescence-activated cell sorting with a monoclonal antibody (MAb) specific for the O-side chain of E. coli O111:B4 smooth parent lipopolysaccharide. The variant (J5-2) was recognized by both core- and O-side chain-specific MAbs, while the "original" rough mutant (J5-1) and smooth parent strains stained only with core- and O-side chain-specific MAb, respectively. J5-2 produced complete and incomplete (Rc chemotype) core and O polysaccharide in the presence of galactose. Three other E. coli J5 variants were either phenotypically similar to J5-1 (J5-UK) or distinct from J5-1 and J5-2 (J5-A, -B). The latter phenotype had a lower-molecular-weight core, compared with J5-1 and J5-2, and distinct MAb specificities. Various J5 phenotypes also differed in galactokinase levels, the ability to use galactose, and susceptibility to core-specific MAb binding on solid media. The J5-2 strain showed reciprocal changes in O-side chain and core expression during log-phase growth. E. coli J5 thus undergoes spontaneous alterations in lipopolysaccharide phenotype.
authors.affiliation: Department of Medicine, Uniformed Services University of the Health Sciences, F. Edward Hébert School of Medicine, Bethesda, Maryland 20814-4799.
authors.forename: M E
authors.initials: ME
authors.lastname: Evans
authors.forename: M
authors.initials: M
authors.lastname: Pollack
authors.forename: N L
authors.initials: NL
authors.lastname: Koles
authors.forename: N J
authors.initials: NJ
authors.lastname: Hardegen
authors.forename: D
authors.initials: D
authors.lastname: Panopoulos
mesh_terms: D000911:Antibodies, Monoclonal / Q000378:metabolism; D002469:Cell Separation; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D005434:Flow Cytometry; D015151:Immunoblotting; D008070:Lipopolysaccharides / Q000032:analysis / Q000096:biosynthesis*; D010641:Phenotype
chemical_list: D000911:Antibodies, Monoclonal; D008070:Lipopolysaccharides