Cloning of genes for bacterial glycosyltransferases. II. Selection of a hybrid plasmid carrying the rfah gene.

A hybrid ColE1 plasmid containing DNA from Escherichia coli K12 were identified which was capable of correcting the defect in UDP-galactose:lipopolysaccharide alpha1,3-galactosyltransferase in an rfaH mutant of Salmonella typhimurium. Expression of the gene for this enzyme was also demonstrated in several strains of E. coli by direct assay. The E. coli and S. typhimurium enzymes are similar in catalytic properties and immunologic specificity. The finding of the galactosyltransferase activity in E. coli extracts is surprising since the alpha1,3-galactosylglucose disaccharide which is the product of the enzyme-catalyzed reaction does not appear to be present in the E. coli lipopolysaccharide.