Mechanism of Conversion of the Salmonella O Antigen by Bacteriophage ε34

The structural determinants for antigen 34 in the E group salmonella are glucosyl substituents on the galactosyl units of the O antigen which has a mannosylrhamnosylgalactose repeating sequence. The temperate bacteriophage ε 34 brings about the production of antigen 34. It has been shown here that glucose is transferred from uridine diphosphate glucose to the O antigen via a glucosyl-lipid intermediate in a two-step reaction. Glucose is linked through carbon 1 to the lipid by a phosphodiester bridge, the glucosyl bond having the β-anomeric configuration. The lipid is a C 55 -polyisoprenoid alcohol, each isoprene unit having one double bond. It is the same lipid which is involved in the synthesis of the O antigen repeating sequence.