Biosynthesis of the O9 antigen of Escherichia coli

Publisher Website
Google Scholar
Abstract
Synthetic monosaccharide derivatives (α‐glucosyl, β‐glucosyl, α‐mannosyl) and disaccharide derivative (α‐manosyl‐1,2‐α‐glucosyl, α‐mannosyl‐1,3‐α‐glucosyl, α‐mannosyl‐1,4‐α‐glucosyl, α‐mannosyl‐1,6‐α‐glucosyl) of diphosphomoraprenol were used as putative mannose acceptors in the biosynthesis of Escherichia coli O9 antigen. Membranes of E. coli O9 derived from the rfe mutant F 1357 were reconstituted with these compounds and then incubated with different concentrations of GDP‐[14C]mannose. Of the monosaccharide derivatives tested, only α‐glucodiphosphomoraprenol was a mannose acceptor and the only disaccharide derivative which accepted mannose was α‐mannosyl‐1,3‐α‐glucosyldiphosphomoraprenol. The α‐glucosyl derivative accepted only one mannose unit at 4 μM GDP‐[14C]mannose, and above 50 μM GDP‐[14C]mannose about 25% of the product had a minimum size of about 30 mannose units. The α‐mannosyl‐1,3‐α‐glucosyl derivative was only a mannose acceptor at a GDP‐[14C]mannose concentration of 50 μM and higher, and the product had a minimum size of about 30 mannose units. The results are discussed with respect to requirement of mannose acceptors.