STRUCTURAL-ANALYSIS OF O4-REACTIVE POLYSACCHARIDES FROM RECOMBINANT ESCHERICHIA-COLI - CHANGES IN THE O-SPECIFIC POLYSACCHARIDE INDUCED BY CLONING OF THE RFB GENES

In previous studies it had been shown that lipopolysaccharide from O4- specific recombinant Escherichia coli, had serological reactivities an d a chemical composition that differed from wild-type O4 LPS [Haraguch i, G. E., Zahringer, U., Jann, B., Jann, K., Hull, R. A. & Hull, S. 1. (1991) Microb. Pathog. 10, 351-3611. Here we present the structural e lucidation of the 0-specific moieties from lipopolysaccharides of some of the recombinant strains obtained in previous studies. Compositiona l analysis, methylation, chemical reactions and NMR spectroscopy showe d that, during genetic manipulations (recombination, cosmid cloning, p lasmid subcloning), a gradual structural change in the O-specific poly saccharides was observed in the recombinant strains. These changes com prised of an alteration in the position of glucose (side chain) substi tution, a change in the anomeric configuration of the main-chain N-ace tylglucosamine and an exchange of alpha-L-rhamnopyranose for beta-D-ga lactofuranose. The relevance of these results for lipopolysaccharide c loning and lipopolysaccharide biosynthesis are discussed.