Glycosyltransferases of Pseudomonas aeruginosa that assemble the O antigens of A band and B band lipopolysaccharide

Pseudomonas aeruginosa produces two forms of lipopolysaccharide (LPS) desig nated A band and B band. The O-polysaccharide region of A band is a conserv ed D-rhamnan polymer arranged alpha 1-2, alpha 1-3, alpha 1-3, while B band is serotype-specific with differences in the O-antigenic region dividing P . aeruginosa into 20 stereotypes. The B band O-antigen unit of serotype O5 is [-4)-beta-D-Man(2NAc3N)A-(1-4)-beta-D-Man(2NAc3NAc)A-(1-3)-alpha-D-Fuc2N Ac]. The glycosidic structure of LPS molecules specified by the action of d edicated glycosyltransferases. The wbp clusters of A band and B band (serot ype O5) were each found to contain three genes coding for putative glycosyl transferases: wbpX, wbpY, wbpZ, and wbpH, wbpJ, wbpL, respectively. To exam ine the role of these potential transferases in LPS assembly, chromosomal m utations were generated within all 6 genes. LPS analysis reveals that wbpX, wbpY, and wbpZ mutants express an A(-)B(+) phenotype, while wbpH and wbpJ mutants are A(+)B(-). interestingly, mutations in wbpL, an Escherichia coil wecA homologue, abrogates both A band and B band LPS synthesis. Based on a mino acid homologies, O-polysaccharide structures and LPS phenotypes of tra nsferase mutants, we propose an assembly scheme for these two LPS molecules .