Functional genomics of Helicobacter pylori: identification of a beta-1,4 galactosyltransferase and generation of mutants with altered lipopolysaccharide

A previously annotated open reading frame (ORF) (HP0826) from Helicobacter pylori was cloned and expressed in Escherichia coli cells and determined to be a beta-1,4-galactosyltransferase that used GlcNAc as an acceptor. Mutat ional analysis in H. pylori strains demonstrated that this enzyme plays a k ey role in the biosynthesis of the type 2 N-acetyl-lactosamine (LacNAc) pol ysaccharide O-chain backbone, by catalysing the addition of Gal to GlcNAc. To examine the potential role of this O-chain structure in bacterial coloni zation of the host stomach, the mutation was introduced into H. pylori stra in SS1 which is known to be capable of colonizing the gastric mucosa of mic e. Compared with the parental strain, mutated SS1 was less efficient at col onizing the murine stomach.