Publications

• Formation of a new O-polysaccharide in Escherichia coli O86 via disruption of a glycosyltransferase gene involved in O-unit assembly.

  Yi W., Zhu L., Guo H., Li M., Li J., Wang P.G.

  The majority of hetero-polysaccharide biosynthesis in Gram-negative bacteria utilizes the wzy-dependent pathway, in which repeating O-units are first synthesized in the cytosol and then subsequently translocated to the periplasmic face of the inner membrane where polymerization is initiated by the ... >> More

  The majority of hetero-polysaccharide biosynthesis in Gram-negative bacteria utilizes the wzy-dependent pathway, in which repeating O-units are first synthesized in the cytosol and then subsequently translocated to the periplasmic face of the inner membrane where polymerization is initiated by the Wzy polymerase. Wzy proteins share little primary sequence homology and are specific for their cognate O-unit structures. Our previous studies on O-polysaccharide biosynthesis in Escherichia coli O86 identified the wbnI gene, which encodes a galactosyltransferase responsible for the introduction of alpha-(1-->3)-Galp residues as side chains of the polysaccharide. In this work, we functionally inactivated the wbnI gene and showed that the mutant strain produced a different polysaccharide without the side chain Galp residue. The yield of the polysaccharide was substantially lower than the one produced by the wild-type strain. This study indicated that the complete O-unit structure is the preferred substrate for the polymerization, thus further confirming the specificity of Wzy. On the other hand, these studies also suggest that the Wzy polymerase might have moderate tolerance of side-chain truncated O-unit substrates. << Less

  Carbohydr Res 341:2254-2260(2006) [PubMed] [EuropePMC]

• In vitro bacterial polysaccharide biosynthesis: defining the functions of Wzy and Wzz.

  Woodward R., Yi W., Li L., Zhao G., Eguchi H., Sridhar P.R., Guo H., Song J.K., Motari E., Cai L., Kelleher P., Liu X., Han W., Zhang W., Ding Y., Li M., Wang P.G.

  Polysaccharides constitute a major component of bacterial cell surfaces and play critical roles in bacteria-host interactions. The biosynthesis of such molecules, however, has mainly been characterized through in vivo genetic studies, thus precluding discernment of the details of this pathway. Acc ... >> More

  Polysaccharides constitute a major component of bacterial cell surfaces and play critical roles in bacteria-host interactions. The biosynthesis of such molecules, however, has mainly been characterized through in vivo genetic studies, thus precluding discernment of the details of this pathway. Accordingly, we present a chemical approach that enabled reconstitution of the E. coli O-polysaccharide biosynthetic pathway in vitro. Starting with chemically prepared undecaprenyl-diphospho-N-acetyl-D-galactosamine, the E. coli O86 oligosaccharide repeating unit was assembled by means of sequential enzymatic glycosylation. Successful expression of the putative polymerase Wzy using a chaperone coexpression system then allowed demonstration of polymerization in vitro using this substrate. Analysis of more substrates revealed a defined mode of recognition for Wzy toward the lipid moiety. Specific polysaccharide chain length modality was furthermore demonstrated to result from the action of Wzz. Collectively, polysaccharide biosynthesis was chemically reconstituted in vitro, providing a well defined system for further underpinning molecular details of this biosynthetic pathway. << Less

  Nat. Chem. Biol. 6:418-423(2010) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.

• Escherichia coli O86 O-antigen biosynthetic gene cluster and stepwise enzymatic synthesis of human blood group B antigen tetrasaccharide.

  Yi W., Shao J., Zhu L., Li M., Singh M., Lu Y., Lin S., Li H., Ryu K., Shen J., Guo H., Yao Q., Bush C.A., Wang P.G.

  Previous study showed that some Gram-negative bacteria possess human blood group activity. Among them, Escherichia coli O86 has high blood group B activity and weak blood group A activity. This is due to the cell surface O-antigen structure, which resembles that of human blood group B antigen. In ... >> More

  Previous study showed that some Gram-negative bacteria possess human blood group activity. Among them, Escherichia coli O86 has high blood group B activity and weak blood group A activity. This is due to the cell surface O-antigen structure, which resembles that of human blood group B antigen. In this study, we sequenced the entire E. coli O86 antigen gene cluster and identified all the genes responsible for O-antigen biosynthesis by sequence comparative analysis. The blood group B-like antigen in E. coli O86 O-polysaccharide was synthesized by sequentially employing three glycosyltransferases identified in the gene cluster. More importantly, we identified a new bacterial glycosyltransferase (WbnI) equivalent to human blood group transferase B (GTB). The enzyme substrate specificity and stepwise enzymatic synthesis of blood group B-like antigen revealed that the biosynthetic pathway of B antigen is essentially the same in E. coli O86 as in humans. This new finding provides a model to study the specificity and structure relationship of blood group transferases and supports the hypothesis of anti-blood group antibody production by bacterial stimulation. << Less

  J. Am. Chem. Soc. 127:2040-2041(2005) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.