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Fan YY, Yu SY, Ito H, Kameyama A, Sato T, Lin CH, Yu LC, Narimatsu H, Khoo KH. Identification of Further Elongation and Branching of Dimeric Type 1 Chain on Lactosylceramides from Colonic Adenocarcinoma by Tandem Mass Spectrometry Sequencing Analyses. J Biol Chem 2008; 283:16455-68. [DOI: 10.1074/jbc.m707274200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Moran AP. Relevance of fucosylation and Lewis antigen expression in the bacterial gastroduodenal pathogen Helicobacter pylori. Carbohydr Res 2007; 343:1952-65. [PMID: 18279843 DOI: 10.1016/j.carres.2007.12.012] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Revised: 11/23/2007] [Accepted: 12/17/2007] [Indexed: 12/12/2022]
Abstract
Helicobacter pylori is a prevalent bacterial, gastroduodenal pathogen of humans that can express Lewis (Le) and related antigens in the O-chains of its surface lipopolysaccharide. The O-chains of H. pylori are commonly composed of internal Le(x) units with terminal Le(x) or Le(y) units or, in some strains, with additional units of Le(a), Le(b), Le(c), sialyl-Le(x) and H-1 antigens, as well as blood groups A and B, thereby producing a mosaicism of antigenic units expressed. The genetic determination of the Le antigen biosynthetic pathways in H. pylori has been studied, and despite striking functional similarity, low sequence homology occurs between the bacterial and mammalian alpha(1,3/4)- and alpha(1,2)-fucosyltransferases. Factors affecting Le antigen expression in H. pylori, that can influence the biological impact of this molecular mimicry, include regulation of fucosyltransferase genes through slipped-strand mispairing, the activity and expression levels of the functional enzymes, the preferences of the expressed enzyme for distinctive acceptor molecules and the availability of activated sugar intermediates. Le mimicry was initially implicated in immune evasion and gastric adaptation by the bacterium, but more recent studies show a role in gastric colonization and bacterial adhesion with galectin-3 identified as the gastric receptor for polymeric Le(x) on the bacterium. From the host defence aspect, innate immune recognition of H. pylori by surfactant protein D is influenced by the extent of LPS fucosylation. Furthermore, Le antigen expression affects both the inflammatory response and T-cell polarization that develops after infection. Although controversial, evidence suggests that long-term H. pylori infection can induce autoreactive anti-Le antibodies cross-reacting with the gastric mucosa, in part leading to the development of gastric atrophy. Thus, Le antigen expression and fucosylation in H. pylori have multiple biological effects on pathogenesis and disease outcome.
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Affiliation(s)
- Anthony P Moran
- Department of Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland.
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Sun HY, Lin SW, Ko TP, Pan JF, Liu CL, Lin CN, Wang AHJ, Lin CH. Structure and mechanism of Helicobacter pylori fucosyltransferase. A basis for lipopolysaccharide variation and inhibitor design. J Biol Chem 2007; 282:9973-9982. [PMID: 17251184 DOI: 10.1074/jbc.m610285200] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Helicobacter pylori alpha1,3-fucosyltransferase (FucT) is involved in catalysis to produce the Lewis x trisaccharide, the major component of the bacteria's lipopolysaccharides, which has been suggested to mimic the surface sugars in gastric epithelium to escape host immune surveillance. We report here three x-ray crystal structures of FucT, including the FucT.GDP-fucose and FucT.GDP complexes. The protein structure is typical of the glycosyltransferase-B family despite little sequence homology. We identified a number of catalytically important residues, including Glu-95, which serves as the general base, and Glu-249, which stabilizes the developing oxonium ion during catalysis. The residues Arg-195, Tyr-246, Glu-249, and Lys-250 serve to interact with the donor substrate, GDP-fucose. Variations in the protein and ligand conformations, as well as a possible FucT dimer, were also observed. We propose a catalytic mechanism and a model of polysaccharide binding not only to explain the observed variations in H. pylori lipopolysaccharides, but also to facilitate the development of potent inhibitors.
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Affiliation(s)
- Han-Yu Sun
- Institute of Biochemical Sciences, National Taiwan University, Taipei 10642; Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan
| | - Sheng-Wei Lin
- Institute of Biochemical Sciences, National Taiwan University, Taipei 10642; Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan
| | - Tzu-Ping Ko
- Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan
| | - Jia-Fu Pan
- Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan
| | - Chia-Ling Liu
- Institute of Biochemical Sciences, National Taiwan University, Taipei 10642; Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan
| | - Chun-Nan Lin
- Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan
| | - Andrew H-J Wang
- Institute of Biochemical Sciences, National Taiwan University, Taipei 10642; Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan; Genomics Research Center, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan; National Core Facility of High-Throughput Protein Crystallography, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan.
| | - Chun-Hung Lin
- Institute of Biochemical Sciences, National Taiwan University, Taipei 10642; Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan; Genomics Research Center, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan.
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Abstract
Fucosylated carbohydrate structures are involved in a variety of biological and pathological processes in eukaryotic organisms including tissue development, angiogenesis, fertilization, cell adhesion, inflammation, and tumor metastasis. In contrast, fucosylation appears less common in prokaryotic organisms and has been suggested to be involved in molecular mimicry, adhesion, colonization, and modulating the host immune response. Fucosyltransferases (FucTs), present in both eukaryotic and prokaryotic organisms, are the enzymes responsible for the catalysis of fucose transfer from donor guanosine-diphosphate fucose to various acceptor molecules including oligosaccharides, glycoproteins, and glycolipids. To date, several subfamilies of mammalian FucTs have been well characterized; these enzymes are therefore delineated and used as models. Non-mammalian FucTs that possess different domain construction or display distinctive acceptor substrate specificity are highlighted. It is noteworthy that the glycoconjugates from plants and schistosomes contain some unusual fucose linkages, suggesting the presence of novel FucT subfamilies as yet to be characterized. Despite the very low sequence homology, striking functional similarity is exhibited between mammalian and Helicobacter pylori alpha1,3/4 FucTs, implying that these enzymes likely share a conserved mechanistic and structural basis for fucose transfer; such conserved functional features might also exist when comparing other FucT subfamilies from different origins. Fucosyltranferases are promising tools used in synthesis of fucosylated oligosaccharides and glycoconjugates, which show great potential in the treatment of infectious and inflammatory diseases and tumor metastasis.
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Affiliation(s)
- Bing Ma
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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