Structure and mechanism of Helicobacter pylori fucosyltransferase. A basis for lipopolysaccharide variation and inhibitor design.
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.
Sun
Han-Yu
HY
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.
Lin
Sheng-Wei
SW
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.
Ko
Tzu-Ping
TP
Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan.
Pan
Jia-Fu
JF
Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan.
Liu
Chia-Ling
CL
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.
Lin
Chun-Nan
CN
Institute of Biological Chemistry, Academia Sinica, No.128 Academia Road Section 2, Nan-Kang, Taipei 11529, Taiwan.
Wang
Andrew H-J
AH
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. Electronic address: ahjwang@gate.sinica.edu.tw.
Lin
Chun-Hung
CH
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. Electronic address: chunhung@gate.sinica.edu.tw.
D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000138:chemical synthesis*; D005647:Fucosyltransferases / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000502:physiology; D016480:Helicobacter pylori / Q000737:chemistry / Q000201:enzymology*; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000737:chemistry*; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D005647:Fucosyltransferases