Structural highlights
Function
[FCL_ECOLI] Catalyzes the two-step NADP-dependent conversion of GDP-4-dehydro-6-deoxy-D-mannose to GDP-fucose, involving an epimerase and a reductase reaction.[1] [2] [3]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Background:. In all species examined, GDP-fucose is synthesized from GDP-mannose in a three-step reaction catalyzed by two enzymes, GDP-mannose 4,6 dehydratase and a dual function 3, 5-epimerase-4-reductase named GDP-fucose synthetase. In this latter aspect fucose biosynthesis differs from that of other deoxy and dideoxy sugars, in which the epimerase and reductase activities are present as separate enzymes. Defects in GDP-fucose biosynthesis have been shown to affect nodulation in bacteria, stem development in plants, and are associated with the immune defect leukocyte adhesion deficiency type II in humans. Results:. We have determined the structure of GDP-fucose synthetase from Escherichia coli at 2.2 A resolution. The structure of GDP-fucose synthetase is closely related to that of UDP-galactose 4-epimerase and more distantly to other members of the short-chain dehydrogenase/reductase family. We have also determined the structures of the binary complexes of GDP-fucose synthetase with its substrate NADPH and its product NADP+. The nicotinamide cofactors bind in the syn and anti conformations, respectively. Conclusions:. GDP-fucose synthetase binds its substrate, NADPH, in the proper orientation (syn) for transferring the 4-pro-S hydride of the nicotinamide. We have observed a single binding site in GDP-fucose synthetase for the second substrate, GDP-4-keto,6-deoxy-mannose. This implies that both the epimerization and reduction reactions occur at the same site in the enzyme. As is the case for all members of the short-chain family of dehydrogenase/reductases, GDP-fucose synthetase retains the Ser-Tyr-Lys catalytic triad. We propose that this catalytic triad functions in a mechanistically equivalent manner in both the epimerization and reduction reactions. Additionally, the X-ray structure has allowed us to identify other residues that are potentially required for substrate binding and catalysis.
GDP-fucose synthetase from Escherichia coli: structure of a unique member of the short-chain dehydrogenase/reductase family that catalyzes two distinct reactions at the same active site.,Somers WS, Stahl ML, Sullivan FX Structure. 1998 Dec 15;6(12):1601-12. PMID:9862812[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Andrianopoulos K, Wang L, Reeves PR. Identification of the fucose synthetase gene in the colanic acid gene cluster of Escherichia coli K-12. J Bacteriol. 1998 Feb;180(4):998-1001. PMID:9473059
- ↑ Menon S, Stahl M, Kumar R, Xu GY, Sullivan F. Stereochemical course and steady state mechanism of the reaction catalyzed by the GDP-fucose synthetase from Escherichia coli. J Biol Chem. 1999 Sep 17;274(38):26743-50. PMID:10480878
- ↑ Rosano C, Bisso A, Izzo G, Tonetti M, Sturla L, De Flora A, Bolognesi M. Probing the catalytic mechanism of GDP-4-keto-6-deoxy-d-mannose Epimerase/Reductase by kinetic and crystallographic characterization of site-specific mutants. J Mol Biol. 2000 Oct 13;303(1):77-91. PMID:11021971 doi:10.1006/jmbi.2000.4106
- ↑ Somers WS, Stahl ML, Sullivan FX. GDP-fucose synthetase from Escherichia coli: structure of a unique member of the short-chain dehydrogenase/reductase family that catalyzes two distinct reactions at the same active site. Structure. 1998 Dec 15;6(12):1601-12. PMID:9862812
