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: The process of guanosine 5'-diphosphate L-fucose (GDP-L-fucose) biosynthesis is conserved throughout evolution from prokaryotes to man. In animals, GDP-L-fucose is the substrate of fucosyltransferases that participate in the biosynthesis and remodeling of glycoconjugates, including ABH blood group and Lewis-system antigens. The 'de novo' pathway of GDP-L-fucose biosynthesis from GDP-D-mannose involves a GDP-D-mannose 4,6 dehydratase (GMD) and a GDP-4-keto-6-deoxy-D-mannose epimerase/reductase (GMER). Neither of the catalytic mechanisms nor the three-dimensional structures of the two enzymes has been elucidated yet. The severe leukocyte adhesion deficiency (LAD) type II genetic syndrome is known to result from deficiencies in this de novo pathway. RESULTS: The crystal structures of apo- and holo-GMER have been determined at 2.1 A and 2.2 A resolution, respectively. Each subunit of the homodimeric (2 x 34 kDa) enzyme is composed of two domains. The N-terminal domain, a six-stranded Rossmann fold, binds NADP+; the C-terminal domain (about 100 residues) displays an alpha/beta topology. NADP+ interacts with residues Arg12 and Arg36 at the adenylic ribose phosphate; moreover, a protein loop based on the Gly-X-X-Gly-X-X-Gly motif (where X is any amino acid) stabilizes binding of the coenzyme diphosphate bridge. The nicotinamide and the connected ribose ring are located close to residues Ser107, Tyr136 and Lys140, the putative GMER active-site center. CONCLUSIONS: The GMER fold is reminiscent of that observed for UDP-galactose epimerase (UGE) from Escherichia coli. Consideration of the enzyme fold and of its main structural features allows assignment of GMER to the reductase-epimerase-dehydrogenase (RED) enzyme homology superfamily, to which short-chain dehydrogenase/reductases (SDRs) also belong. The location of the NADP+ nicotinamide ring at an interdomain cleft is compatible with substrate binding in the C-terminal domain.
GDP-4-keto-6-deoxy-D-mannose epimerase/reductase from Escherichia coli, a key enzyme in the biosynthesis of GDP-L-fucose, displays the structural characteristics of the RED protein homology superfamily.,Rizzi M, Tonetti M, Vigevani P, Sturla L, Bisso A, Flora AD, Bordo D, Bolognesi M Structure. 1998 Nov 15;6(11):1453-65. PMID:9817848[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
- ↑ Rizzi M, Tonetti M, Vigevani P, Sturla L, Bisso A, Flora AD, Bordo D, Bolognesi M. GDP-4-keto-6-deoxy-D-mannose epimerase/reductase from Escherichia coli, a key enzyme in the biosynthesis of GDP-L-fucose, displays the structural characteristics of the RED protein homology superfamily. Structure. 1998 Nov 15;6(11):1453-65. PMID:9817848
