[GLF1_KLEPN] Involved in the biosynthesis of the galactose-containing O-side-chain polysaccharide backbone structure of D-galactan I which is a key component of lipopolysaccharide (LPS). Catalyzes the interconversion through a 2-keto intermediate of uridine diphosphogalactopyranose (UDP-GalP) into uridine diphosphogalactofuranose (UDP-GalF) which is the biosynthetic precursor of galactofuranosyl residues.[1]
Evolutionary Conservation
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Publication Abstract from PubMed
Uridine diphosphogalactofuranose (UDP-Galf) is the precursor of the d-galactofuranose sugar found in bacterial and parasitic cell walls, including those of many pathogens. UDP-Galf is made from UDP-galactopyranose by the enzyme UDP-galactopyranose mutase. The enzyme requires the reduced FADH- co-factor for activity. The structure of the Mycobacterium tuberculosis mutase with FAD has been determined to 2.25 A. The structures of Klebsiella pneumoniae mutase with FAD and with FADH- bound have been determined to 2.2 A and 2.35 A resolution, respectively. This is the first report of the FADH(-)-containing structure. Two flavin-dependent mechanisms for the enzyme have been proposed, one, which involves a covalent adduct being formed at the flavin and the other based on electron transfer. Using our structural data, we have examined the two mechanisms. The electron transfer mechanism is consistent with the structural data, not surprisingly, since it makes fewer demands on the precise positioning of atoms. A model based on a covalent adduct FAD requires repositioning of the enzyme active site and would appear to require the isoalloxazine ring of FADH- to buckle in a particular way. However, the FADH- structure reveals that the isoalloxazine ring buckles in the opposite sense, this apparently requires the covalent adduct to trigger profound conformational changes in the protein or to buckle the FADH- opposite to that seen in the apo structure.
Crystal structures of Mycobacteria tuberculosis and Klebsiella pneumoniae UDP-galactopyranose mutase in the oxidised state and Klebsiella pneumoniae UDP-galactopyranose mutase in the (active) reduced state.,Beis K, Srikannathasan V, Liu H, Fullerton SW, Bamford VA, Sanders DA, Whitfield C, McNeil MR, Naismith JH J Mol Biol. 2005 May 13;348(4):971-82. PMID:15843027[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑Koplin R, Brisson JR, Whitfield C. UDP-galactofuranose precursor required for formation of the lipopolysaccharide O antigen of Klebsiella pneumoniae serotype O1 is synthesized by the product of the rfbDKPO1 gene. J Biol Chem. 1997 Feb 14;272(7):4121-8. PMID:9020123
↑Beis K, Srikannathasan V, Liu H, Fullerton SW, Bamford VA, Sanders DA, Whitfield C, McNeil MR, Naismith JH. Crystal structures of Mycobacteria tuberculosis and Klebsiella pneumoniae UDP-galactopyranose mutase in the oxidised state and Klebsiella pneumoniae UDP-galactopyranose mutase in the (active) reduced state. J Mol Biol. 2005 May 13;348(4):971-82. PMID:15843027 doi:10.1016/j.jmb.2005.02.057
