2pam
Structure of a H49N, H51N double mutant dTDP-4-keto-6-deoxy-D-glucose-3,4-ketoisomerase from Aneurinibacillus thermoaerophilus complexed with TDP
Structural highlights
FunctionFDTA_ANETH Mediates the isomerization of dTDP-6-deoxy-D-xylohex-4-ulose into dTDP-6-deoxy-D-xylohex-3-ulose in the biosynthesis of dTDP-3-acetamido-3,6-dideoxy-alpha-D-galactose, a glycan chain of the S-layer.[1] [2] 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 PubMedThe repeating unit of the glycan chain in the S-layer of the bacterium Aneurinibacillus thermoaerophilus L420-91(T) is composed of four alpha-d-rhamnose molecules and two 3-acetamido-3,6-dideoxy-alpha-d-galactose moieties (abbreviated as Fucp3NAc). Formation of the glycan layer requires nucleotide-activated sugars as the donor molecules. Whereas the enzymes involved in the synthesis of GDP-rhamnose have been well characterized, less is known regarding the structures and enzymatic mechanisms of the enzymes required for the production of dTDP-Fucp3NAc. One of the enzymes involved in the biosynthesis of dTDP-Fucp3NAc is a 3,4-ketoisomerase, hereafter referred to as FdtA. Here we describe the first three-dimensional structure of this sugar isomerase complexed with dTDP and solved to 1.5 A resolution. The FdtA dimer assumes an almost jellyfish-like appearance with the sole alpha-helices representing the tentacles. Formation of the FdtA dimer represents a classical example of domain swapping whereby beta-strands 2 and 3 from one subunit form part of a beta-sheet in the second subunit. The active site architecture of FdtA is characterized by a cluster of three histidine residues, two of which, His(49) and His(51), appear to be strictly conserved in the amino acid sequences deposited to date. Site-directed mutagenesis experiments, enzymatic assays, and x-ray crystallographic analyses suggest that His(49) functions as an active site base. The x-ray structure of dTDP-4-keto-6-deoxy-D-glucose-3,4-ketoisomerase.,Davis ML, Thoden JB, Holden HM J Biol Chem. 2007 Jun 29;282(26):19227-36. Epub 2007 Apr 25. PMID:17459872[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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