3bn1
From Proteopedia
Crystal structure of GDP-perosamine synthase
Structural highlights
FunctionGDPPS_CAUVC Catalyzes the synthesis of GDP-perosamine from GDP-4-keto-6-deoxy-D-mannose and L-glutamate. Can use only L-glutamate as amino donor. In vitro, can also use GDP-4-keto-3,6-dideoxymannose to produce GDP-3-deoxyperosamine. Involved in the formation of S-LPS, which is required for attachment of the protein S-layer to the outer membrane surface.[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 PubMedPerosamine or 4-amino-4,6-dideoxy- d-mannose is an unusual sugar found in the O-antigens of some Gram-negative bacteria such as Vibrio cholerae O1 (the causative agent of cholera) or Escherichia coli O157:H7 (the leading cause of food-borne illnesses). It and similar deoxysugars are added to the O-antigens of bacteria via the action of glycosyltransferases that employ nucleotide-linked sugars as their substrates. The focus of this report is GDP-perosamine synthase, a PLP-dependent enzyme that catalyzes the last step in the formation of GDP-perosamine, namely, the amination of the sugar C-4'. Here we describe the three-dimensional structure of the enzyme from Caulobacter crescentus determined to a nominal resolution of 1.8 A and refined to an R-factor of 17.9%. The overall fold of the enzyme places it into the well-characterized aspartate aminotransferase superfamily. Each subunit of the dimeric enzyme contains a seven-stranded mixed beta-sheet, a two-stranded antiparallel beta-sheet, and 12 alpha-helices. Amino acid residues from both subunits form the active sites of the GDP-perosamine synthase dimer. Recently, the structure of another PLP-dependent enzyme, GDP-4-keto-6-deoxy- d-mannose-3-dehydratase (or ColD), was determined in our laboratory, and this enzyme employs the same substrate as GDP-perosamine synthase. Unlike GDP-perosamine synthase, however, ColD functions as a dehydratase that removes the sugar C-3' hydroxyl group. By purifying the ColD product and reacting it with purified GDP-perosamine synthase, we have produced a novel GDP-linked sugar, GDP-4-amino-3,4,6-trideoxy- d-mannose. Details describing the X-ray structural investigation of GDP-perosamine synthase and the enzymatic synthesis of GDP-4-amino-3,4,6-trideoxy- d-mannose are presented. GDP-Perosamine Synthase: Structural Analysis and Production of a Novel Trideoxysugar(,).,Cook PD, Holden HM Biochemistry. 2008 Mar 4;47(9):2833-40. Epub 2008 Feb 5. PMID:18247575[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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