3BN1

Crystal structure of GDP-perosamine synthase

Summary for 3BN1

• Entry DOI: 10.2210/pdb3bn1/pdb
• Descriptor: Perosamine synthetase, ACETATE ION, SODIUM ION, ... (5 entities in total)
• Functional Keywords: perosamine, aspartate aminotransferase, deoxysugar, o-antigen, transferase
• Biological source: Caulobacter crescentus
• Total number of polymer chains: 4
• Total formula weight: 164645.56

Authors

Cook, P.D.,Holden, H.M. (deposition date: 2007-12-13, release date: 2008-03-18, Last modification date: 2023-11-15)

Primary citation

Cook, P.D.,Holden, H.M.
GDP-Perosamine Synthase: Structural Analysis and Production of a Novel Trideoxysugar
Biochemistry, 47:2833-2840, 2008

PubMed Abstract: Perosamine 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.

PubMed: 18247575
DOI: 10.1021/bi702430d

Experimental method

X-RAY DIFFRACTION (1.8 Å)