title: Structural and biochemical characterization of gentisate 1,2-dioxygenase from Escherichia coli O157:H7.
abstract: Gentisic acid (2,5-dihydroxybenzoic acid) is a key intermediate in aerobic bacterial pathways that are responsible for the metabolism of a large number of aromatic compounds. The critical step of these pathways is the oxygen-dependent reaction catalysed by gentisate 1,2-dioxygenase which opens the aromatic ring of gentisate to form maleylpyruvate. From gentisic acid, the cell derives carbon and energy through the conversion of maleylpyruvate to central metabolites. We have confirmed the annotation of a gentisate 1,2-dioygenase from the pathogenic O157:H7 Escherichia coli strain and present the first structural characterization of this family of enzymes. The identity of the reaction product was revealed using tandem mass spectroscopy. The operon responsible for the degradation of gentisate in this organism exhibits a high degree of conservation with the gentisate-degrading operons of other pathogenic bacteria, including the Shiga toxin-producing E. coli O103:H2, but does not appear to be present in non-pathogenic strains. The acquisition of the gentisate operon may represent a special adaptation to meet carbon source requirements under conditions of environmental stress and may provide a selective advantage for enterohaemorrhagic E. coli relative to their non-pathogenic counterparts.
authors.affiliation: Department of Biochemistry, Queen's University, Kingston, ON, Canada K7L 3N6.
authors.forename: Melanie A
authors.initials: MA
authors.lastname: Adams
authors.forename: Vinay K
authors.initials: VK
authors.lastname: Singh
authors.forename: Bernd O
authors.initials: BO
authors.lastname: Keller
authors.forename: Zongchao
authors.initials: Z
authors.lastname: Jia
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D049308:Dioxygenases / Q000737:chemistry*; D019453:Escherichia coli O157 / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D011487:Protein Conformation
chemical_list: D029968:Escherichia coli Proteins; D049308:Dioxygenases; C026247:gentisate 1,2-dioxygenase