title: Discovery that the assembly of the dipyrromethane cofactor of porphobilinogen deaminase holoenzyme proceeds initially by the reaction of preuroporphyrinogen with the apoenzyme.
abstract: The assembly process of the dipyrromethane cofactor of Escherichia coli porphobilinogen deaminase holoenzyme is initiated by the reaction of the porphobilinogen deaminase apoenzyme with preuroporphyrinogen. The resulting enzyme-bound tetrapyrrole (bilane) is equivalent to the holoenzyme intermediate complex ES2 and yields the dipyrromethane cofactor by reactions of the normal catalytic cycle. These observations indicate that preuroporphyrinogen, rather than porphobilinogen, is the preferred precursor for the dipyrromethane cofactor and explain the existence of the D84A and D84N deaminase mutants as catalytically inactive ES2 complexes.
authors.affiliation: Biochemistry Department, School of Biological Sciences, University of Southampton, U.K.
authors.forename: P M
authors.initials: PM
authors.lastname: Shoolingin-Jordan
authors.forename: M J
authors.initials: MJ
authors.lastname: Warren
authors.forename: S J
authors.initials: SJ
authors.lastname: Awan
mesh_terms: D001051:Apoenzymes / Q000378:metabolism; D003067:Coenzymes / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D015870:Gene Expression; D011163:Hydroxymethylbilane Synthase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D009154:Mutation / Q000235:genetics; D011162:Porphobilinogen / Q000378:metabolism*; D014577:Uroporphyrinogens / Q000378:metabolism*
chemical_list: D001051:Apoenzymes; D003067:Coenzymes; D014577:Uroporphyrinogens; C056776:dipyrromethane cofactor; C024393:hydroxymethylbilane; D011162:Porphobilinogen; D011163:Hydroxymethylbilane Synthase; D003545:Cysteine