Structural highlights
Publication Abstract from PubMedThiol dioxygenation is the initial oxidation step that commits a thiol to important catabolic or biosynthetic pathways. The reaction is catalyzed by a family of specific non-heme mononuclear-iron proteins each of which is reported to react efficiently with only one substrate. This family of enzymes includes cysteine dioxygenase, cysteamine dioxygenase, mercaptosuccinate dioxygenase and 3-mercaptopropionate dioxygenase. Using sequence alignment to infer cysteine dioxygenase activity, a cysteine dioxygenase homologue from Pseudomonas aeruginosa (p3MDO) has been identified. Mass spectrometry of P. aeruginosa under standard growth conditions showed p3MDO is expressed in low levels suggesting that this metabolic pathway is available to the organism. Purified recombinant p3MDO is able to oxidize both cysteine and 3-mercaptopropionic acid (3-MPA) in vitro, with a marked preference for 3-MPA. We therefore describe this enzyme as a 3-mercaptopropionate dioxygenase. Mossbauer spectroscopy suggests that substrate binding to the ferrous iron is through the thiol but indicates each substrate could adopt different coordination geometries. Crystallographic comparison with mammalian cysteine dioxygenase shows that the overall active site geometry is conserved but suggests that the different substrate specificity can be related to replacement of an arginine by a glutamine in the active site. The Cysteine Dioxygenase Homologue from Pseudomonas aeruginosa is a 3-Mercaptopropionate Dioxygenase.,Tchesnokov EP, Fellner M, Siakkou E, Kleffmann T, Martin LW, Aloi S, Lamont IL, Wilbanks SM, Jameson GN J Biol Chem. 2015 Aug 13. pii: jbc.M114.635672. PMID:26272617[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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