Publications

• FtmOx1, a non-heme Fe(II) and alpha-ketoglutarate-dependent dioxygenase, catalyses the endoperoxide formation of verruculogen in Aspergillus fumigatus.

  Steffan N., Grundmann A., Afiyatullov S., Ruan H., Li S.M.

  Verruculogen is a tremorgenic mycotoxin and contains an endoperoxide bond. In this study, we describe the cloning, overexpression and purification of a non-heme Fe(ii) and alpha-ketoglutarate-dependent dioxygenase FtmOx1 from Aspergillus fumigatus, which catalyses the conversion of fumitremorgin B ... >> More

  Verruculogen is a tremorgenic mycotoxin and contains an endoperoxide bond. In this study, we describe the cloning, overexpression and purification of a non-heme Fe(ii) and alpha-ketoglutarate-dependent dioxygenase FtmOx1 from Aspergillus fumigatus, which catalyses the conversion of fumitremorgin B to verruculogen by inserting an endoperoxide bond between two prenyl moieties. Incubation with (18)O(2)-enriched atmosphere demonstrated that both oxygen atoms of the endoperoxide bond are derived from one molecule of O(2). FtmOx1 is the first endoperoxide-forming non-heme Fe(ii) and alpha-ketoglutarate-dependent dioxygenase reported so far. A mechanism of FtmOx1-catalysed verruculogen formation is postulated and discussed. << Less

  Org. Biomol. Chem. 7:4082-4087(2009) [PubMed] [EuropePMC]

• Hydrogen Donation but not Abstraction by a Tyrosine (Y68) during Endoperoxide Installation by Verruculogen Synthase (FtmOx1).

  Dunham N.P., Del Rio Pantoja J.M., Zhang B., Rajakovich L.J., Allen B.D., Krebs C., Boal A.K., Bollinger J.M. Jr.

  Hydrogen-atom transfer (HAT) from a substrate carbon to an iron(IV)-oxo (ferryl) intermediate initiates a diverse array of enzymatic transformations. For outcomes other than hydroxylation, coupling of the resultant carbon radical and hydroxo ligand (oxygen rebound) must generally be averted. A rec ... >> More

  Hydrogen-atom transfer (HAT) from a substrate carbon to an iron(IV)-oxo (ferryl) intermediate initiates a diverse array of enzymatic transformations. For outcomes other than hydroxylation, coupling of the resultant carbon radical and hydroxo ligand (oxygen rebound) must generally be averted. A recent study of FtmOx1, a fungal iron(II)- and 2-(oxo)glutarate-dependent oxygenase that installs the endoperoxide of verruculogen by adding O₂ between carbons 21 and 27 of fumitremorgin B, posited that tyrosine (Tyr or Y) 224 serves as HAT intermediary to separate the C21 radical (C21•) and Fe(III)-OH HAT products and prevent rebound. Our reinvestigation of the FtmOx1 mechanism revealed, instead, direct HAT from C21 to the ferryl complex and surprisingly competitive rebound. The C21-hydroxylated (rebound) product, which undergoes deprenylation, predominates when low [O₂] slows C21•-O₂ coupling in the next step of the endoperoxidation pathway. This pathway culminates with addition of the C21-O-O• peroxyl adduct to olefinic C27 followed by HAT to the C26• from a Tyr. The last step results in sequential accumulation of Tyr radicals, which are suppressed without detriment to turnover by inclusion of the reductant, ascorbate. Replacement of each of four candidates for the proximal C26 H• donor (including Y224) with phenylalanine (F) revealed that only the Y68F variant (i) fails to accumulate the first Tyr• and (ii) makes an altered major product, identifying Y68 as the donor. The implied proximities of C21 to the iron cofactor and C26 to Y68 support a new docking model of the enzyme-substrate complex that is consistent with all available data. << Less

  J. Am. Chem. Soc. 141:9964-9979(2019) [PubMed] [EuropePMC]

• Gene disruption and biochemical characterization of verruculogen synthase of Aspergillus fumigatus.

  Kato N., Suzuki H., Takagi H., Uramoto M., Takahashi S., Osada H.

  Chembiochem 12:711-714(2011) [PubMed] [EuropePMC]