Structure of a Ferryl Mimic in the Archetypal Iron(II)- And 2-(Oxo)-glutarate-Dependent Dioxygenase, TauD

Katherine M. Davis, Madison Altmyer, Ryan J. Martinie, Irene Schaperdoth, Carsten Krebs, J. Martin Bollinger, Amie K. Boal

Research output: Contribution to journalArticle

Abstract

Iron(II)- and 2-(oxo)-glutarate-dependent (Fe/2OG) oxygenases catalyze a diverse array of oxidation reactions via a common iron(IV)-oxo (ferryl) intermediate. Although the intermediate has been characterized spectroscopically, its short lifetime has precluded crystallograhic characterization. In solution, the ferryl was first observed directly in the archetypal Fe/2OG hydroxylase, taurine:2OG dioxygenase (TauD). Here, we substitute the iron cofactor of TauD with the stable vanadium(IV)-oxo (vanadyl) ion to obtain crystal structures mimicking the key ferryl complex. Intriguingly, whereas the structure of the TauD·(VIV-oxo)·succinate·taurine complex exhibits the expected orientation of the VO bond - trans to the His255 ligand and toward the C-H bond to be cleaved, in what has been termed the in-line configuration - the TauD·(VIV-oxo) binary complex is best modeled with its oxo ligand trans to Asp101. This off-line-like configuration is similar to one recently posited as a means to avoid hydroxylation in Fe/2OG enzymes that direct other outcomes, though neither has been visualized in an Fe/2OG structure to date. Whereas an off-line (trans to the proximal His) or off-line-like (trans to the carboxylate ligand) ferryl is unlikely to be important in the hydroxylation reaction of TauD, the observation that the ferryl may deviate from an in-line orientation in the absence of the primary substrate may explain the enzyme's mysterious self-hydroxylation behavior, should the oxo ligand lie trans to His99. This finding reinforces the potential for analogous functional off-line oxo configurations in halogenases, desaturases, and/or cyclases.

Original languageEnglish (US)
Pages (from-to)4218-4223
Number of pages6
JournalBiochemistry
Volume58
Issue number41
DOIs
StatePublished - Oct 15 2019

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Glutarates
Dioxygenases
Taurine
Iron
Hydroxylation
Ligands
Oxygenases
Vanadium
Vanadates
Enzymes
Mixed Function Oxygenases
Crystal structure
tebufenozide
Ions
Oxidation
Substrates

All Science Journal Classification (ASJC) codes

  • Biochemistry

Cite this

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title = "Structure of a Ferryl Mimic in the Archetypal Iron(II)- And 2-(Oxo)-glutarate-Dependent Dioxygenase, TauD",
abstract = "Iron(II)- and 2-(oxo)-glutarate-dependent (Fe/2OG) oxygenases catalyze a diverse array of oxidation reactions via a common iron(IV)-oxo (ferryl) intermediate. Although the intermediate has been characterized spectroscopically, its short lifetime has precluded crystallograhic characterization. In solution, the ferryl was first observed directly in the archetypal Fe/2OG hydroxylase, taurine:2OG dioxygenase (TauD). Here, we substitute the iron cofactor of TauD with the stable vanadium(IV)-oxo (vanadyl) ion to obtain crystal structures mimicking the key ferryl complex. Intriguingly, whereas the structure of the TauD·(VIV-oxo)·succinate·taurine complex exhibits the expected orientation of the VO bond - trans to the His255 ligand and toward the C-H bond to be cleaved, in what has been termed the in-line configuration - the TauD·(VIV-oxo) binary complex is best modeled with its oxo ligand trans to Asp101. This off-line-like configuration is similar to one recently posited as a means to avoid hydroxylation in Fe/2OG enzymes that direct other outcomes, though neither has been visualized in an Fe/2OG structure to date. Whereas an off-line (trans to the proximal His) or off-line-like (trans to the carboxylate ligand) ferryl is unlikely to be important in the hydroxylation reaction of TauD, the observation that the ferryl may deviate from an in-line orientation in the absence of the primary substrate may explain the enzyme's mysterious self-hydroxylation behavior, should the oxo ligand lie trans to His99. This finding reinforces the potential for analogous functional off-line oxo configurations in halogenases, desaturases, and/or cyclases.",
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Structure of a Ferryl Mimic in the Archetypal Iron(II)- And 2-(Oxo)-glutarate-Dependent Dioxygenase, TauD. / Davis, Katherine M.; Altmyer, Madison; Martinie, Ryan J.; Schaperdoth, Irene; Krebs, Carsten; Bollinger, J. Martin; Boal, Amie K.

In: Biochemistry, Vol. 58, No. 41, 15.10.2019, p. 4218-4223.

Research output: Contribution to journalArticle

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T1 - Structure of a Ferryl Mimic in the Archetypal Iron(II)- And 2-(Oxo)-glutarate-Dependent Dioxygenase, TauD

AU - Davis, Katherine M.

AU - Altmyer, Madison

AU - Martinie, Ryan J.

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AU - Boal, Amie K.

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AB - Iron(II)- and 2-(oxo)-glutarate-dependent (Fe/2OG) oxygenases catalyze a diverse array of oxidation reactions via a common iron(IV)-oxo (ferryl) intermediate. Although the intermediate has been characterized spectroscopically, its short lifetime has precluded crystallograhic characterization. In solution, the ferryl was first observed directly in the archetypal Fe/2OG hydroxylase, taurine:2OG dioxygenase (TauD). Here, we substitute the iron cofactor of TauD with the stable vanadium(IV)-oxo (vanadyl) ion to obtain crystal structures mimicking the key ferryl complex. Intriguingly, whereas the structure of the TauD·(VIV-oxo)·succinate·taurine complex exhibits the expected orientation of the VO bond - trans to the His255 ligand and toward the C-H bond to be cleaved, in what has been termed the in-line configuration - the TauD·(VIV-oxo) binary complex is best modeled with its oxo ligand trans to Asp101. This off-line-like configuration is similar to one recently posited as a means to avoid hydroxylation in Fe/2OG enzymes that direct other outcomes, though neither has been visualized in an Fe/2OG structure to date. Whereas an off-line (trans to the proximal His) or off-line-like (trans to the carboxylate ligand) ferryl is unlikely to be important in the hydroxylation reaction of TauD, the observation that the ferryl may deviate from an in-line orientation in the absence of the primary substrate may explain the enzyme's mysterious self-hydroxylation behavior, should the oxo ligand lie trans to His99. This finding reinforces the potential for analogous functional off-line oxo configurations in halogenases, desaturases, and/or cyclases.

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