1. Substrate-Triggered Formation of a Peroxo-Fe2(III/III) Intermediate during Fatty Acid Decarboxylation by UndA
- Author
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Zhang, Bo, Rajakovich, Lauren J, Van Cura, Devon, Blaesi, Elizabeth J, Mitchell, Andrew J, Tysoe, Christina R, Zhu, Xuejun, Streit, Bennett R, Rui, Zhe, Zhang, Wenjun, Boal, Amie K, Krebs, Carsten, and Bollinger, J Martin
- Subjects
Decarboxylation ,Iron Compounds ,Oxidoreductases ,Peroxides ,Pseudomonas fluorescens ,Substrate Specificity ,Chemical Sciences ,General Chemistry - Abstract
The iron-dependent oxidase UndA cleaves one C3-H bond and the C1-C2 bond of dodecanoic acid to produce 1-undecene and CO2. A published X-ray crystal structure showed that UndA has a heme-oxygenase-like fold, thus associating it with a structural superfamily that includes known and postulated non-heme diiron proteins, but revealed only a single iron ion in the active site. Mechanisms proposed for initiation of decarboxylation by cleavage of the C3-H bond using a monoiron cofactor to activate O2 necessarily invoked unusual or potentially unfeasible steps. Here we present spectroscopic, crystallographic, and biochemical evidence that the cofactor of Pseudomonas fluorescens Pf-5 UndA is actually a diiron cluster and show that binding of the substrate triggers rapid addition of O2 to the Fe2(II/II) cofactor to produce a transient peroxo-Fe2(III/III) intermediate. The observations of a diiron cofactor and substrate-triggered formation of a peroxo-Fe2(III/III) intermediate suggest a small set of possible mechanisms for O2, C3-H and C1-C2 activation by UndA; these routes obviate the problematic steps of the earlier hypotheses that invoked a single iron.
- Published
- 2019