Evidence that the Fosfomycin-Producing Epoxidase, HppE, Is a Non–Heme-Iron Peroxidase

Wang, Chen; Chang, Wei‐chen; Guo, Yisong; Huang, Hui; Peck, Spencer C.; Pandelia, Maria-Eirini; Lin, Geng-Min; Liu, Hung Wen; Krebs, Carsten; Bollinger, J. Martin

doi:10.1126/science.1240373

Cited by 68 publications

(108 citation statements)

References 66 publications

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“…[124] However, it transpired from later experiments that the enzyme is inactive with O2; it hardly even binds it, and it actually employs H2O2 as oxidant. [125] Answering why the QM-cluster calculations failed to detect the flaw in the assumptions would need a separate, higher-level study, but one can expect that the effects of the neglected or approximated environment may be quite significant for the step when O2 is transferred from aqueous solution through the protein cavities to the iron within the active site pocket, and may be less so for the inner-sphere chemistry occurring thereafter. Indeed, the suggested substrate oxidation pathway starting from a FeII-hydroperoxo-iron(II) structure (which was a proposed intermediate of O2…”

Section: Miscellaneous Monoiron Systemsmentioning

confidence: 99%

Mono- and binuclear non-heme iron chemistry from a theoretical perspective

et al. 2016

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In this minireview, we provide an account of the current state-of-the-art developments in the area of mono-and binuclear non-heme enzymes (NHFe and NHFe2) and the smaller NHFe(2) synthetic models, mostly from a theoretical and computational perspective. The sheer complexity, and at the same time the beauty, of the NHFe(2) world represent a challenge for both experimental as well as theoretical methods. We emphasize that the concerted progress on both theoretical and experimental side is a conditio sine qua non for future understanding, exploration and utilization of the NHFe(2) systems.After briefly discussing the current challenges and advances in the computational methodology, we review the recent spectroscopic and computational studies of NHFe(2) enzymatic and inorganic systems and highlight the correlations between various experimental data (spectroscopic, kinetic, thermodynamic, electrochemical) and computations. Throughout, we attempt to keep in mind the most fascinating and attractive phenomenon in the NHFe(2) chemistry which is the fact that despite the strong oxidative power of many reactive intermediates, the NHFe(2) enzymes perform catalysis with high selectivity. We conclude with our personal viewpoint and hope that further developments in quantum chemistry and especially in the field of multireference wave function methods are needed to have a solid theoretical basis for the NHFe(2) studies, mostly by providing benchmarking and calibration of the computationally efficient and easy-to-use DFT methods.

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Section: Miscellaneous Monoiron Systemsmentioning

confidence: 99%

Mono- and binuclear non-heme iron chemistry from a theoretical perspective

et al. 2016

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“…Because HppE, a long recognized nonheme iron (II) oxidase, was recently characterized to be a peroxidase (22) in situ inhibited 1-undecene production by UndA, but the addition of dithionite increased the rate of HppE up to 1,000 times (22).…”

Section: Significancementioning

confidence: 99%

Microbial biosynthesis of medium-chain 1-alkenes by a nonheme iron oxidase

Rui

Zhu

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

189

233

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Aliphatic medium-chain 1-alkenes (MCAEs, ∼10 carbons) are "drop-in" compatible next-generation fuels and precursors to commodity chemicals. Mass production of MCAEs from renewable resources holds promise for mitigating dependence on fossil hydrocarbons. An MCAE, such as 1-undecene, is naturally produced by Pseudomonas as a semivolatile metabolite through an unknown biosynthetic pathway. We describe here the discovery of a single gene conserved in Pseudomonas responsible for 1-undecene biosynthesis. The encoded enzyme is able to convert medium-chain fatty acids (C10-C14) into their corresponding terminal olefins using an oxygen-activating, nonheme iron-dependent mechanism. Both biochemical and X-ray crystal structural analyses suggest an unusual mechanism of β-hydrogen abstraction during fatty acid substrate activation. Our discovery unveils previously unidentified chemistry in the nonheme Fe(II) enzyme family, provides an opportunity to explore the biology of 1-undecene in Pseudomonas, and paves the way for tailored bioconversion of renewable raw materials to MCAE-based biofuels and chemical commodities.urging energy consumption and environmental concerns have stimulated interest in the production of chemicals and fuels through sustainable and renewable approaches. Medium-chain 1-alkenes (MCAEs) are of particular interest because they are "drop-in"-ready next-generation fuels with superior properties such as low freezing point compared with long-chain diesels, high energy content compared with short-chain fuels, easy product recovery due to insolubility in water, and compatibility with the existing engine systems and transportation infrastructure (1, 2). Because of a readily derivatized terminal functionality, MCAEs are also valuable precursors to commodity chemicals such as lubricants, pesticides, polymers, and detergents (3, 4). Biological production of MCAEs from renewable resources holds promise for mitigating dependence on fossil hydrocarbons. Although MCAEs are naturally produced by diverse species as semivolatile metabolites (5, 6), little is known about the genetic and molecular basis for MCAE biosynthesis. Elucidation of MCAE biosynthetic pathway will serve as the basis for engineering efforts to establish bioprocesses for producing MCAE-based biofuels and chemical commodities from renewable resources.1-Undecene, an MCAE with 11 carbons, was identified as a biomarker of Pseudomonas aeruginosa, one of the most significant human pathogens (7-10). However, the biology of this characteristic semivolatile metabolite in P. aeruginosa remains enigmatic, and the biosynthetic pathway of 1-undecene has not previously been explored. It was also reported that some species of Pseudomonas produce 1-undecene, whereas some species do not (8), inspiring us to use a comparative genomics approach to reveal the genetic basis for 1-undecene biosynthesis (11). It is notable that one of the major challenges for MCAE biosynthetic study is the detection and quantification of MCAE production. MCAEs, such as 1-undecene, are only ...

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“…Indeed, this mechanism was recently proposed for closure of the epoxide ring in the antibiotic fosfomycin by ( S )-2-hydroxypropylphosphonate epoxidase (HppE). 44,45 Among the evidence cited for this mechanism was the inversion of configuration at C1 during ring closure. This example shows that the stereochemistry of H • abstraction and C–O coupling is a crucial mechanistic issue in the oxacyclization reactions.…”

Section: Resultsmentioning

confidence: 99%

Installation of the Ether Bridge of Lolines by the Iron- and 2-Oxoglutarate-Dependent Oxygenase, LolO: Regio- and Stereochemistry of Sequential Hydroxylation and Oxacyclization Reactions

et al. 2018

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The core of the loline family of insecticidal alkaloids is the bicyclic pyrrolizidine unit with an additional strained ether bridge between carbons 2 and 7. Previously reported genetic and in vivo biochemical analyses showed that the presumptive iron- and 2-oxoglutarate-dependent (Fe/2OG) oxygenase, LolO, is required for installation of the ether bridge upon the pathway intermediate, 1-exo-acetamidopyrrolizidine (AcAP). Here we show that LolO is, in fact, solely responsible for this biosynthetic four-electron oxidation. In sequential 2OG- and O2-consuming steps, LolO removes hydrogens from C2 and C7 of AcAP to form both carbon–oxygen bonds in N-acetylnorloline (NANL), the precursor to all other lolines. When supplied with substoichiometric 2OG, LolO only hydroxylates AcAP. At higher 2OG:AcAP ratios, the enzyme further processes the alcohol to the tricyclic NANL. Characterization of the alcohol intermediate by mass spectrometry and nuclear magnetic resonance spectroscopy shows that it is 2-endo-hydroxy-1-exo-acetamidopyrrolizidine (2-endo-OH-AcAP). Kinetic and spectroscopic analyses of reactions with site-specifically deuteriated AcAP substrates confirm that the C2–H bond is cleaved first and that the responsible intermediate is, as expected, an FeIV–oxo (ferryl) complex. Analyses of the loline products from cultures fed with stereospecifically deuteriated AcAP precursors, proline and aspartic acid, establish that LolO removes the endo hydrogens from C2 and C7 and forms both new C–O bonds with retention of configuration. These findings delineate the pathway to an important class of natural insecticides and lay the foundation for mechanistic dissection of the chemically challenging oxacyclization reaction.

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Evidence that the Fosfomycin-Producing Epoxidase, HppE, Is a Non–Heme-Iron Peroxidase

Cited by 68 publications

References 66 publications

Mono- and binuclear non-heme iron chemistry from a theoretical perspective

Mono- and binuclear non-heme iron chemistry from a theoretical perspective

Microbial biosynthesis of medium-chain 1-alkenes by a nonheme iron oxidase

Installation of the Ether Bridge of Lolines by the Iron- and 2-Oxoglutarate-Dependent Oxygenase, LolO: Regio- and Stereochemistry of Sequential Hydroxylation and Oxacyclization Reactions

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