Discovery, characterization, and metabolic engineering of Rieske non-heme iron monooxygenases for guaiacol O-demethylation

Bleem, Alissa; Kuatsjah, Eugene; Presley, Gerald N.; Hinchen, D.J.; Zahn, Michael; Garcia, David; Michener, William E.; König, Gerhard; Tornesakis, Konstantinos; Allemann, Marco N.; Giannone, Richard J.; McGeehan, J.E.; Beckham, Gregg T.; Michener, Josh

doi:10.1016/j.checat.2022.04.019

Cited by 13 publications

(16 citation statements)

References 96 publications

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“…As such, it was confirmed that SwGdmB productively partnered Adapted from Michener and co-workers. 5 not only with NaGdmA, but also with the two other ROs in vitro. For all GdmA enzymes, the specific activities were determined and the substrate scope toward a range of lignin-derived aromatics was investigated.…”

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confidence: 87%

“…The study by Michener and co-workers in this issue of Chem Catalysis fills this gap with a Rieske-type guaiacol O-demethylase from Novosphingobium aromaticivorans DSM12444 (NaGdmA) and several homologs from other bacteria. 5 In an earlier study, Michener and coworkers evolved N. aromaticivorans DSM12444 to rapidly grow on guaiacylglycerol-b-guaiacyl ether (GGE) as the sole carbon source. 10 Notably, this strain also acquired the ability to grow on guaia-col.…”

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confidence: 99%

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Expanding the repertoire of Rieske oxygenases for O-demethylations

Schmidt

2022

Chem Catalysis

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confidence: 87%

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confidence: 99%

Expanding the repertoire of Rieske oxygenases for O-demethylations

Schmidt

2022

Chem Catalysis

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“…Rieske-type oxygenases are a class of non-heme iron enzymes widely distributed in nature. − The most well-characterized Rieske-type reactions are those involved in the degradation of aromatic compounds. , In recent years, several Rieske-type oxygenases in natural product biosynthetic pathways were reported, including RedG/McpG-catalyzed cyclization in prodiginine biosynthesis, arylamine oxidation in pyrrolnitrin biosynthesis, the oxidation of chlorophyll a to chlorophyll b by chlorophyllide a oxygenase, hydroxylation of salvigenin by flavone-8-hydroxylase, steroid metabolism, guaiacol O -demethylation, several steps in the biosynthesis of shellfish toxin saxitoxin, paralytic shellfish toxin, and azomycin biosynthesis. , …”

Section: Introductionmentioning

confidence: 99%

Light-Driven Oxidative Demethylation Reaction Catalyzed by a Rieske-Type Non-heme Iron Enzyme Stc2

Weitz

et al. 2022

ACS Catal.

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Rieske-type non-heme iron oxygenases/oxidases catalyze a wide range of transformations. Their applications in bioremediation or biocatalysis face two key barriers: the need of expensive NAD(P)H as a reductant and a proper reductase to mediate the electron transfer from NAD(P)H to the oxygenases. To bypass the need of both the reductase and NAD(P)H, using Rieske-type oxygenase (Stc2)-catalyzed oxidative demethylation as the model system, we report Stc2 photocatalysis using eosin Y/sulfite as the photosensitizer/sacrificial reagent pair. In a flow-chemistry setting to separate the photo-reduction half-reaction and oxidation half-reaction, Stc2 photo-biocatalysis outperforms the Stc2-NAD(P)H-reductase (GbcB) system. In addition, in a few other selected Rieske enzymes (NdmA, CntA, and GbcA) and a flavin-dependent enzyme (iodotyrosine deiodinase, IYD), the eosin Y/sodium sulfite photo-reduction pair could also serve as the NAD(P)H-reductase surrogate to support catalysis, which implies the potential applicability of this photo-reduction system to other redox enzymes.

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“…More recently, attention has turned to the Rieske monooxygenase class, members of which fall into several subclasses that catalyze hydroxylation of aromatic, ,, cyclic, , and aliphatic ,,, substrates. Additionally, hydroxylation of heteroatoms, dehydrogenation, desaturation, and O- and N- demethylation ,,,− of numerous environmentally relevant or economically valuable substrates have been reported. ,, Our studies have focused on salicylate 5-hydroxylase (S5H), which catalyzes the formation of gentisate (2,5-dihydroxybenzoate) as part of one of the naphthalene biodegradation pathways in Ralstonia. , The hydroxylase component (S5HH) of the three-component S5H system (reductase, ferredoxin, and hydroxylase) appears to catalyze strictly monooxygenase chemistry, while conserving both the α 3 β 3 quaternary structure and metal cofactors of Rieske dioxygenases. ,− The initial studies of the S5HH mechanism surprisingly showed that the rate constant for electron transfer from the Rieske cluster when benzoate was used as the substrate in place of salicylate was slowed approximately 20-fold. Thus, the reaction exhibited the same dependence on the specific structure and electronic characteristics of the substrate as described for the Rieske dioxygenases. , A very similar mechanism was proposed based on initial attack by an Fe(III)-superoxo species (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

Contrasting Mechanisms of Aromatic and Aryl-Methyl Substituent Hydroxylation by the Rieske Monooxygenase Salicylate 5-Hydroxylase

et al. 2022

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The hydroxylase component (S5HH) of salicylate-5-hydroxylase catalyzes C5 ring hydroxylation of salicylate but switches to methyl hydroxylation when a C5 methyl substituent is present. The use of 18 O 2 reveals that both aromatic and aryl-methyl hydroxylations result from monooxygenase chemistry. The functional unit of S5HH comprises a nonheme Fe(II) site located 12 Å across a subunit boundary from a one-electron reduced Riesketype iron−sulfur cluster. Past studies determined that substrates bind near the Fe(II), followed by O 2 binding to the iron to initiate catalysis. Stopped-flow-single-turnover reactions (STOs) demonstrated that the Rieske cluster transfers an electron to the iron site during catalysis. It is shown here that fluorine ring substituents decrease the rate constant for Rieske electron transfer, implying a prior reaction of an Fe(III)-superoxo intermediate with a substrate. We propose that the iron becomes fully oxidized in the resulting Fe(III)-peroxo-substrate-radical intermediate, allowing Rieske electron transfer to occur. STO using 5-CD 3 -salicylate-d 8 occurs with an inverse kinetic isotope effect (KIE). In contrast, STO of a 1:1 mixture of unlabeled and 5-CD 3 -salicylate-d 8 yields a normal product isotope effect. It is proposed that aromatic and aryl-methyl hydroxylation reactions both begin with the Fe(III)-superoxo reaction with a ring carbon, yielding the inverse KIE due to sp 2 → sp 3 carbon hybridization. After Rieske electron transfer, the resulting Fe(III)-peroxo-salicylate intermediate can continue to aromatic hydroxylation, whereas the equivalent aryl-methyl intermediate formation must be reversible to allow the substrate exchange necessary to yield a normal product isotope effect. The resulting Fe(III)-(hydro)peroxo intermediate may be reactive or evolve through a high-valent iron intermediate to complete the arylmethyl hydroxylation.

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Discovery, characterization, and metabolic engineering of Rieske non-heme iron monooxygenases for guaiacol O-demethylation

Cited by 13 publications

References 96 publications

Expanding the repertoire of Rieske oxygenases for O-demethylations

Expanding the repertoire of Rieske oxygenases for O-demethylations

Light-Driven Oxidative Demethylation Reaction Catalyzed by a Rieske-Type Non-heme Iron Enzyme Stc2

Contrasting Mechanisms of Aromatic and Aryl-Methyl Substituent Hydroxylation by the Rieske Monooxygenase Salicylate 5-Hydroxylase

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