Crystallization and preliminary X-ray diffraction studies of a monooxygenase from<i>Streptomyces coelicolor</i>A3(2) involved in the biosynthesis of the polyketide actinorhodin

Kendrew, Steven G.; Federici, L.; Savino, C.; Miele, A.E.; Marsh, E. Neil G.; Vallone, B.

doi:10.1107/s0907444900001189

Cited by 8 publications

(9 citation statements)

References 13 publications

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“…The protein fold aligned well with that of the monooxygenase ActVA-Orf6 from S. coelicolor with an overall root mean square deviation of 1.9 Å, despite only 19% sequence identity. Most interesting was the structural alignment of the Trp-66 residue, one of which is strictly conserved across all members of this functional group and thought to play an important role in catalysis (14,15,28). The maintenance of ␤-turn topology in both QuMo and ActVA-Orf6 highlights the minimal effect of low sequence identity on the conservation of global protein fold.…”

Section: Discussionmentioning

confidence: 99%

“…Rather, the side chains of helix A1 and strand B2 close the posterior of the QuMo active site. The studies of ActVA-Orf6 have implied that the enzyme does not require a metal ion or prosthetic group for catalysis (14,15,28). This is also the case for QuMo and likely for other monooxygenases of this family.…”

Section: Three-dimensional Fold Of Qumo Suggests That It Is a Monooxymentioning

confidence: 93%

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Structural and Biochemical Evidence for an Enzymatic Quinone Redox Cycle in Escherichia coli

Adams¹,

Jia

2005

Journal of Biological Chemistry

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Naturally synthesized quinones perform a variety of important cellular functions. Escherichia coli produce both ubiquinone and menaquinone, which are involved in electron transport. However, semiquinone intermediates produced during the one-electron reduction of these compounds, as well as through auto-oxidation of the hydroxyquinone product, generate reactive oxygen species that stress the cell. Here, we present the crystal structure of YgiN, a protein of hitherto unknown function. The three-dimensional fold of YgiN is similar to that of ActVA-Orf6 monooxygenase, which acts on hydroxyquinone substrates. YgiN shares a promoter with "modulator of drug activity B," a protein with activity similar to that of mammalian DT-diaphorase capable of reducing mendione. YgiN was able to reoxidize menadiol, the product of the "modulator of drug activity B" (MdaB) enzymatic reaction. We therefore refer to YgiN as quinol monooxygenase. Modulator of drug activity B is reported to be involved in the protection of cells from reactive oxygen species formed during single electron oxidation and reduction reactions. The enzymatic activities, together with the structural characterization of YgiN, lend evidence to the possible existence of a novel quinone redox cycle in E. coli.

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Section: Discussionmentioning

confidence: 99%

Section: Three-dimensional Fold Of Qumo Suggests That It Is a Monooxymentioning

confidence: 93%

Structural and Biochemical Evidence for an Enzymatic Quinone Redox Cycle in Escherichia coli

Adams¹,

Jia

2005

Journal of Biological Chemistry

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“…Our work has focused on the enzymes catalysing oxygenations of polyketide biosynthetic pathways, particularly those catalysing the oxidations that introduce hydroxy‐ or quinone functionality to type II aromatic polyketides. ActVA‐Orf6 was characterized as a monooxygenase (Kendrew et al ., 1997, 2000) from the actinorhodin pathway that catalyses the oxidation of phenolic compounds to the corresponding quinone. The reaction catalysed in vivo by ActVA‐Orf6 (Figure 1) is the conversion of 6‐deoxydihydrokalafungin (6‐DDHK) to dihydrokalafungin (DHK), intermediates in the biosynthesis of actinorhodin.…”

Section: Introductionmentioning

confidence: 99%

The structure of ActVA-Orf6, a novel type of monooxygenase involved in actinorhodin biosynthesis

Sciara¹,

et al. 2003

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ActVA-Orf6 monooxygenase from Streptomyces coelicolor that catalyses the oxidation of an aromatic intermediate of the actinorhodin biosynthetic pathway is a member of a class of small monooxygenases that carry out oxygenation without the assistance of any of the prosthetic groups, metal ions or cofactors normally associated with activation of molecular oxygen. The overall structure is a ferredoxin-like fold with a novel dimeric assembly, indicating that the widely represented ferredoxin fold may sustain yet another functionality. The resolution (1.3 A Ê ) of the enzyme structure and its complex with substrate and product analogues allows us to visualize the mechanism of binding and activation of the substrate for attack by molecular oxygen, and utilization of two gates for the reaction components including a proton gate and an O 2 /H 2 O gate with a putative protein channel. This is the ®rst crystal structure of an enzyme involved in the tailoring of a type II aromatic polyketide and illustrates some of the enzyme±substrate recognition features that may apply to a range of other enzymes involved in modifying a polyketide core structure.

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“…The antibiotic biosynthesis monooxygenase family (ABMs, 2 Pfam family PF03992) contains several small, structurally simple, and intrinsically solvent-and temperature-stable enzymes known to catalyze O 2 -dependent and cofactor-independent oxidations or monooxygenations (5)(6)(7)(8)(11)(12)(13)(14)(15). Many ABMs are part of the biosynthetic pathways for polyketide antibiotics, including tetracenomycin (14,16), daunomycin (17), actinorhodin (8,12), alnumycin (18), and aclacinomycin (11), also known as nogalamycin (19).…”

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confidence: 99%

Monooxygenase Substrates Mimic Flavin to Catalyze Cofactorless Oxygenations

Machovina

Usselman

DuBois

2016

Journal of Biological Chemistry

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Members of the antibiotic biosynthesis monooxygenase family catalyze O 2 -dependent oxidations and oxygenations in the absence of any metallo-or organic cofactor. How these enzymes surmount the kinetic barrier to reactions between singlet substrates and triplet O 2 is unclear, but the reactions have been proposed to occur via a flavin-like mechanism, where the substrate acts in lieu of a flavin cofactor. To test this model, we monitored the uncatalyzed and enzymatic reactions of dithranol, a substrate for the nogalamycin monooxygenase (NMO) from Streptomyces nogalater. As with flavin, dithranol oxidation was faster at a higher pH, although the reaction did not appear to be base-catalyzed. Rather, conserved asparagines contributed to suppression of the substrate pK a . The same residues were critical for enzymatic catalysis that, consistent with the flavoenzyme model, occurred via an O 2 -dependent slow step. Evidence for a superoxide/substrate radical pair intermediate came from detection of enzyme-bound superoxide during turnover. Small molecule and enzymatic superoxide traps suppressed formation of the oxygenation product under uncatalyzed conditions, whereas only the small molecule trap had an effect in the presence of NMO. This suggested that NMO both accelerated the formation and directed the recombination of a superoxide/dithranyl radical pair. These catalytic strategies are in some ways flavin-like and stand in contrast to the mechanisms of urate oxidase and (1H)-3-hydroxy-4-oxoquinaldine 2,4-dioxygenase, both cofactor-independent enzymes that surmount the barriers to direct substrate/O 2 reactivity via markedly different means.

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Crystallization and preliminary X-ray diffraction studies of a monooxygenase fromStreptomyces coelicolorA3(2) involved in the biosynthesis of the polyketide actinorhodin

Cited by 8 publications

References 13 publications

Structural and Biochemical Evidence for an Enzymatic Quinone Redox Cycle in Escherichia coli

Structural and Biochemical Evidence for an Enzymatic Quinone Redox Cycle in Escherichia coli

The structure of ActVA-Orf6, a novel type of monooxygenase involved in actinorhodin biosynthesis

Monooxygenase Substrates Mimic Flavin to Catalyze Cofactorless Oxygenations

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