A Complex of 2‐Hydroxyisocaproyl‐Coenzyme A Dehydratase and its Activator from <i>Clostridium difficile</i> Stabilized by Aluminium Tetrafluoride‐Adenosine Diphosphate

Kim, Jihoe; Pierik, Antonio J.

doi:10.1002/cphc.200900876

Cited by 11 publications

(17 citation statements)

References 32 publications

(58 reference statements)

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“…A permanent tight complex between the ATP-dependent activator and the ring reductase components is apparently beneficial for stoichiometric electron transfer in class I BCRs. In contrast, such a tight complex has been reported to be nonproductive in an artificially generated complex between an activator and a dehydratase . This finding fits to the functions of activator components in HADs to catalyze catalytic but never a stoichiometric electron transfer.…”

Section: Discussionsupporting

confidence: 65%

ATP-Dependent Electron Activation Module of Benzoyl-Coenzyme A Reductase from the Hyperthermophilic Archaeon Ferroglobus placidus

et al. 2016

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The class I benzoyl-coenzyme A (BzCoA) reductases (BCRs) are key enzymes in the anaerobic degradation of aromatic compounds that catalyze the ATP-dependent dearomatization of their substrate to a cyclic dienoyl-CoA. The phylogenetically distinct Thauera- and Azoarcus-type BCR subclasses are iron-sulfur enzymes and consist of an ATP-hydrolyzing electron activation module and a BzCoA reduction module. More than 20 years after their initial identification, all biochemical information about class I BCRs derives from studies of the wild-type enzyme from the denitrifying bacterium Thauera aromatica (BCR). Here, we describe the first heterologous production and purification of the ATP-hydrolyzing, electron-activating module of an Azoarcus-type BCR from the hyperthermophilic archaeon Ferroglobus placidus, BzdPQ. The Fe content, UV/vis spectroscopic, and Mössbauer spectroscopic properties of the Fe-enriched enzyme clearly identified a [4Fe-4S] cluster with a redox potential (E°') of -376 mV as a cofactor. ATP hydrolysis is required to overcome a redox barrier of ∼250 mV for stoichiometric electron transfer from the [4Fe-4S] cluster to the substrate benzene ring (E°' = -622 mV). BzdPQ exhibited ATPase activity (15 nmol min mg; K = 270 μM) at 75 °C, which was relatively stable in air in contrast to BCR. The results obtained revealed high levels of functional and molecular similarity between Azoarcus-type BCRs and the homologous ATP-dependent activator components of 2-hydroxyacyl-CoA dehydratases involved in amino acid fermentations. Insights into the diversity and evolution of ATP-dependent electron-activating modules for catalytic or stoichiometric low-potential electron transfer processes are presented.

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Section: Discussionsupporting

confidence: 65%

ATP-Dependent Electron Activation Module of Benzoyl-Coenzyme A Reductase from the Hyperthermophilic Archaeon Ferroglobus placidus

et al. 2016

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“…In the presence of ADP and AlF 4 – , a similar complex, HadBCI 2 –ADP–AlF 4 – , could be obtained. The stable complex was isolated by size exclusion chromatography, affinity chromatography, or ultrafiltration . Unfortunately, no crystallization trials were performed.…”

Section: Ketyls By Enzymatic One-electron Reduction Of the Ketone-lik...mentioning

confidence: 99%

“…The stable complex was isolated by size exclusion chromatography, affinity chromatography, or ultra- filtration. 32 Unfortunately, no crystallization trials were performed. Another similarity between NifH and HgdC/ HadI is the property of their clusters.…”

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confidence: 99%

Enzymatic Reactions Involving Ketyls: From a Chemical Curiosity to a General Biochemical Mechanism

Buckel

2019

Biochemistry

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Ketyls are radical anions with nucleophilic properties. Ketyls obtained by enzymatic one-electron reduction of thioesters were proposed as intermediates for the dehydration of (R)-2hydroxyacyl-CoA to (E)-2-enoyl-CoA. This concept was extended to the Birch-like reduction of benzoyl-CoA to 1,5-cyclohexadienecarboxyl-CoA. Nature uses two methods to achieve the therefore required low reduction potentials of less than −600 mV, either by an ATPdriven electron transfer similar to that catalyzed by the iron protein of nitrogenase or by electron bifurcation. Ketyls formed by thiyl radicalinitiated oxidation of alcohols followed by deprotonation are involved in coenzyme B 12 -independent diol dehydratases, other glycyl radical enzymes mediating key reactions in the degradations of choline, taurine, and 4-hydroxyproline, and all three classes of ribonucleotide reductases. A special case is the dehydration of 4hydroxybutyryl-CoA to crotonyl-CoA, which most likely proceeds via an oxidation to an allylic ketyl but requires neither a strong reductant nor an external radical generator. ■ KETYLS IN ORGANIC CHEMISTRYKetyls are radical anions, whichas the name impliesare derived from ketones by insertion of one electron into the antibonding 2p z orbital of the carbonyl group. 1 Two resonance structures contribute to the stability of a ketyl, the radical at carbon and the negative charge at oxygen and vice versa (Figure 1). Because the oxygen is more electronegative than

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“…The catalytic systems are composed of the two principal components, the electron donor, a dimeric ASKHA‐type ATPase and the catalytic unit, formed by two homologous subunits, each containing a [4Fe4S] cluster that bind the CoA‐substrate and harbor the active site. Complexes between the two components may be stable (some benzoyl‐CoA reductases) or may depend on the nucleotide bound in the ATPase module, as shown for 2‐hydroxyisocaproyl‐CoA dehydratase …”

Section: Introductionmentioning

confidence: 99%

Double‐Cubane [8Fe9S] Clusters: A Novel Nitrogenase‐Related Cofactor in Biology

2020

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Three different types of electron-transferring metallo-ATPases are able to couple ATP hydrolysis to the reduction of lowpotential metal sites, thereby energizing an electron. Besides the Fe-protein known from nitrogenase and homologous enzymes, two other kinds of ATPase with different scaffolds and cofactors are used to achieve a unidirectional, energetic, uphill electron transfer to either reduce inactive Co-corrinoid-containing proteins (RACE-type activators) or a second iron-sulfur cluster-containing enzyme of a unique radical enzymes family (archerases). We have found a new cofactor in the latter enzyme family, that is, a double-cubane cluster with two [4Fe4S] subclusters bridged by a sulfido ligand. An enzyme containing this cofactor catalyzes the ATP-dependent reduction of small molecules, including acetylene. Thus, enzymes containing the double-cubane cofactor are analogous in function and share some structural features with nitrogenases.

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A Complex of 2‐Hydroxyisocaproyl‐Coenzyme A Dehydratase and its Activator from Clostridium difficile Stabilized by Aluminium Tetrafluoride‐Adenosine Diphosphate

Cited by 11 publications

References 32 publications

ATP-Dependent Electron Activation Module of Benzoyl-Coenzyme A Reductase from the Hyperthermophilic Archaeon Ferroglobus placidus

ATP-Dependent Electron Activation Module of Benzoyl-Coenzyme A Reductase from the Hyperthermophilic Archaeon Ferroglobus placidus

Enzymatic Reactions Involving Ketyls: From a Chemical Curiosity to a General Biochemical Mechanism

Double‐Cubane [8Fe9S] Clusters: A Novel Nitrogenase‐Related Cofactor in Biology

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