Aldehyde oxidoreductase activity in Desulfovibrio gigas: In vitro reconstitution of an electron-transfer chain from aldehydes to the production of molecular hydrogen

Barata, Belarmino A.S.; LeGall, Jean; Moura, José J. G.

doi:10.1021/bi00094a012

Cited by 64 publications

(61 citation statements)

References 70 publications

(57 reference statements)

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“…These seemingly inconsistent results can be reconciled if the b2881 product oxidizes high intracellular levels of hypoxanthine and perhaps xanthine. This would not be surprising, since members of the xanthine oxidase family can have broad substrate specificies (3,11). In any case, our results do not conclusively define a function for this protein.…”

Section: Discussioncontrasting

confidence: 58%

Purine Catabolism in Escherichia coli and Function of Xanthine Dehydrogenase in Purine Salvage

2000

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Escherichia coli is not known to utilize purines, other than adenine and adenosine, as nitrogen sources. We reinvestigated purine catabolism because a computer analysis suggested several potential 54 -dependent promoters within a 23-gene cluster whose products have homology to purine catabolic enzymes. Our results did not provide conclusive evidence that the 54 -dependent promoters are active. Nonetheless, our results suggest that some of the genes are metabolically significant. We found that even though several purines did not support growth as the sole nitrogen source, they did stimulate growth with aspartate as the nitrogen source. Cells produced 14 CO 2 from minimal medium containing [ 14 C]adenine, which implies allantoin production. However, neither ammonia nor carbamoyl phosphate was produced, which implies that purine catabolism is incomplete and does not provide nitrogen during nitrogen-limited growth. We constructed strains with deletions of two genes whose products might catalyze the first reaction of purine catabolism. Deletion of one eliminated 14 CO 2 production from [ 14 C]adenine, which implies that its product is necessary for xanthine dehydrogenase activity. We changed the name of this gene to xdhA. The xdhA mutant grew faster with aspartate as a nitrogen source. The mutant also exhibited sensitivity to adenine, which guanosine partially reversed. Adenine sensitivity has been previously associated with defective purine salvage resulting from impaired synthesis of guanine nucleotides from adenine. We propose that xanthine dehydrogenase contributes to this purine interconversion.

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Section: Discussioncontrasting

confidence: 58%

Purine Catabolism in Escherichia coli and Function of Xanthine Dehydrogenase in Purine Salvage

2000

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“…gigas AOR was first described by Moura et al [68] and has been thought of as an aldehyde ''scavenger'', acting in a complex chain of electron-transfer proteins that links the oxidation of aldehydes to the reduction of protons [69]. The AOR-dependent nitrite reductase activity described herein could, therefore, constitute an alternative pathway to produce NO directly from aldehydes.…”

Section: Site Of Nitrite Reductionmentioning

confidence: 77%

Nitrite reduction by xanthine oxidase family enzymes: a new class of nitrite reductases

Maia

Moura

2010

J Biol Inorg Chem

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Mammalian xanthine oxidase (XO) and Desulfovibrio gigas aldehyde oxidoreductase (AOR) are members of the XO family of mononuclear molybdoenzymes that catalyse the oxidative hydroxylation of a wide range of aldehydes and heterocyclic compounds. Much less known is the XO ability to catalyse the nitrite reduction to nitric oxide radical (NO). To assess the competence of other XO family enzymes to catalyse the nitrite reduction and to shed some light onto the molecular mechanism of this reaction, we characterised the anaerobic XO-and AORcatalysed nitrite reduction. The identification of NO as the reaction product was done with a NO-selective electrode and by electron paramagnetic resonance (EPR) spectroscopy. The steady-state kinetic characterisation corroborated the XO-catalysed nitrite reduction and demonstrated, for the first time, that the prokaryotic AOR does catalyse the nitrite reduction to NO, in the presence of any electron donor to the enzyme, substrate (aldehyde) or not (dithionite). Nitrite binding and reduction was shown by EPR spectroscopy to occur on a reduced molybdenum centre. A molecular mechanism of AOR-and XO-catalysed nitrite reduction is discussed, in which the higher oxidation states of molybdenum seem to be involved in oxygen-atom insertion, whereas the lower oxidation states would favour oxygenatom abstraction. Our results define a new catalytic performance for AOR-the nitrite reduction-and propose a new class of molybdenum-containing nitrite reductases.

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“…However, its presence was suggested from spectroscopic studies (mainly electron paramagnetic resonance, EPR), which showed that most of the EPR properties of active DgAOR or AOR from Desulfovibrio desulfuricans ATCC 27774 (DdAOR) are similar to those of active XO [15,16]. In addition, cyanide acts as an inhibitor of DgAOR activity [17]; this is also the case in XO (where the cyanide is proposed to react with the sulfido ligand), and the desulfo form of DgAOR regains activity after resulfuration [18]. The position of the sulfido ligand in the active site has been debated; a crystal structure of ''resulfurated'' DgAOR crystals showed that the sulfido ligand introduced by adding an excess of sulfide ions was coordinated in the apical position to the molybdenum atom [19] (Fig.…”

Section: Introductionmentioning

confidence: 99%

Correlating EPR and X-ray structural analysis of arsenite-inhibited forms of aldehyde oxidoreductase

et al. 2006

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Two arsenite-inhibited forms of each of the aldehyde oxidoreductases from Desulfovibrio gigas and Desulfovibrio desulfuricans have been studied by X-ray crystallography and electron paramagnetic resonance (EPR) spectroscopy. The molybdenum site of these enzymes shows a distorted square-pyramidal geometry in which two ligands, a hydroxyl/water molecule (the catalytic labile site) and a sulfido ligand, have been shown to be essential for catalysis. Arsenite addition to active as-prepared enzyme or to a reduced desulfo form yields two different species called A and B, respectively, which show different Mo(V) EPR signals. Both EPR signals show strong hyperfine and quadrupolar couplings with an arsenic nucleus, which suggests that arsenic interacts with molybdenum through an equatorial ligand. X-ray data of single crystals prepared from EPR-active samples show in both inhibited forms that the arsenic atom interacts with the molybdenum ion through an oxygen atom at the catalytic labile site and that the sulfido ligand is no longer present. EPR and X-ray data indicate that the main difference between both species is an equatorial ligand to molybdenum which was determined to be an oxo ligand in species A and a hydroxyl/water ligand in species B. The conclusion that the sulfido ligand is not essential to determine the EPR properties in both MoAs complexes is achieved through EPR measurements on a substantial number of randomly oriented chemically reduced crystals immediately followed by X-ray studies on one of those crystals. EPR saturation studies show that the electron transfer pathway, which is essential for catalysis, is not modified upon inhibition.

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Aldehyde oxidoreductase activity in Desulfovibrio gigas: In vitro reconstitution of an electron-transfer chain from aldehydes to the production of molecular hydrogen

Cited by 64 publications

References 70 publications

Purine Catabolism in Escherichia coli and Function of Xanthine Dehydrogenase in Purine Salvage

Purine Catabolism in Escherichia coli and Function of Xanthine Dehydrogenase in Purine Salvage

Nitrite reduction by xanthine oxidase family enzymes: a new class of nitrite reductases

Correlating EPR and X-ray structural analysis of arsenite-inhibited forms of aldehyde oxidoreductase

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