Flavodoxin hydroquinone provides electrons for the ATP-dependent reactivation of protein-bound corrinoid cofactors.
FEBS J
; 287(22): 4971-4981, 2020 11.
Article
em En
| MEDLINE
| ID: mdl-32160390
ABSTRACT
Corrinoid-dependent enzyme systems rely on the super-reduced state of the protein-bound corrinoid cofactor to be functional, for example, in methyl transfer reactions. Due to the low redox potential of the [CoII ]/[CoI ] couple, autoxidation of the corrinoid cofactor occurs and leads to the formation of the inactive [CoII ]-state. For the reactivation, which is an energy-demanding process, electrons have to be transferred from a physiological donor to the corrinoid cofactor by the help of a reductive activator protein. In this study, we identified reduced flavodoxin as electron donor for the ATP-dependent reduction of protein-bound corrinoid cofactors of bacterial O-demethylase enzyme systems. Reduced flavodoxin was generated enzymatically using pyruvateferredoxin/flavodoxin oxidoreductase rather than hydrogenase. Two of the four flavodoxins identified in Acetobacterium dehalogenans and Desulfitobacterium hafniense DCB-2 were functional in supplying electrons for corrinoid reduction. They exhibited a midpoint potential of about -400 mV (ESHE , pH 7.5) for the semiquinone/hydroquinone transition. Reduced flavodoxin could be replaced by reduced clostridial ferredoxin. It was shown that the low-potential electrons of reduced flavodoxin are first transferred to the iron-sulfur cluster of the reductive activator and finally to the protein-bound corrinoid cofactor. This study further highlights the importance of reduced flavodoxin, which allows maintaining a variety of enzymatic reaction cycles by delivering low-potential electrons.
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MEDLINE
Assunto principal:
Oxirredutases
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Proteínas de Bactérias
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Trifosfato de Adenosina
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Corrinoides
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Elétrons
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Flavodoxina
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Hidroquinonas
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article