Intermolecular electron transfer in two-iron superoxide reductase: a putative role for the desulforedoxin center as an electron donor to the iron active site |
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Authors: | Florence Bonnot Simon Duval Murielle Lombard Julien Valton Chantal Houée-Levin Vincent Nivière |
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Affiliation: | 1.Laboratoire de Chimie et Biologie des Métaux,iRTSV-CEA Grenoble/CNRS/Université Joseph Fourier,Grenoble Cedex 9,France;2.Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques,UMR 8601, Université René Descartes Paris 5,Paris Cedex 06,France;3.Laboratoire de Chimie Physique, Centre Universitaire,UMR 8000 CNRS/Université Paris-Sud and CNRS,Orsay Cedex,France;4.Cellectis Bioresearch,Romainville,France |
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Abstract: | Superoxide reductase (SOR) is a superoxide detoxification system present in some microorganisms. Its active site consists of an unusual mononuclear iron center with an FeN4S1 coordination which catalyzes the one-electron reduction of superoxide to form hydrogen peroxide. Different classes of SORs have been described depending on the presence of an additional rubredoxin-like, desulforedoxin iron center, whose function has remained unknown until now. In this work, we investigated the mechanism of the reduction of the SOR iron active site using the NADPH:flavodoxin oxidoreductase from Escherichia coli, which was previously shown to efficiently transfer electrons to the Desulfoarculus baarsii SOR. When present, the additional rubredoxin-like iron center could function as an electronic relay between cellular reductases and the iron active site for superoxide reduction. This electron transfer was mainly intermolecular, between the rubredoxin-like iron center of one SOR and the iron active site of another SOR. These data provide the first experimental evidence for a possible role of the rubredoxin-like iron center in the superoxide detoxifying activity of SOR. |
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