Flavo Rubredoxins

3 (Flavo)Rubredoxins. - Rubredoxins are small, Mr 6 kDa, mononuclear iron-sulfur proteins, whose role remains largely elusive, except in a few cases such as in the Pseudomonas-ty Q alkane hydroxylation system and in an oxygenutilizing pathway in the formally anaerobic sulfate reducer Desulfovibrio gigas. These organisms exploit the ability of flavoproteins to act as in vivo redox 

The recombinant flavorubredoxin from Escherichia coli is an example of a two-component flavoprotein. It consists of a unique arrangement of structural modules in which a large, partly flavodoxin-like domain containing a single FMN is attached to a rubredoxin-like one. In order to assess the role of the rubredoxin domain, Gomes and co-workers have also characterized flavorubredoxin and a truncated form lacking the rubredoxin domain by EPR and optical spectroscopy. Electron donation was found to proceed through the rubredoxin domain of the flavorubredoxin as the rubredoxin truncated protein does not react with flavorubredoxin reductase (the terminal component of the pathway). Thus, it could be concluded that flavorubredoxin is a fusion of a flavoprotein with its redox partner. 

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ACP = acyl carrier protein ACPA D = ACPA desat-urase AlkB = octane 1-monooxygenase AOX = alternative oxidase DMQ hydroxylase = 5-demethoxyquinone hydroxylase EXAFS = extended X-ray absorption fine structure spectroscopy FMN = flavin mononucleotide FprA = flavoprotein A (flavo-diiron enzyme homologue) Hr = hemerythrin MCD = magnetic circular dichroism MME hydroxylase = Mg-protophorphyrin IX monomethyl ester hydroxylase MMO = methane monooxygenase MMOH = hydroxylase component of MMO NADH = reduced nicotinamide adenine dinucleotide PAPs = purple acid phosphatases PCET = proton-coupled electron transfer, PTOX = plastid terminal oxidase R2 = ribonucleotide reductase R2 subunit Rbr = rubrerythrin RFQ = rapid freeze-quench RNR = ribonucleotide reductase ROO = rubredoxin oxygen oxidoreductase XylM = xylene monooxygenase. 

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