PMID:21068394

Citation	García, LL, Rivas-Marín, E, Floriano, B, Bernhardt, R, Ewen, KM, Reyes-Ramírez, F and Santero, E (2011) ThnY is a ferredoxin reductase-like iron-sulfur flavoprotein that has evolved to function as a regulator of tetralin biodegradation gene expression. J. Biol. Chem. 286:1709-18
Abstract	Previous genetic studies in Sphingomonas macrogolitabida strain TFA have established that expression of genes involved in tetralin biodegradation (thn genes) requires the function of the LysR type activator ThnR and also ThnY. Sequence comparison indicated that ThnY is homologous to bacterial oxygenase-coupled NAD(P)H-dependent ferredoxin reductases. However, ThnY showed substitutions in highly conserved positions of the pyridine nucleotide binding domain of these ferredoxin reductases. ThnY expression is co-regulated with all other genes required for tetralin biodegradation, and presumably thnY is part of the thnCA3A4RY operon. ThnY has been purified, and its biochemical and functional properties were characterized. ThnY was found to be a monomeric orange-brown iron-sulfur flavoprotein (estimated mass of 37,000 Da) containing one non-covalently attached flavin adenine dinucleotide and one plant type ferredoxin 2Fe-2S cluster. It can be efficiently reduced by dithionite, but reduction by pyridine nucleotides was very poor. Consistently, ThnY-dependent reduction of cytochrome c, ferricyanide, or 2,6-dichlorophenolindophenol using NAD(P)H as the electron donor was undetectable or very weak. The addition of ThnY to electrophoretic mobility shift assays containing ThnR and a probe bearing two thn divergent promoters resulted in a 3-fold increase in protein-DNA complex formation affinity, which indicates that ThnY directly promotes thn transcription activation by ThnR.
Links	PubMed PMC3023465 Online version:10.1074/jbc.M110.184648
Keywords	Bacterial Proteins/biosynthesis; Bacterial Proteins/genetics; Biodegradation, Environmental/drug effects; Cytochromes c/genetics; Cytochromes c/metabolism; Escherichia coli/enzymology; Escherichia coli/genetics; Evolution, Molecular; Ferredoxin-NADP Reductase/biosynthesis; Ferredoxin-NADP Reductase/genetics; Ferricyanides/metabolism; Flavoproteins/biosynthesis; Flavoproteins/genetics; Gene Expression Regulation, Bacterial/drug effects; Gene Expression Regulation, Bacterial/physiology; Gene Expression Regulation, Enzymologic/drug effects; Gene Expression Regulation, Enzymologic/physiology; Operon/physiology; Oxidation-Reduction/drug effects; Promoter Regions, Genetic/physiology; Protein Structure, Tertiary; Sphingomonas/enzymology; Sphingomonas/genetics; Tetrahydronaphthalenes/metabolism; Tetrahydronaphthalenes/pharmacology; Transcription Factors/genetics; Transcription Factors/metabolism; Transcription, Genetic/drug effects; Transcription, Genetic/physiology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
9SPHN:Q687Z8		GO:0052738: oxidoreductase activity, acting on the aldehyde or oxo group of donors, with a quinone or similar compound as acceptor	ECO:0000269:		F		Fig 6 demonstrates time course for anaerobic reduction of ThnY with NADPH	complete

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