Publications

• Flavorubredoxin, an inducible catalyst for nitric oxide reduction and detoxification in Escherichia coli.

  Gardner A.M., Helmick R.A., Gardner P.R.

  Nitric oxide (NO) is a poison, and organisms employ diverse systems to protect against its harmful effects. In Escherichia coli, ygaA encodes a transcription regulator (b2709) controlling anaerobic NO reduction and detoxification. Adjacent to ygaA and oppositely transcribed are ygaK (encoding a fl ... >> More

  Nitric oxide (NO) is a poison, and organisms employ diverse systems to protect against its harmful effects. In Escherichia coli, ygaA encodes a transcription regulator (b2709) controlling anaerobic NO reduction and detoxification. Adjacent to ygaA and oppositely transcribed are ygaK (encoding a flavorubredoxin (flavoRb) (b2710) with a NO-binding non-heme diiron center) and ygbD (encoding a NADH:(flavo)Rb oxidoreductase (b2711)), which function in NO reduction and detoxification. Mutation of either ygaA or ygaK eliminated inducible anaerobic NO metabolism, whereas ygbD disruption partly impaired the activity. NO-sensitive [4Fe-4S] (de)hydratases, including the Krebs cycle aconitase and the Entner-Doudoroff pathway 6-phosphogluconate dehydratase, were more susceptible to inactivation in ygaK or ygaA mutants than in the parental strain, and these metabolic poisonings were associated with conditional growth inhibitions. flavoRb (NO reductase) and flavohemoglobin (NO dioxygenase) maximally metabolized and detoxified NO in anaerobic and aerobic E. coli, respectively, whereas both enzymes scavenged NO under microaerobic conditions. We suggest designation of the ygaA-ygaK-ygbD gene cluster as the norRVW modulon for NO reduction and detoxification. << Less

  J. Biol. Chem. 277:8172-8177(2002) [PubMed] [EuropePMC]

• A novel type of nitric-oxide reductase. Escherichia coli flavorubredoxin.

  Gomes C.M., Giuffre A., Forte E., Vicente J.B., Saraiva L.M., Brunori M., Teixeira M.

  Escherichia coli flavorubredoxin is a member of the family of the A-type flavoproteins, which are built by two core domains: a metallo-beta-lactamase-like domain, at the N-terminal region, harboring a non-heme di-iron site, and a flavodoxin-like domain, containing one FMN moiety. The enzyme from E ... >> More

  Escherichia coli flavorubredoxin is a member of the family of the A-type flavoproteins, which are built by two core domains: a metallo-beta-lactamase-like domain, at the N-terminal region, harboring a non-heme di-iron site, and a flavodoxin-like domain, containing one FMN moiety. The enzyme from E. coli has an extra module at the C terminus, containing a rubredoxin-like center. The A-type flavoproteins are widespread among strict and facultative anaerobes, as deduced from the analysis of the complete prokaryotic genomes. In this report we showed that the recombinant enzyme purified from E. coli has nitric-oxide reductase activity with a turnover number of approximately 15 mol of NO.mol enzyme(-1).s(-1), which was well within the range of those determined for the canonical heme b(3)-Fe(B) containing nitric-oxide reductases (e.g. approximately 10-50 mol NO.mol enzyme(-1).s(-1) for the Paracoccus denitrificans NOR). Furthermore, it was shown that the activity was due to the A-type flavoprotein core, as the rubredoxin domain alone exhibited no activity. Thus, a novel family of prokaryotic NO reductases, with a non-heme di-iron site as the catalytic center, was established. << Less

  J. Biol. Chem. 277:25273-25276(2002) [PubMed] [EuropePMC]

• The NorR protein of Escherichia coli activates expression of the flavorubredoxin gene norV in response to reactive nitrogen species.

  Hutchings M.I., Mandhana N., Spiro S.

  The Escherichia coli norVW genes encode a flavorubredoxin and NADH:(flavo)rubredoxin reductase, respectively, which are involved in nitric oxide detoxification under anaerobic growth conditions. Here it is shown that the norVW genes also have a role in protection against reactive nitrogen intermed ... >> More

  The Escherichia coli norVW genes encode a flavorubredoxin and NADH:(flavo)rubredoxin reductase, respectively, which are involved in nitric oxide detoxification under anaerobic growth conditions. Here it is shown that the norVW genes also have a role in protection against reactive nitrogen intermediates generated from nitroprusside. Transcription from the norV promoter is activated by the presence of nitroprusside in the growth medium; activation requires the product of a divergently transcribed regulatory gene, norR. << Less

  J. Bacteriol. 184:4640-4643(2002) [PubMed] [EuropePMC]