Redox and spectroscopic properties of the Escherichia coli nitric oxide-detoxifying system involving flavorubredoxin and its NADH-oxidizing redox partner.
Under anaerobic conditions, the flavodiiron NO-reductase from Escherichia coli (flavorubredoxin, FlRd) constitutes one of the major protective enzymes against nitric oxide. The redox and spectroscopic properties of the rubredoxin (Rd), non-heme diiron, and FMN sites of flavorubredoxin were determined, which was complemented by the study of truncated versions of FlRd: one consisting only of its rubredoxin module, and another consisting of its flavodiiron structural core (lacking the Rd domain). The studies here reported were performed by a combination of potentiometry with visible and EPR spectroscopies. Moreover, we present the first direct EPR evidence for the presence of the non-heme diiron site in the flavodiiron proteins family. Also, the redox properties of the FlRd physiological partner, the NADH:flavorubredoxin oxidoreductase (FlRd-Red), were determined. It is further shown that the redox properties of this complex electron transfer system are fine-tuned upon interaction of the two enzymes.
Vicente
João B
JB
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, Apt. 127, 2781-901 Oeiras, Portugal.
Teixeira
Miguel
M
D004574:Electromagnetic Fields; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry; D006418:Heme / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D008954:Models, Biological; D008956:Models, Chemical; D009243:NAD / Q000737:chemistry*; D009569:Nitric Oxide / Q000378:metabolism*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D012416:Rubredoxins / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods; D014466:Ultraviolet Rays
D029968:Escherichia coli Proteins; D012416:Rubredoxins; D009243:NAD; D009569:Nitric Oxide; D006418:Heme; D007501:Iron; D010088:Oxidoreductases; D010100:Oxygen