Rubredoxin oxidoreductase

Chen L, Liu M-Y, LeGall J, et al. 1993b. Purification and characterization of an NADH-rubredoxin oxidoreductase involved in the utilization of oxygen by Desulfovibrio gigas. J Biochem 216 443-8. 

Lumppio HL, Shenvi NV, Summers AO, et al. 2001. Rubrerythrin and rubredoxin oxidoreductase in Desulfovibrio vulgaris. A novel oxidative stress protection system. J Bacteriol 183 101-8. 

Das A, Coulter ED, Kurtz DM, Jr, Ljungdahl LG. 2001. Five-gene cluster in Clostridium thermo aceticum consisting of two divergent operons encoding rubredoxin oxidoreductase— rubredoxin and rubrerythrin— type A flavoprotein— high-molecular-weight rubredoxin. J Bacteriol 183 1560-7. 

Table 14.2. Proposed functions of rubrerythrin, rubredoxin oxidoreductase, rubredoxin, high molecular weight rubredoxin, and type A flavoprotein in different bacteria.

The concentrated sample from the previous colunnn is loaded onto a colunm (5 X 12 cm) of Blue Sepharose (Pharmacia Biotech) equilibrated with buffer C. The column is eluted with a 1.4 liter linear gradient of 0 to 2 Af NaCl in buffer C and 50-ml fractions are collected. FNOR activity starts to elute as 1.5 A/ NaCl is applied. It should be noted that three peaks of the NBVOR assay are separated by this chromatography step. The first peak to elute contains 20% of the total activity and the enzyme responsible has not been characterized. The third peak to elute represents 40% or the NBVOR activity and in this case BV reduction is catalyzed by NADPH rubredoxin oxidoreductase (NROR). It is the second peak of NBVOR activity, which also contains about 40% of the total, that corresponds to FNOR, and this starts to elute as 1.7 Af NaCl is applied to the colunm. Fractions containing FNOR are combined (600 ml) and concentrated to 30 ml by ultrafiltration (PM30 membrane). 

NAD(P)H rubredoxin oxidoreductase (NROR) catalyzes the reduction of the redox protein rubredoxin with NAD(P)H as the electron donor. Rubredoxin is a small protein ( 5 kDa) that contains a single Fe atom coordinated by the sulfur... 

Complex heme proteins which contain redox centers other than just electron transfer hemes are normally associated with enzymatic catalysis. In this section, we will refer to some of the best studied complex heme proteins sulfite reductase, nitrite reductase, formate dehydrogenase, fumarate reductase and rubredoxin-oxygen oxidoreductase. 

A new member of the family of nonheme diiron enzymes recently discovered is called rubrerythrin. This metalloprotein is formally classified as an oxidoreductase (rubredoxin oxygen oxidoreductase). The diiron(III,III) active site structure is displayed in Figure 2(f). This biomolecule possesses two histidines coordinated to one iron and one histidine coordinated to the second iron. A carboxylate bridges the two irons and there are carboxylate ligands also coordinated to each iron. The purpose of this enzyme in the strict anaerobe is to safely reduce oxygen to water. 

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. 

Another novel candidate with NO reductase activity is a flavodiiron protein from Moorella thermoacetica [114]. Two genes of this strictly anaerobic, aceto-genic bacterium, namely and hrb, have no known function. FprA contains flavin mononucleotide (FMN) and a non-heme diiron site while Hrb contains FMN and a rubredoxin-like [Fe(SCys)4] site. The combination of Hrb and FprA exhibits NADH NO oxidoreductase activity. 

RUBREDOXIN-OXYGEN OXIDOREDUCTASE AND NITRIC OXIDE REDUCTASES... 

---