PMID:809436

Citation	Berglund, O (1975) Ribonucleoside diphosphate reductase induced by bacteriophage T4. III. Isolation and characterization of proteins B1 and B2. J. Biol. Chem. 250:7450-5
Abstract	Ribonucleoside diphosphate reductase determined by bacteriophage T4 consists of a tight complex (alpha2beta2) of the polypeptide chains alpha (Mr = 80,000 to 85,000) and beta (Mr = 35,000). The alpha2 dimer (= protein B1) was purified from Escherichia coli B infected with T4 mutant nrdB55 (Yeh, Y.C., and Tessman, I. (1972) Virology 47, 767-772) which carries an amber mutation in the gene coding for the beta polypeptide chain. Protein B1 contained binding sites for dATP, an allosteric effector of the reductase. The beta2 dimer (= protein B2) was purified by selective desorption with 1 M guanidine HCl from a dATP-Sepharose affinity column containing adsorbed native T4 ribonucleotide reductase. Protein B2, isolated this way, was enzymatically inactive due to partial loss of its iron but it could be reactivated by treatment with ferrous iron. Active protein B2 contained two atoms of non-heme iron per molecule and exhibited the optical and electron spin resonance spectra previously demonstrated in the native enzyme. The T4-induced proteins B1 and B2 were unable to reduce ribonucleotides when assayed separately but were active in combination. The proteins did not form catalytically functional hybrids with proteins B1 and B2 of Escherichia coli ribonucleotide reductase, neither did they cross-react immunologically with the latter. 5-Hydroxymethyl-dCTP, at concentrations above 10 muM, was a positive allosteric effector of T4 ribonucleotide reductase promoting the reduction of the pyrimidine ribonucleotides CDP and UDP. The nucleotide had little effect on E. coli ribonucleotide reductase.
Links	PubMed
Keywords	Coliphages/enzymology; DNA Viruses/enzymology; Drug Stability; Edetic Acid/pharmacology; Enzyme Induction; Escherichia coli/enzymology; Immunodiffusion; Iron/pharmacology; Magnesium/pharmacology; Molecular Weight; Ribonucleoside Diphosphate Reductase/biosynthesis; Ribonucleoside Diphosphate Reductase/immunology; Ribonucleoside Diphosphate Reductase/isolation & purification; Ribonucleotide Reductases/biosynthesis; Spectrophotometry
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BPT4:RIR1		GO:0005971: ribonucleoside-diphosphate reductase complex	ECO:0000314:		C		Figure 4 shows that NrdA and NrdB from bacteriophage T4 have no activity alone; both are necessary to form a complex capable of ribonucleoside-diphosphate reductase activity	complete CACAO 10851
BPT4:D9IER5	enables	GO:0032549: ribonucleoside binding	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
BPT4:D9IER5		GO:0032549: ribonucleoside binding	ECO:0000314:		F		Addition of 1M guanidine HCL cause dissociation of proteins B1 and B2. B2 protein recovered was enzymatically inactive until treatment with iron. Preparations of B2 containing 2.3g and 2.1g atoms of iron per mol and an excess of active B1 both showed ribonucleotide reductase activity yielded 315nM and 280nM of NADPH respectively. This can be observed in Fig4. The molecular activity of native reductase is between 200nm and 300nm. Also, solutions containing inactive B2 without iron had 2% the activity of iron treated B2.	complete CACAO 10896

References

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