1.17.4.1 ADP + thioredoxin the enzyme converts ribonucleotides to deoxyribonucleotides, a reaction that is essential for DNA biosynthesis and repair 1.17.4.1 CDP + thioredoxin - 1.17.4.1 CDP + thioredoxin the enzyme converts ribonucleotides to deoxyribonucleotides, a reaction that is essential for DNA biosynthesis and repair 1.17.4.1 GDP + thioredoxin - 1.17.4.1 additional information DNA damage checkpoints modulate RNR activity through the temporal and spatial regulation of its subunits 1.17.4.1 additional information each catalytic turnover by aerobic ribonucleotide reductase requires the assembly of the two proteins, R1 (alpha2) and R2 (beta2), to produce deoxyribonucleotides for DNA synthesis 1.17.4.1 additional information the Sml1-R1 interaction causes SML1-dependent lethality, the CX2C motif of Rnr1 Is essential for viability. overview 1.17.4.1 additional information human p53R2 is a 351-residue p53-inducible ribonucleotide reductase small subunit, hp53R2 supplies dNTPs for DNA repair to cells in G0-G1 in a p53-dependent fashion, rather than exhibiting cyclic dNTP synthesis. Hp53R2 structure-function relationship determination and analysis, overview 1.17.4.1 additional information ribonucleotide reductases catalyze the reduction of ribonucleotides to deoxyribonucleotides for DNA synthesis 1.17.4.1 additional information ribonucleotide reduction is the unique step in DNA-precursor biosynthesis and involves radical-dependent redox chemistry and diverse metallo-cofactors, overview. The Mn-RNR from the Gram-positive bacterium Corynebacterium ammoniagenes, strain ATCC 6872, belongs a distinct RNR class IV enzyme 1.17.4.1 additional information RNR is an essential enzyme that provides dNTPs for DNA replication and repair, regulation in response to genotoxic stress, overview 1.17.4.1 additional information catalysis by a class I RNR begins when a cysteine residue in the alpha2 subunit is oxidized to a thiyl radical by a cofactor about 35 A away in the beta2 subunit. In a class Ia or Ib RNR, a stable tyrosyl radical is the C oxidant, whereas a MnIV/FeIII cluster serves this function in the class Ic enzyme from Chlamydia trachomatis 1.17.4.1 additional information class Ia and Ib RNRs convert nucleoside diphosphates into 2'-deoxynucleoside diphosphates using glutaredoxin or thioredoxin as cofactor. Class II RNRs catalyze the same reaction but also convert nucleoside triphosphates to the correspondent 2'deoxy products, EC 1.17.4.2, overview 1.17.4.1 additional information class Ia RNRs convert nucleoside diphosphates into 2'-deoxynucleoside diphosphates using glutaredoxin or thioredoxin as cofactor 1.17.4.1 additional information the enzyme catalyzes the conversion of nucleoside 5'-diphosphates, NDPs, to deoxynucleotides, dNDPs. The active site for NDP reduction resides in the alpha2 subunit, and the essential diferric-tyrosyl radical, Y122 radical, cofactor that initiates transfer of the radical to the active site cysteine in R2 (C439), 35A ° removed, is located in subunit beta2. The oxidation involves a hopping mechanism through aromatic amino acids, Y122, W48, and Y356 in subunit beta2 to Y731, Y730, and C439 in subunit alpha2, and a reversible proton-coupled electron transfer 1.17.4.1 nucleoside 5'-diphosphate + glutaredoxin class I RNRs 1.17.4.1 nucleoside 5'-diphosphate + glutaredoxin class Ia RNRs 1.17.4.1 nucleoside 5'-diphosphate + NrdH-redoxin only class Ib RNRs 1.17.4.1 nucleoside 5'-diphosphate + thioredoxin class I and class II RNRs 1.17.4.1 nucleoside 5'-diphosphate + thioredoxin class Ia RNRs 1.17.4.1 ribonucleoside 5'-diphosphate + thioredoxin - 1.17.4.1 ribonucleoside 5'-diphosphate + thioredoxin the essential enzyme catalyzes the rate-limiting step in dNTP production for DNA synthesis 1.17.4.1 ribonucleoside diphosphate + reduced thioredoxin possible role in HSV-2-induced transformation 1.17.4.1 ribonucleoside diphosphate + reduced thioredoxin critical and rate-controlling step in pathway leading to DNA synthesis and cell replication 1.17.4.1 ribonucleoside diphosphate + reduced thioredoxin thioredoxin is the physiological reductant 1.17.4.1 ribonucleoside diphosphate + reduced thioredoxin enzyme catalyzes the first unique step in DNA synthesis 1.17.4.1 ribonucleoside diphosphate + thioredoxin - 1.17.4.1 ribonucleoside diphosphate + thioredoxin the enzyme catalyses the rate-limiting step of DNA synthesis in the pathogen 1.17.4.1 UDP + thioredoxin the enzyme converts ribonucleotides to deoxyribonucleotides, a reaction that is essential for DNA biosynthesis and repair