Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have cloned and sequenced cDNAs coding for the R1 and R2 proteins of ribonucleotide reductase from zebrafish (Danio rerio). This ribonucleotide reductase shows high amino acid sequence identity to those of other vertebrates. The R1 cDNA has a coding sequence of 2382 bp, yielding a 794 amino acid protein, and the R2 cDNA has a coding sequence of 1158 bp, yielding a 386 amino acid protein. The zebrafish R1 shows 94% similarity and R2 shows 91% similarity to the human R1 and R2, respectively. The similarity extends to intron positions, of which the equivalent of mouse R2 intron 3 has been studied.
Mol Mar Biol Biotechnol 1996 Dec
PMID:Cloning and sequencing of cDNAs encoding ribonucleotide reductase from zebrafish Danio rerio. 898 96

The synthesis of DNA in CCl 39 cells is inhibited by the presence of the Fe2+ chelator bathophenanthroline disulfonate (BPS) when growth is stimulated by thrombin EGF plus insulin, but not by fetal calf serum. The presence of transferrin and Fe3+ in fetal calf serum can be the basis for lack of BPS effect with serum. The impermeable Fe3+ chelator Tiron does not, by itself, inhibit growth factor induced DNA synthesis, but it induces together with BPS inhibition on fetal calf serum induced DNA synthesis. The combined effect of BPS and Tiron is similar to inhibition of DNA synthesis by impermeable polyvalent DTPA which can chelate both Fe2+ and Fe3+ but does not inhibit ribonucleotide reductase in intact cells. Ferrous iron that bind BPS can relieve the inhibition at stoichiometric concentration. Ferric iron also prevents the inhibition even though it does not bind BPS. BPS does not inhibit DNA synthesis in HeLa cells. BPS reacts with iron from CCl 39 cells but not from HeLa cells. Data show that iron available for impermeable external chelators is in the ferrous state, and that exogenous iron should be reduced before it reverses the inhibition.
Biochem Mol Biol Int 1997 Feb
PMID:Inhibition of DNA synthesis in CCL 39 cells by impermeable iron chelators. 906 70

Flavodoxin reductase from Escherichia coli is an FAD-containing oxidoreductase that transports electrons between flavodoxin or ferredoxin and NADPH. Together with flavodoxin, the enzyme is involved in the reductive activation of three E. coli enzymes: cobalamin-dependent methionine synthase, pyruvate formate lyase and anaerobic ribonucleotide reductase. An additional function for the oxidoreductase appears to be to protect the bacteria against oxygen radicals. The three-dimensional structure of flavodoxin reductase has been solved by multiple isomorphous replacement, and has been refined at 1.7 A to an R-value of 18.4% and Rfree 24.8%. The monomeric molecule contains one beta-sandwich FAD domain and an alpha/beta NADP domain. The overall structure is similar to other reductases of the NADP-ferredoxin reductase family in spite of the low sequence similarities within the family. Flavodoxin reductase lacks the loop which is involved in the binding of the adenosine moiety of FAD in other FAD binding enzymes of the superfamily but is missing in the FMN binding phthalate dioxygenase reductase. Instead of this loop, the adenine interacts with an extra tryptophan at the C terminus. The FAD in flavodoxin reductase has an unusual bent conformation with a hydrogen bond between the adenine and the isoalloxazine. This is probably the cause of the unusual spectrum of the enzyme. There is a pronounced cleft close to the isoalloxazine that appears to be well suited for binding of flavodoxin/ferredoxin. Two extra short strands of the NADP-binding domain probably act as an anchor point for the binding of flavodoxin.
J Mol Biol 1997 Apr 25
PMID:The three-dimensional structure of flavodoxin reductase from Escherichia coli at 1.7 A resolution. 914 48

Ribonucleotide reductases catalyze the formation of deoxyribonucleotides by the reduction of the corresponding ribonucleotides. Eukaryotic ribonucleotide reductases are alpha2beta2 tetramers; each of the larger, alpha subunits possesses binding sites for substrate and allosteric effectors, and each of the smaller, beta subunits contains a binuclear iron complex. The iron complex interacts with a specific tyrosine residue to form a tyrosyl free radical which is essential for activity. Previous work has identified two genes in the yeast Saccharomyces cerevisiae, RNR1 and RNR3, that encode alpha subunits and one gene, RNR2, that encodes a beta subunit. Here we report the identification of a second gene from this yeast, RNR4, that encodes a protein with significant similarity to the beta-subunit proteins. The phenotype of rnr4 mutants is consistent with that expected for a defect in ribonucleotide reductase; rnr4 mutants are supersensitive to the ribonucleotide reductase inhibitor hydroxyurea and display an S-phase arrest at their restrictive temperature. rnr4 mutant extracts are deficient in ribonucleotide reductase activity, and this deficiency can be remedied by the addition of exogenous Rnr4p. As is the case for the other RNR genes, RNR4 is induced by agents that damage DNA. However, Rnr4p lacks a number of sequence elements thought to be essential for iron binding, and mutation of the critical tyrosine residue does not affect Rnr4p function. These results suggest that Rnr4p is catalytically inactive but, nonetheless, does play a role in the ribonucleotide reductase complex.
Mol Cell Biol 1997 Oct
PMID:Rnr4p, a novel ribonucleotide reductase small-subunit protein. 931 71

The metabolism of nitrovasodilators such as glyceryl trinitrate and nitroprusside provides the active moiety of these drugs (that is, nitric oxide). This process is not limited to the known nitrovasodilators, but also occurs with nitroaromatic antimicrobials. Here we report that the administration of hydroxyurea, an antitumor drug, to rats at pharmacological doses formed detectable nitrosyl hemoglobin, which increased with dose. At higher doses, nitrosyl hemoprotein complexes could also be detected in liver tissue. [15N]hydroxyurea was synthesized and compared with [14N]hydroxyurea. These observations verified that nitric oxide detected as nitrosyl hemoglobin or nitrosyl hemoprotein complexes in rats was the result of the metabolism of hydroxyurea. The time course and dose-dependence of nitric oxide generation were also investigated. Hydroxyurea's antineoplastic activity is caused by its direct action on ribonucleotide reductase, the rate-limiting enzyme in DNA synthesis. Because nitric oxide also inhibits ribonucleotide reductase, this metabolite may supplement this action of hydroxyurea. In addition, the known ability of hydroxyurea to ease the pain of sickle cell anemia patients may be the result of vasodilation by the drug-derived nitric oxide.
Mol Pharmacol 1997 Dec
PMID:In vivo production of nitric oxide in rats after administration of hydroxyurea. 941 18

The classic function for thioredoxin is to act as a hydrogen donor for the enzyme ribonucleotide reductase, which is essential for DNA synthesis. In addition, thioredoxin participates in the regulation of different metabolic processes via thiol redox control. These kind of processes involve changes in the activity of different enzymes, receptors or transcription factors via dithiol/disulphide interchange reactions. Thioredoxin is present in the human decidua and trophoblasts. This study was performed to investigate whether thioredoxin mRNA is present in the human cervix, and differently expressed during pregnancy as compared with the non-pregnant state. Cervical biopsies and serum samples were obtained from 28 late pregnant, 41 post-partum and 15 non-pregnant menstruating women. The tissues were analysed for thioredoxin mRNA content using a solution hybridization technique. The thioredoxin mRNA level increased 3-fold at late pregnancy in comparison with the non-pregnant state. No further increase was seen immediately after parturition, either after spontaneous delivery or after pharmacological induction. There was a positive correlation between the cervical thioredoxin mRNA level and the serum oestradiol concentration in the non-pregnant group. We suggest that thioredoxin mRNA in the human cervix is regulated, at least partly, by oestradiol.
Mol Hum Reprod 1997 Dec
PMID:The expression of thioredoxin mRNA is increased in the human cervix during pregnancy. 946 57

The determination of the nuclear magnetic resonance (NMR) solution structure of fully reduced human glutaredoxin is described. A total of 1159 useful nuclear Overhauser effect (NOE) upper distance constraints and 187 dihedral angle constraints were obtained as the input for the structure calculations for which the torsion angle dynamics program DYANA has been utilized followed by energy minimization in water with the AMBER force field as implemented in the program OPAL. The resulting 20 conformers have an average root-mean-square deviation value relative to the mean coordinates of 0.54 A for all the backbone atoms N, Calpha and C', and of 1.01 A for all heavy atoms. Human glutaredoxin consists of a four-stranded mixed beta-sheet composed of residues 15 to 19, 43 to 47, 72 to 75 and 78 to 81, and five alpha-helices composed of residues 4 to 9, 24 to 34, 54 to 65, 83 to 91, and 94 to 100. Comparisons with the structures of Escherichia coli glutaredoxin-1, pig liver glutaredoxin and human thioredoxin were made. Electrostatic calculations on the human glutaredoxin structure and that of related proteins provide an understanding of the variation of pKa values for the nucleophilic cysteine in the active site observed among these proteins. In addition, the high-resolution NMR solution structure of human glutaredoxin has been used to model the binding site for glutathione and for ribonucleotide reductase B1 by molecular dynamics simulations.
J Mol Biol 1998 Jul 24
PMID:The NMR solution structure of human glutaredoxin in the fully reduced form. 967 97

Two catalytic functions were required, minimally, for the appearance of DNA in evolution: a ribonucleotide reductase (RNR) and a reverse transcriptase (RT). If one accepts the explanatory strength of the RNA world model, it is clear that DNA molecules arose in the RNA world at some stage during the early evolution of cells. I suggest that competition for limited and valuable resources such as nucleotides, amino acids, and sugars made an early appearance among RNA cells, RNA viruses, viroids, and RNA plasmids. Structural and functional similarities between the different types of polymerases favor the simple hypothesis that the first RTs were RNA polymerase mutants that preferentially joined together preexisting deoxyribonucleotide triphosphates (dNTPs) using RNA templates. What was the role of dNTPs inside cells before DNA was synthesized and tested by natural selection? The oxygen atom that is removed by the reductase is of crucial importance to many ribozyme functions, since the 2'-OH is a strong nucleophile that forms transitional states during catalysis. Consequently, a RNR may have been used by cellular parasites to inhibit ribozyme action. Thus, DNA may have been, initially, an inert by-product of retrotranscription in lineages that acquired RTs and could synthesize DNA molecules using cellular RNA templates to detoxify the intracellular environment. DNA was useless as template until a transcriptase (DNA-dependent RNA polymerase) evolved that could copy (-)DNA to reconstitute the (+)RNA genome, indeed a successful way of confronting ribonuclease threats in the RNA world.
J Mol Evol 1998 Aug
PMID:Inhibition of ribozymes by deoxyribonucleotides and the origin of DNA. 969 60

In Saccharomyces cerevisiae, MEC1 and RAD53 are essential for cell growth and checkpoint function. Their essential role in growth can be bypassed by deletion of a novel gene, SML1, which functions after several genes whose overexpression also suppresses mec1 inviability. In addition, sml1 affects various cellular processes analogous to overproducing the large subunit of ribonucleotide reductase, RNR1. These include effects on mitochondrial biogenesis, on the DNA damage response, and on cell growth. Consistent with these observations, the levels of dNTP pools in sml1 delta strains are increased compared to wild-type. This effect is not due to an increase in RNR transcription. Finally, both in vivo and in vitro experiments show that Sml1 binds to Rnr1. We propose that Sml1 inhibits dNTP synthesis posttranslationally by binding directly to Rnr1 and that Mec1 and Rad53 are required to relieve this inhibition.
Mol Cell 1998 Sep
PMID:A suppressor of two essential checkpoint genes identifies a novel protein that negatively affects dNTP pools. 977 71

Eukaryotic ribonucleotide reductase (RNR), the enzyme involved in the synthesis of the deoxyribonucleotides, consists of two R1 and R2 subunits whose activities and gene expression are differentially regulated during the cell cycle and are preferentially induced at the G1/S transition. We have isolated three cDNA clones from a tobacco S phase library, two encoding the large R1 subunit, the first cloned in plants, and one encoding the small R2 subunit. From Southern blot hybridization we deduce that RNR2 is encoded by a single-copy gene whereas RNR1 is encoded by a small multigene family. The level of RNR mRNA is cell-cycle regulated showing a maximum in S phase. In mid-S phase, RNR2 transcripts show a higher maximum level than RNR1 transcripts. Analysis of the effects of various cell cycle inhibitors added to freshly subcultured stationary phase cells leads to the conclusion that RNR gene induction at the entry of the cells into the cell cycle takes place in late G1-early S phase. Addition of DNA synthesis-blocking agents to cycling cells synchronized in mid-S phase resulted in an enhancement of RNR transcript level, thus suggesting that RNR gene expression may be linked to the DNA synthesis rate by a feedback-like regulatory mechanism.
Plant Mol Biol 1998 Nov
PMID:Molecular characterization of tobacco ribonucleotide reductase RNR1 and RNR2 cDNAs and cell cycle-regulated expression in synchronized plant cells. 986 97


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