Sterile alpha motif and HD-domain containing protein 1 (SAMHD1) is a triphosphohydrolase converting deoxynucleoside triphosphates (dNTPs) to deoxynucleosides. The enzyme was recently identified as component of the human innate immune system that restricts HIV-1 infection by removing dNTPs required for viral DNA synthesis. SAMHD1 has deep evolutionary roots ubiquitous in organs. Here we identify general function regulation dNTP pools cultured cells. nuclear variably expressed during cell...

The abbreviation used is: dNTPs, deoxynucleoside triphosphates.the dTTP pool increased in these and most other cell lines.We found recently that hydroxyurea 3T6 cells stimulated the uptake of pyrimidine deoxyribonucleosides from medium (16).Conditioned contains relatively large amounts deoxyuridine ( 17) phosphorylation this nucleoside contributed to rise pool.In same dCTP was rapidly halved after addition then remained at a plateau value 16).Phosphorylation deoxycytidine might have...

Nucleoside monophosphate phosphohydrolases or 5′-nucleotidases (members of EC 3.1.3.5 and 3.1.3.6) dephosphorylate non-cyclic nucleoside monophosphates to nucleosides inorganic phosphate. Seven human with different subcellular localization have been cloned (Table I). Sequence comparisons show high homology only between cytosolic 5′-nucleotidase IA (cN-IA) 1The abbreviations used are: cNcytosolic 5′-nucleotidasecdNcytosolic 5′(3′)-deoxynucleotidaseeNecto-5′-nucleotidasemdNmitochondrial...

Eukaryotic cells contain a delicate balance of minute amounts the four deoxyribonucleoside triphosphates (dNTPs), sufficient only for few minutes DNA replication. Both deficiency and surplus single dNTP may result in increased mutation rates, faulty repair or mitochondrial depletion. dNTPs are usually quantified by an enzymatic assay which incorporation radioactive dATP (or dTTP dATP) into specific synthetic oligonucleotides polymerase is proportional to concentration unknown dNTP. We find...

Ribonucleotide reductase provides deoxynucleotides for nuclear and mitochondrial (mt) DNA replication repair. The mammalian enzyme consists of a catalytic (R1) radical-generating (R2 or p53R2) subunit. During S-phase, R1/R2 complex is the major provider deoxynucleotides. p53R2 induced by p53 after damage was proposed to supply repair translocating from cytosol cell nucleus. Similarly R1 R2 were claimed move nucleus during S-phase provide replication. These models suggest translocation...

In postmitotic mammalian cells, protein p53R2 substitutes for R2 as a subunit of ribonucleotide reductase. human patients with mutations in RRM2B , the gene p53R2, mitochondrial (mt) DNA synthesis is defective, and skeletal muscle presents severe mtDNA depletion. Skin fibroblasts isolated from patient lethal homozygous missense mutation grow normally culture an unchanged complement mtDNA. During active growth, four dNTP pools do not differ size normal controls, whereas during quiescence,...

A specific ribonucleoside triphosphate reductase is induced in anaerobic Escherichia coli. This enzyme, as isolated, lacks activity the test tube and can be activated anaerobically with S-adenosylmethionine, NADPH, two previously uncharacterized E. coli fractions. The gene for one of these, named dA1, was cloned sequenced. We found an open reading frame coding a polypeptide 248 amino acid residues, molecular weight 27,645 N-terminal segment identical to that determined by direct Edman...

Nuclear and mitochondrial (mt) DNA replication occur within two physically separated compartments on different time scales. Both require a balanced supply of dNTPs. During S phase, dNTPs for nuclear are synthesized de novo from ribonucleotides by salvage thymidine in the cytosol. Mitochondria contain specific kinases deoxyribonucleosides that may provide compartmentalized synthesis Here we investigate source intra-mt phosphates their relationship to cytosolic pools isotope-flow experiments...

Human fibroblasts in culture obtain deoxynucleotides by de novo ribonucleotide reduction or salvage of deoxynucleosides. In cycling cells the pathway dominates, but quiescent becomes important. Two forms active mammalian reductases are known. Each form contains catalytic R1 protein, two differ with respect to second protein (R2 p53R2). R2 is cell cycle-regulated, degraded during mitosis, and absent from cells. The recently discovered p53-inducible p53R2 was proposed be linked DNA repair...

Three cytosolic and one plasma membrane-bound 5′-nucleotidases have been cloned characterized. Their various substrate specificities suggest widely different functions in nucleotide metabolism. We now describe a 5′-nucleotidase mitochondria. The enzyme, named dNT-2, dephosphorylates specifically the 5′- 2′(3′)-phosphates of uracil thymine deoxyribonucleotides. cDNA human dNT-2 codes for 25.9-kDa polypeptide with typical mitochondrial leader peptide, providing structural basis two-step...

We quantify cytosolic and mitochondrial deoxyribonucleoside triphosphates (dNTPs) from four established cell lines using a recently described method for the separation of (mt) dNTPs as little 10 million cells in culture (Pontarin, G., Gallinaro, L., Ferraro, P., Reichard, Bianchi, V. (2003) Proc. Natl. Acad. Sci. U. S. A. 100, 12159–12164). In cycling concentrations phosphates thymidine, deoxycytidine, deoxyadenosine (combining mono-, di-, each case) did not differ significantly between...

Mitochondrial (mt) DNA depletion syndromes can arise from genetic deficiencies for enzymes of dNTP metabolism, operating either inside or outside mitochondria. MNGIE is caused by the deficiency cytosolic thymidine phosphorylase that degrades and deoxyuridine. The extracellular fluid patients contains 10–20 μm deoxynucleosides leading to changes in dTTP may disturb mtDNA replication. In earlier work, we suggested mt originates two distinct pathways: (i) reduction ribonucleotides cytosol (in...

Degradation of pyrimidine deoxyribonucleoside triphosphates plays a major role in the regulation their pool sizes 3T6 cells. During normal growth, these cells excrete deoxyribonucleosides (mostly deoxyuridine) into medium. When DNA strand elongation is inhibited, de novo synthesis dCTP and dTTP continues, followed by degradation deoxyribonucleotides. We now demonstrate that inhibition with hydroxyurea stops deoxyribonucleotides leads to an influx deoxyuridine from This effect appears be...

Dividing cultured cells contain much larger pools of the four dNTPs than resting cells. In both cases sizes individual are only moderately different. The same applies to mitochondrial (mt) Song et al . [Song S, Pursell ZF, Copeland WC, Longley MJ, Kunkel TA, Mathews CK (2005) Proc Natl Acad Sci USA 102:4990–4995] reported that mt rat tissues instead highly asymmetric, with dGTP pool in some being several-hundred-fold dTTP pool, and suggested asymmetry contributes increased mutagenesis during...

Mitochondrial (mt) neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disease associated with depletion, deletions, and point mutations of mtDNA. Patients lack a functional thymidine phosphorylase their plasma contains high concentrations deoxyuridine; elevation the corresponding triphosphates probably impairs normal mtDNA replication repair. To study metabolic events leading to MNGIE we used as model systems skin lung fibroblasts cultured in presence and/or...

Journal Article A cytogenetic study on workers exposed to low concentrations of benzene Get access F. Sarto, Sarto Istituto di Medicina del Lavoro, Università PadovaVia Facciolati 71, 35100 Padua Search for other works by this author on: Oxford Academic PubMed Google Scholar I. Cominato, Cominato A.M. Pinton, Pinton P.G. Brovedani, Brovedani E. Merier, Merier 1Istituto Anatomia Patologica, VeronaBorgo Roma, 37100 Verona M. Peruzzi, Peruzzi 2U.S.S.L.n.45, Asola, 46100 Mantua V. Bianchi,...