Chlamydia trachomatis is an obligate intracellular bacterium that is dependent on its host cell for nucleotides. Chlamydia imports ribonucleotide triphosphates (NTPs) but not deoxyribonucleotide triphosphates (dNTPs) and instead uses ribonucleotide reductase to convert imported ribonucleotides into deoxyribonucleotides for DNA synthesis. The genes encoding ribonucleotide reductase have been rec...

Two subtypes of class III anaerobic ribonucleotide reductases (RNRs) studied so far couple the reduction of ribonucleotides to the oxidation of formate, or the oxidation of NADPH via thioredoxin and thioredoxin reductase. Certain methanogenic archaea contain a phylogenetically distinct third subtype of class III RNR, with distinct active-site residues. Here we report the cloning and recombinant...

The protein glutaredoxin, required for GSH-dependent ribonucleotide reduction, has been purified to homogeneity from calf thymus. The preparative method consisted of ammonium sulfate precipitation and three chromatography steps on DEAEkellulose, Sephadex G-50, and CM-Sepharose. Calf thymus glutaredoxin was assayed on the basis of its inherent GSH-disulfide transhydrogenase activity. Glutaredoxi...

While investigating the basis for marked natural asymmetries in deoxyribonucleoside triphosphate (dNTP) pools in mammalian cells, we observed that culturing V79 hamster lung cells in a 2% oxygen atmosphere causes 2-3-fold expansions of the dATP, dGTP, and dTTP pools, whereas dCTP declines by a comparable amount. Others have made similar observations and have proposed that, because O(2) is requi...

Ribonucleoside diphosphate reductase consists of two nonidentical subunits, proteins Bl and B2. The enzyme catalyzes the reduction of ribonucleotides to the corresponding deoxyribonucleotides. The electrons required in this reduction are transported from NADPH via a flavoprotein, thioredoxin reductase, to a low molecular weight protein, thioredoxin. The reduced form of thioredoxin acts as hydro...