Publications

• A Phosphofructokinase Homolog from Pyrobaculum calidifontis Displays Kinase Activity towards Pyrimidine Nucleosides and Ribose 1-Phosphate.

  Aziz I., Bibi T., Rashid N., Aono R., Atomi H., Akhtar M.

  The genome of the hyperthermophilic archaeon <i>Pyrobaculum calidifontis</i> contains an open reading frame, Pcal_0041, annotated as encoding a PfkB family ribokinase, consisting of phosphofructokinase and pyrimidine kinase domains. Among the biochemically characterized enzymes, the Pcal_0041 prot ... >> More

  The genome of the hyperthermophilic archaeon <i>Pyrobaculum calidifontis</i> contains an open reading frame, Pcal_0041, annotated as encoding a PfkB family ribokinase, consisting of phosphofructokinase and pyrimidine kinase domains. Among the biochemically characterized enzymes, the Pcal_0041 protein was 37% identical to the phosphofructokinase (Ape_0012) from <i>Aeropyrum pernix</i>, which displayed kinase activity toward a broad spectrum of substrates, including sugars, sugar phosphates, and nucleosides, and 36% identical to a phosphofructokinase from <i>Desulfurococcus amylolyticus</i> To examine the biochemical function of the Pcal_0041 protein, we cloned and expressed the gene and purified the recombinant protein. Although the Pcal_0041 protein contained a putative phosphofructokinase domain, it exhibited only low levels of phosphofructokinase activity. The recombinant enzyme catalyzed the phosphorylation of nucleosides and, to a lower extent, sugars and sugar phosphates. Surprisingly, among the substrates tested, the highest activity was detected with ribose 1-phosphate (R1P), followed by cytidine and uridine. The catalytic efficiency (<i>k</i>_cat/<i>K_m</i> ) toward R1P was 11.5 mM^-1 · s^-1 ATP was the most preferred phosphate donor, followed by GTP. Activity measurements with cell extracts of <i>P. calidifontis</i> indicated the presence of nucleoside phosphorylase activity, which would provide the means to generate R1P from nucleosides. The study suggests that, in addition to the recently identified ADP-dependent ribose 1-phosphate kinase (R1P kinase) in <i>Thermococcus kodakarensis</i> that functions in the pentose bisphosphate pathway, R1P kinase is also present in members of the Crenarchaeota.<b>IMPORTANCE</b> The discovery of the pentose bisphosphate pathway in <i>Thermococcus kodakarensis</i> has clarified how this archaeon can degrade nucleosides. Homologs of the enzymes of this pathway are present in many members of the Thermococcales, suggesting that this metabolism occurs in these organisms. However, this is not the case in other archaea, and degradation mechanisms for nucleosides or ribose 1-phosphate are still unknown. This study reveals an important first step in understanding nucleoside metabolism in Crenarchaeota and identifies an ATP-dependent ribose 1-phosphate kinase in <i>Pyrobaculum calidifontis</i> The enzyme is structurally distinct from previously characterized archaeal members of the ribokinase family and represents a group of proteins found in many crenarchaea. << Less

  J Bacteriol 200:e00284-18(2018) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Structural basis for the specificity, catalysis, and regulation of human uridine-cytidine kinase.

  Suzuki N.N., Koizumi K., Fukushima M., Matsuda A., Inagaki F.

  Uridine-cytidine kinase (UCK) catalyzes the phosphorylation of uridine and cytidine and activates pharmacological ribonucleoside analogs. Here we present the crystal structures of human UCK alone and in complexes with a substrate, cytidine, a feedback inhibitor, CTP or UTP, and with phosphorylatio ... >> More

  Uridine-cytidine kinase (UCK) catalyzes the phosphorylation of uridine and cytidine and activates pharmacological ribonucleoside analogs. Here we present the crystal structures of human UCK alone and in complexes with a substrate, cytidine, a feedback inhibitor, CTP or UTP, and with phosphorylation products, CMP and ADP, respectively. Free UCK takes an alpha/beta mononucleotide binding fold and exists as a homotetramer with 222 symmetry. Upon inhibitor binding, one loop region was loosened, causing the UCK tetramer to be distorted. Upon cytidine binding, a large induced fit was observed at the uridine/cytidine binding site, which endows UCK with a strict specificity for pyrimidine ribonucleosides. The first UCK structure provided the structural basis for the specificity, catalysis, and regulation of human uridine-cytidine kinase, which give clues for the design of novel antitumor and antiviral ribonucleoside analogs that inhibit RNA synthesis. << Less

  Structure 12:751-764(2004) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Reaction of human UMP-CMP kinase with natural and analog substrates.

  Pasti C., Gallois-Montbrun S., Munier-Lehmann H., Veron M., Gilles A.M., Deville-Bonne D.

  UMP-CMP kinase catalyses an important step in the phosphorylation of UTP, CTP and dCTP. It is also involved in the necessary phosphorylation by cellular kinases of nucleoside analogs used in antiviral therapies. The reactivity of human UMP-CMP kinase towards natural substrates and nucleotide analo ... >> More

  UMP-CMP kinase catalyses an important step in the phosphorylation of UTP, CTP and dCTP. It is also involved in the necessary phosphorylation by cellular kinases of nucleoside analogs used in antiviral therapies. The reactivity of human UMP-CMP kinase towards natural substrates and nucleotide analogs was reexamined. The expression of the recombinant enzyme and conditions for stability of the enzyme were improved. Substrate inhibition was observed for UMP and CMP at concentrations higher than 0.2 mm, but not for dCMP. The antiviral analog l-3TCMP was found to be an efficient substrate phosphorylated into l-3TCDP by human UMP-CMP kinase. However, in the reverse reaction, the enzyme did not catalyse the addition of the third phosphate to l-3TCDP, which was rather an inhibitor. By molecular modelling, l-3TCMP was built in the active site of the enzyme from Dictyostelium. Human UMP-CMP kinase has a relaxed enantiospecificity for the nucleoside monophosphate acceptor site, but it is restricted to d-nucleotides at the donor site. << Less

  Eur J Biochem 270:1784-1790(2003) [PubMed] [EuropePMC]

• Regulation of enzymic activity by metabolites. I. Uridine-cytidine kinase of Novikoff ascites rat tumor.

  Orengo A.

  J Biol Chem 244:2204-2209(1969) [PubMed] [EuropePMC]