Publications

• The phosphofructokinase-B (MJ0406) from Methanocaldococcus jannaschii represents a nucleoside kinase with a broad substrate specificity.

  Hansen T., Arnfors L., Ladenstein R., Schoenheit P.

  Recently, unusual non-regulated ATP-dependent 6-phosphofructokinases (PFK) that belong to the PFK-B family have been described for the hyperthermophilic archaea Desulfurococcus amylolyticus and Aeropyrum pernix. Putative homologues were found in genomes of several archaea including the hyperthermo ... >> More

  Recently, unusual non-regulated ATP-dependent 6-phosphofructokinases (PFK) that belong to the PFK-B family have been described for the hyperthermophilic archaea Desulfurococcus amylolyticus and Aeropyrum pernix. Putative homologues were found in genomes of several archaea including the hyperthermophilic archaeon Methanocaldococcus jannaschii. In this organism, open reading frame MJ0406 had been annotated as a PFK-B sugar kinase. The gene encoding MJ0406 was cloned and functionally expressed in Escherichia coli. The purified recombinant enzyme is a homodimer with an apparent molecular mass of 68 kDa composed of 34 kDa subunits. With a temperature optimum of 85 degrees C and a melting temperature of 90 degrees C, the M. jannaschii nucleotide kinase represents one of the most thermoactive and thermostable members of the PFK-B family described so far. The recombinant enzyme was characterized as a functional nucleoside kinase rather than a 6-PFK. Inosine, guanosine, and cytidine were the most effective phosphoryl acceptors. Besides, adenosine, thymidine, uridin and xanthosine were less efficient. Extremely low activity was found with fructose-6-phosphate. Further, the substrate specificity of closely related PFK-Bs from D. amylolyticus and A. pernix were reanalysed. << Less

  Extremophiles 11:105-114(2007) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• 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.

• A pentose bisphosphate pathway for nucleoside degradation in Archaea.

  Aono R., Sato T., Imanaka T., Atomi H.

  Owing to the absence of the pentose phosphate pathway, the degradation pathway for the ribose moieties of nucleosides is unknown in Archaea. Here, in the archaeon Thermococcus kodakarensis, we identified a metabolic network that links the pentose moieties of nucleosides or nucleotides to central c ... >> More

  Owing to the absence of the pentose phosphate pathway, the degradation pathway for the ribose moieties of nucleosides is unknown in Archaea. Here, in the archaeon Thermococcus kodakarensis, we identified a metabolic network that links the pentose moieties of nucleosides or nucleotides to central carbon metabolism. The network consists of three nucleoside phosphorylases, an ADP-dependent ribose-1-phosphate kinase and two enzymes of a previously identified NMP degradation pathway, ribose-1,5-bisphosphate isomerase and type III ribulose-1,5-bisphosphate carboxylase/oxygenase. Ribose 1,5-bisphosphate and ribulose 1,5-bisphosphate are intermediates of this pathway, which is thus designated the pentose bisphosphate pathway. << Less

  Nat. Chem. Biol. 11:355-360(2015) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• 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.