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.

• A non-carboxylating pentose bisphosphate pathway in halophilic archaea.

  Sato T., Utashima S.H., Yoshii Y., Hirata K., Kanda S., Onoda Y., Jin J.Q., Xiao S., Minami R., Fukushima H., Noguchi A., Manabe Y., Fukase K., Atomi H.

  Bacteria and Eucarya utilize the non-oxidative pentose phosphate pathway to direct the ribose moieties of nucleosides to central carbon metabolism. Many archaea do not possess this pathway, and instead, Thermococcales utilize a pentose bisphosphate pathway involving ribose-1,5-bisphosphate (R15P) ... >> More

  Bacteria and Eucarya utilize the non-oxidative pentose phosphate pathway to direct the ribose moieties of nucleosides to central carbon metabolism. Many archaea do not possess this pathway, and instead, Thermococcales utilize a pentose bisphosphate pathway involving ribose-1,5-bisphosphate (R15P) isomerase and ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco). Intriguingly, multiple genomes from halophilic archaea seem only to harbor R15P isomerase, and do not harbor Rubisco. In this study, we identify a previously unrecognized nucleoside degradation pathway in halophilic archaea, composed of guanosine phosphorylase, ATP-dependent ribose-1-phosphate kinase, R15P isomerase, RuBP phosphatase, ribulose-1-phosphate aldolase, and glycolaldehyde reductase. The pathway converts the ribose moiety of guanosine to dihydroxyacetone phosphate and ethylene glycol. Although the metabolic route from guanosine to RuBP via R15P is similar to that of the pentose bisphosphate pathway in Thermococcales, the downstream route does not utilize Rubisco and is unique to halophilic archaea. << Less

  Commun. Biol. 5:1290-1290(2022) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.