The Archaea represent a domain of organisms that are phylogenetically distinct to the Bacteria and Eucarya and harbor many metabolic pathways that differ to previously recognized classical pathways in bacteria and eukaryotes. Many sugar-utilizing Archaea utilize a modified version of the Embden-Meyerhoff (EM) and/or the Entner-Doudoroff pathway. Unique features of the modified EM pathway include the presence of an ADP-dependent glucokinase and phosphofructokinase, and a glyceraldehyde 3-phosphate:ferredoxin oxidoreductase that catalyzes the single-step oxidation of GAP to 3-phosphoglycerate. A structurally novel glucose phosphate isomerase and archaeal class IA fructose-1,6-bisphosphate aldolase have also been identified. Based on the genome sequences of the Archaea, there are many cases in which a particular metabolic pathway seems to be absent or incomplete. The search for these �missing� pathways or enzymes has been an exciting field of research in the Archaea, and has led to the discovery of structurally novel enzymes or enzymes with novel activity. Until now, we have been focused on the metabolism of Thermococcus kodakarensis. T. kodakarensis is a hyperthermophilic archaeon isolated from Kodakara Island, Japan. The organism is an obligate anaerobe and heterotroph, utilizing a wide range of organic compounds including peptides/amino acids, starch and maltooligosaccharides, and organic acids such as pyruvate. By searching for missing genes, we have identified a structurally novel fructose-1,6-bisphosphatase, a key enzyme in gluconeogenesis, and enzymes with novel activity, such as AMP phosphorylase and ribose-1,5-bisphosphate isomerase. Here we will present our results concerning the enzymes involved in coenzyme A biosynthesis in T. kodakarensis.

Novel enzymes and pathways in the Archaea

248th National Meeting (2014)

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