title: Unraveling the function of the two Entner-Doudoroff branches in the thermoacidophilic Crenarchaeon Sulfolobus solfataricus P2.
abstract: Sulfolobus solfataricus P2 is a thermoacidophilic archaeon that metabolizes glucose and galactose via an unusual branched Entner-Doudoroff (ED) pathway, which is characterized by a non-phosphorylative (np) and a semi-phosphorylative (sp) branch. However, so far the physiological significance of the two pathway branches is unknown. In order to address these questions two key enzymes of the branched ED pathway, the class II glycerate kinase (GK) of the np-ED branch and the 2-keto-3-deoxygluconate kinase (KDGK) of the sp-ED branch in S. solfataricus, were investigated. GK was recombinantly purified and characterized with respect to its kinetic properties. Mg(2+) dependent Sso-GK (glycerate + ATP → 2-phosphoglycerate + ADP) showed unusual regulatory properties, i.e. substrate inhibition and cooperativity by D-glycerate and ATP, and a substrate-inhibition model was established fitting closely to the experimental data. Furthermore, deletion of the sp-ED key enzyme KDGK in S. solfataricus PBL2025 resulted in a similar growth phenotype on glucose as substrate compared with the wild-type. In contrast, the mutant showed strongly increased concentrations of np-ED intermediates whereas the hexose and pentose phosphates as well as trehalose were decreased. Together the results indicate (a) that the np-ED pathway is able to compensate for the missing sp-ED branch in glucose catabolism, (b) that in addition to its catabolic function the sp-ED pathway has an additional although not essential role in providing sugar phosphates for anabolism/gluconeogenesis and (c) that GK, with its unusual regulatory properties, seems to play a major role in controlling the flux between the glycolytic np-ED and the glycolytic/gluconeogenetic sp-ED pathway.
authors.affiliation: Molecular Enzyme Technology and Biochemistry, Biofilm Centre, Faculty of Chemistry, University of Duisburg-Essen, Essen, Germany.
authors.forename: Theresa
authors.initials: T
authors.lastname: Kouril
authors.forename: Patricia
authors.initials: P
authors.lastname: Wieloch
authors.forename: Julia
authors.initials: J
authors.lastname: Reimann
authors.forename: Michaela
authors.initials: M
authors.lastname: Wagner
authors.forename: Melanie
authors.initials: M
authors.lastname: Zaparty
authors.forename: Sonja-Verena
authors.initials: SV
authors.lastname: Albers
authors.forename: Dietmar
authors.initials: D
authors.lastname: Schomburg
authors.forename: Peter
authors.initials: P
authors.lastname: Ruoff
authors.forename: Bettina
authors.initials: B
authors.lastname: Siebers
mesh_terms: D019843:Archaeal Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D003001:Cloning, Molecular; D017353:Gene Deletion; D005988:Glyceric Acids / Q000737:chemistry; D006019:Glycolysis; D006593:Hexokinase / Q000737:chemistry; D007700:Kinetics; D053858:Metabolic Networks and Pathways; D055442:Metabolome; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D048229:Sulfolobus solfataricus / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D005988:Glyceric Acids; D017853:Phosphotransferases (Alcohol Group Acceptor); D006593:Hexokinase; C020670:glycerate kinase; C021471:2-keto-3-deoxygluconokinase