The semi-phosphorylative Entner-Doudoroff pathway in hyperthermophilic archaea: a re-evaluation

H. Ahmed, T.J.G. Ettema, B. Tjaden, A.C.M. Geerling, J. van der Oost, B. Siebers

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100 Citations (Scopus)

Abstract

Biochemical studies have suggested that, in hyperthermophilic archaea, the metabolic conversion of glucose via the ED (Entner¿Doudoroff) pathway generally proceeds via a non-phosphorylative variant. A key enzyme of the non-phosphorylating ED pathway of Sulfolobus solfataricus, KDG (2-keto-3-deoxygluconate) aldolase, has been cloned and characterized previously. In the present study, a comparative genomics analysis is described that reveals conserved ED gene clusters in both Thermoproteus tenax and S. solfataricus. The corresponding ED proteins from both archaea have been expressed in Escherichia coli and their specificity has been identified, revealing: (i) a novel type of gluconate dehydratase (gad gene), (ii) a bifunctional 2-keto-3-deoxy-(6-phospho)-gluconate aldolase (kdgA gene), (iii) a 2-keto-3-deoxygluconate kinase (kdgK gene) and, in S. solfataricus, (iv) a GAPN (non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase; gapN gene). Extensive in vivo and in vitro enzymatic analyses indicate the operation of both the semi-phosphorylative and the non-phosphorylative ED pathway in T. tenax and S. solfataricus. The existence of this branched ED pathway is yet another example of the versatility and flexibility of the central carbohydrate metabolic pathways in the archaeal domain
Original languageEnglish
Pages (from-to)529-540
JournalBiochemical Journal
Volume390
Issue number2
DOIs
Publication statusPublished - 2005

Keywords

  • d-gluconate dehydratase
  • thermoproteus-tenax
  • sulfolobus-solfataricus
  • glyceraldehyde-3-phosphate dehydrogenase
  • escherichia-coli
  • structural basis
  • 2-keto-3-deoxygluconate aldolase
  • clostridium-pasteurianum
  • carbohydrate-metabolism
  • glucose-dehydrogenase

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