The central carbohydrate metabolism of the hyperthermophilic crenarchaeote Thermoproteus tenax : pathways and insights i
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MINI-REVIEW
The central carbohydrate metabolism of the hyperthermophilic crenarchaeote Thermoproteus tenax: pathways and insights into their regulation Melanie Zaparty Æ Britta Tjaden Æ Reinhard Hensel Æ Bettina Siebers
Received: 21 December 2007 / Revised: 14 April 2008 / Accepted: 20 April 2008 / Published online: 20 May 2008 Ó Springer-Verlag 2008
Abstract Although the complexity and modifications of the archaeal central carbohydrate metabolism (CCM) are well established, the knowledge about its regulation is rather limited. The facultatively heterotrophic, hyperthermophilic crenarchaeote Thermoproteus tenax utilizes a modified version of the reversible Embden-MeyerhofParnas (EMP) and the catabolic, branched EntnerDoudoroff (ED) pathway for glucose metabolism. Glucose is completely oxidized to carbon dioxide via the oxidative tricarboxylic acid (TCA) cycle, which is supposedly used in the reductive direction for carbon dioxide fixation under autotrophic growth conditions. Elemental sulfur is used as final electron acceptor. The CCM of T. tenax has been well studied on protein level as well as on gene level by performing a focused transcriptional analysis (CCM DNA microarray). In contrast to the classical pathways found in Bacteria and Eucarya allosteric regulation seems to play a minor role, therefore emphasizing the important role of regulation on transcript level in T. tenax. Whereas the EMP pathway and the TCA cycle show a highly coordinated regulation on gene level, the catabolic, branched ED pathway reveals no strong regulation. The CCM pathways Communicated by Friedrich Widdel. M. Zaparty (&) B. Siebers Department of Chemistry, Biofilm Centre, Molecular Enzyme Technology and Biochemistry, University of Duisburg-Essen, Lotharstraße, 47057 Duisburg, Germany e-mail: [email protected] B. Tjaden R. Hensel Department of Biology and Geography, Institute of Biology, Microbiology I, University of Duisburg-Essen, Universita¨tsstraße 5, 45117 Essen, Germany
in T. tenax and the current understanding of their regulation are presented. Keywords Central carbohydrate metabolism Thermoproteus tenax Archaea Hyperthermophile Embden-Meyerhof-Parnas pathway Entner-Doudoroff pathway Regulation of metabolism Abbreviations CCM Central carbohydrate metabolism ED Entner-Doudoroff EMP Embden-Meyerhof-Parnas TCA Tricarboxylic acid
Introduction The increasing availability of archaeal genome sequence information (about 31 euryarchaeal and 17 crenarchaeal genomes; http://archaea.ucsc.edu/) reveals the basis for further insights into characteristic features of the archaeal domain. Bioinformatic and biochemical studies have shown that Archaea represent a chimera of bacterial and eucaryal features, as well as possess specific archaeal characteristics (Koonin and Galperin 2003). Classical biochemical studies together with genome-based reconstruction of archaeal metabolism and comparative genomic analyses revealed a wide diversity in archaeal metabolic pathways, which seems to be often governed by non-orthologous
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