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Article: Unraveling the function of the two Entner-Doudoroff branches in the thermoacidophilic Crenarchaeon Sulfolobus solfataricus P2.
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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 both pathway branches is unknown. In order to address these question two key enzymes of the branched ED pathway, the class II glycerate kinase (GK) of the np-ED 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 to 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 that (i) the np-ED pathway is able to compensate for the missing sp-ED branch in glucose catabolism, (ii) 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 (iii) that GK, with its unusual regulatory properties seems to play a major role in controlling the flux between the glycolytic np-ED and glycolytic/gluconeogentic sp-ED pathway. © 2012 The Authors Journal compilation © 2012 FEBS.FEBS Journal 12/2012; · 3.79 Impact Factor -
Article: Functional curation of the Sulfolobus solfataricus P2 and S. acidocaldarius 98-3 complete genome sequences.
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ABSTRACT: The thermoacidophiles Sulfolobus solfataricus P2 and S. acidocaldarius 98-3 are considered key model organisms representing a major phylum of the Crenarchaeota. Because maintaining current, accurate genome information is indispensable for modern biology, we have updated gene function annotation using the arCOGs database, plus other available functional, structural and phylogenetic information. The goal of this initiative is continuous improvement of genome annotation with the support of the Sulfolobus research community.Extremophiles 09/2011; 15(6):711-2. · 2.94 Impact Factor -
Article: "Hot standards" for the thermoacidophilic archaeon Sulfolobus solfataricus.
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ABSTRACT: Within the archaea, the thermoacidophilic crenarchaeote Sulfolobus solfataricus has become an important model organism for physiology and biochemistry, comparative and functional genomics, as well as, more recently also for systems biology approaches. Within the Sulfolobus Systems Biology ("SulfoSYS")-project the effect of changing growth temperatures on a metabolic network is investigated at the systems level by integrating genomic, transcriptomic, proteomic, metabolomic and enzymatic information for production of a silicon cell-model. The network under investigation is the central carbohydrate metabolism. The generation of high-quality quantitative data, which is critical for the investigation of biological systems and the successful integration of the different datasets, derived for example from high-throughput approaches (e.g., transcriptome or proteome analyses), requires the application and compliance of uniform standard protocols, e.g., for growth and handling of the organism as well as the "-omics" approaches. Here, we report on the establishment and implementation of standard operating procedures for the different wet-lab and in silico techniques that are applied within the SulfoSYS-project and that we believe can be useful for future projects on Sulfolobus or (hyper)thermophiles in general. Beside established techniques, it includes new methodologies like strain surveillance, the improved identification of membrane proteins and the application of crenarchaeal metabolomics.Extremophiles 10/2009; 14(1):119-42. · 2.94 Impact Factor -
Article: SulfoSYS (Sulfolobus Systems Biology): towards a silicon cell model for the central carbohydrate metabolism of the archaeon Sulfolobus solfataricus under temperature variation.
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ABSTRACT: SulfoSYS (Sulfolobus Systems Biology) focuses on the study of the CCM (central carbohydrate metabolism) of Sulfolobus solfataricus and its regulation under temperature variation at the systems level. In Archaea, carbohydrates are metabolized by modifications of the classical pathways known from Bacteria or Eukarya, e.g. the unusual branched ED (Entner-Doudoroff) pathway, which is utilized for glucose degradation in S. solfataricus. This archaeal model organism of choice is a thermoacidophilic crenarchaeon that optimally grows at 80 degrees C (60-92 degrees C) and pH 2-4. In general, life at high temperature requires very efficient adaptation to temperature changes, which is most difficult to deal with for organisms, and it is unclear how biological networks can withstand and respond to such changes. This integrative project combines genomic, transcriptomic, proteomic and metabolomic, as well as kinetic and biochemical information. The final goal of SulfoSYS is the construction of a silicon cell model for this part of the living cell that will enable computation of the CCM network. In the present paper, we report on one of the first archaeal systems biology projects.Biochemical Society Transactions 03/2009; 37(Pt 1):58-64. · 3.71 Impact Factor -
Article: Volatilisation of metals and metalloids: an inherent feature of methanoarchaea?
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ABSTRACT: As shown by recent studies, anaerobic members of Archaea and Bacteria are involved in processes that transform ionic species of metals and metalloids (arsenic, antimony, bismuth, selenium, tellurium and mercury) into volatile and mostly toxic derivatives (mainly methyl derivatives or hydrides). Since the fact that these transformations proceed in both environmental settings and in parts of the human body, we have to consider that these processes also interfere directly with human health. The diversity of the volatile derivatives produced and their emission rates were significantly higher in methanoarchaeal than in bacterial strains, which supports the pivotal role of methanoarchaea in transforming metals and metalloids (metal(loid)s) into their volatile derivatives. Compared with methanoarchaea, 14 anaerobic bacterial strains showed a significantly restricted spectrum of volatilised derivatives and mostly lower production rates of volatile bismuth and selenium derivatives. Since methanoarchaea isolated from the human gut (Methanosphaera stadtmanae, Methanobrevibacter smithii) showed a higher potential for metal(loid) derivatisation compared to bacterial gut isolates, we assume that methanoarchaea in the human gut are mainly responsible for the production of these volatile derivatives. The observation that trimethylbismuth ((CH(3))(3)Bi), the main volatile derivative of bismuth produced in human feces, inhibited growing cultures of Bacteroides thetaiotaomicron, a representative member of the human physiological gut flora, suggests that these volatiles exert their toxic effects on human health not only by direct interaction with host cells but also by disturbing the physiological gut microflora.Systematic and Applied Microbiology 07/2008; 31(2):81-7. · 3.37 Impact Factor
