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| 2. |
- Ettema, Thijs J. G., et al.
(författare)
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The non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase (GAPN) of Sulfolobus solfataricus : a key-enzyme of the semi-phosphorylative branch of the Entner-Doudoroff pathway
- 2008
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Ingår i: Extremophiles. - : Springer Science and Business Media LLC. - 1431-0651 .- 1433-4909. ; 12:1, s. 75-88
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Tidskriftsartikel (refereegranskat)abstract
- Archaea utilize a branched modification of the classical Entner-Doudoroff (ED) pathway for sugar degradation. The semi-phosphorylative branch merges at the level of glyceraldehyde 3-phosphate (GAP) with the lower common shunt of the Emden-Meyerhof-Parnas pathway. In Sulfolobus solfataricus two different GAP converting enzymes-classical phosphorylating GAP dehydrogenase (GAPDH) and the non-phosphorylating GAPDH (GAPN)-were identified. In Sulfolobales the GAPN encoding gene is found adjacent to the ED gene cluster suggesting a function in the regulation of the semi-phosphorylative ED branch. The biochemical characterization of the recombinant GAPN of S. solfataricus revealed that-like the well-characterized GAPN from Thermoproteus tenax-the enzyme of S. solfataricus exhibits allosteric properties. However, both enzymes show some unexpected differences in co-substrate specificity as well as regulatory fine-tuning, which seem to reflect an adaptation to the different lifestyles of both organisms. Phylogenetic analyses and database searches in Archaea indicated a preferred distribution of GAPN (and/or GAP oxidoreductase) in hyperthermophilic Archaea supporting the previously suggested role of GAPN in metabolic thermoadaptation. This work suggests an important role of GAPN in the regulation of carbon degradation via modifications of the EMP and the branched ED pathway in hyperthermophilic Archaea.
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| 3. |
- Reimann, Julia, et al.
(författare)
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Archaeal Signal Transduction : Impact of Protein Phosphatase Deletions on Cell Size, Motility, and Energy Metabolism in Sulfolobus acidocaldarius
- 2013
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Ingår i: Molecular & Cellular Proteomics. - : Elsevier BV. - 1535-9476 .- 1535-9484. ; 12:12, s. 3908-3923
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the in vitro and in vivo functions of the only two identified protein phosphatases, Saci-PTP and Saci-PP2A, in the crenarchaeal model organism Sulfolobus acidocaldarius were investigated. Biochemical characterization revealed that Saci-PTP is a dual-specific phosphatase (against pSer/pThr and pTyr), whereas Saci-PP2A exhibited specific pSer/pThr activity and inhibition by okadaic acid. Deletion of saci_pp2a resulted in pronounced alterations in growth, cell shape and cell size, which could be partially complemented. Transcriptome analysis of the three strains (Δsaci_ptp, Δsaci_pp2a and the MW001 parental strain) revealed 155 genes that were differentially expressed in the deletion mutants, and showed significant changes in expression of genes encoding the archaella (archaeal motility structure), components of the respiratory chain and transcriptional regulators. Phosphoproteome studies revealed 801 unique phosphoproteins in total, with an increase in identified phosphopeptides in the deletion mutants. Proteins from most functional categories were affected by phosphorylation, including components of the motility system, the respiratory chain, and regulatory proteins. In the saci_pp2a deletion mutant the up-regulation at the transcript level, as well as the observed phosphorylation pattern, resembled starvation stress responses. Hypermotility was also observed in the saci_pp2a deletion mutant. The results highlight the importance of protein phosphorylation in regulating essential cellular processes in the crenarchaeon S. acidocaldarius.
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| 4. |
- Wang, Kun, et al.
(författare)
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A bacterial-like FadR transcription factor regulates fatty acid metabolism in the archaeal model organism Sulfolobus acidocaldarius
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In accordance with the important biological roles of fatty acids, their metabolism is under complex regulation in bacteria and eukaryotes. In contrast, although certain archaea also appear to metabolize fatty acids, nothing is known about the regulation of the underlying pathways in these organisms. Here we show that the crenarchaeon Sulfolobus acidocaldarius harbors a bacterial-type TetR-family transcriptional regulator FadRSa and that it is involved in regulation of fatty acid metabolism. Functional and structural analyses show that the regulator binds semi-palindromic recognition sites in two distinct operator-dependent binding modes and that binding of fatty acyl-CoA molecules causes dissociation of FadRSa-DNA complexes by inducing conformational changes in the protein. Curiously, despite the similarity in overall structure and mechanisms between FadRSa and bacterial TetR-family FadR regulators, we reveal a fundamentally different acyl-CoA binding mode that suggests convergent evolution. Genome-wide transcriptomic and FadRSa-specific chromatin immunoprecipitation analyses further demonstrate that the transcription factor acts as a local repressor of a gene cluster comprising 23 open reading frames that encode lipases, beta-oxidation enzymes and acetyl-CoA acetyltransferases. We conclude that lipid degradation and fatty acid metabolism in S. acidocaldarius is subject to an acyl-CoA responsive transcriptional repression by a homolog of bacterial TetR-family FadR proteins of which the regulatory mechanism suggests that the regulated gene cluster minimally has a catabolic function.
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| 5. |
- Wang, Kun, et al.
(författare)
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A TetR-family transcription factor regulates fatty acid metabolism in the archaeal model organism Sulfolobus acidocaldarius
- 2019
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Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Fatty acid metabolism and its regulation are known to play important roles in bacteria and eukaryotes. By contrast, although certain archaea appear to metabolize fatty acids, the regulation of the underlying pathways in these organisms remains unclear. Here, we show that a TetR-family transcriptional regulator (FadR(sa)) is involved in regulation of fatty acid metabolism in the crenarchaeon Sulfolobus acidocaldarius. Functional and structural analyses show that FadR(sa) binds to DNA at semi-palindromic recognition sites in two distinct stoichiometric binding modes depending on the operator sequence. Genome-wide transcriptomic and chromatin immunoprecipitation analyses demonstrate that the protein binds to only four genomic sites, acting as a repressor of a 30-kb gene cluster comprising 23 open reading frames encoding lipases and beta-oxidation enzymes. Fatty acyl-CoA molecules cause dissociation of FadR(sa) binding by inducing conformational changes in the protein. Our results indicate that, despite its similarity in overall structure to bacterial TetR-family FadR regulators, FadR(sa) displays a different acyl-CoA binding mode and a distinct regulatory mechanism.
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