Regulationsmechanismen des Kohlenhydratmetabolismus in Diatomeen

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WEBER, Till, 2008. Regulationsmechanismen des Kohlenhydratmetabolismus in Diatomeen [Dissertation]. Konstanz: University of Konstanz

@phdthesis{Weber2008Regul-7104, title={Regulationsmechanismen des Kohlenhydratmetabolismus in Diatomeen}, year={2008}, author={Weber, Till}, address={Konstanz}, school={Universität Konstanz} }

terms-of-use Weber, Till 2008 Regulationsmechanismen des Kohlenhydratmetabolismus in Diatomeen application/pdf Mechanisms of regulation of the carbohydrate-metabolism in diatoms 2011-03-24T17:31:31Z deu Diatoms are unicellular, photoautotrophic organisms, which can be found in all aquatic habitats. Diatom plastids probably evolved by secondary endocytobiosis, the uptake of a eukaryotic alga into another eukaryotic host cell. In the course of evolution the endosymbiont was reduced to a cell organelle. The genome sequences of the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana recently have been sequenced.<br />The genes encoding enzymes of the Calvin cycle and the Ferredoxin/Thioredoxin-system were identified, and the localisation of the respective proteins was predicted by bioinformatic tools. Fusion of the respective presequences to GFP and the subsequent expression of the constructs in P. tricornutum demonstrated that the four Fructose-1,6-bisphosphatases, one Phosphogluconat Lactonase, one Ferredoxin/Thioredoxin Reductase, and the Thioredoxins F, M and Y are localised in the plastids. One 6-Phospho-Gluconolactone Dehydrogenase and one Thioredoxin H are possibly localised in the periplastidic space. The Seduheptulose-1,7-bisphosphatase, one Fructose-1,6-bisphosphatase, one NADPH-depended Thioredoxin Reductase and one Thioredoxin H are localised in the Cytosol. It was shown for P. tricornutum and T. pseudonana that the oxidative pentose phosphate pathway (OPP) is relocated to the cytosol. As a result of this transfer, the Seduheptulose-1,7-bisphosphatase is possibly physiologically integrated in the OPP. In P. tricornutum the regulation of the plastidic RPP via Thioredoxin F is limited to the Fructose-1,6-bisphosphatase. Two of the four isoforms can be probably regulated via the cysteine residues in the regulative centre. The kinetic properties of the Fructose-1,6-bisphosphatases in the crude cell extract of P. tricornutum is similar to other plastidic Fructose-1,6-bisphosphatases of higher plants. It was demonstrated that the transcription levels of nuclear encoded genes of the OPP and RPP are not changing during by the diurnal cell cycle. Some possible target proteins of Thioredoxin have been collected by a Thioredoxin affinity chromatography and identificated by mass spectrometric analyses. Weber, Till 2011-03-24T17:31:31Z

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