Organellar metabolic networks in Stramenopiles (Heterokonts)

• Applicant: Professor Dr. Peter Kroth
• Subject Area: Plant Biochemistry and Biophysics
• Term: from 2008 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 105758702

Stramenopiles, including diatoms and the related colourless oomycetes, evolved by secondary endosymbiosis. This process resulted in metabolic and genetic re-organization and changes in the compartmentation due to the endosymbiotic fusion of two formerly independent eukaryotic cells. Very little is known about the physiology and biochemistry of mitochondria of Stramenopiles, especially considering that the origin of the eukaryotic cell which served as host for secondary endocytobiosis is still unclear. In this project we want to study the interaction between cytosol, plastids and the mitochondria in diatoms with respect to their carbohydrate metabolism. Previous work has demonstrated that isoenzymes of each enzyme of the second half of the glycolysis are targeted to the mitochondria. To study these parallel pathways we would like to optimize the preparation of mitochondria from diatoms and oomycetes to measure activities of the respective mitochondrial enzymes. We want to find out whether both (mitochondrial and cytosolic) pathways are functional in diatoms and whether the cells can shift between both pathways, responding to changes of the internal or external conditions, by performing qPCR analysis to determine the expression of individual genes. The variation of the protein levels will be analysed by Western blots and the changes of activity by enzymatic analyses. Individual enzymes will be overexpressed in E.coli and characterized enzymatically. By genetic approaches individual genes in Phaeodactylum tricornutum will be silenced using inducible promoters followed by a physiological characterization of the mutants.

• DFG Programme: Research Grants