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Davide Dal’Bo

Molecular actors of Chloroplast-Mitochondrion energetic interactions in the marine diatom Phaeodactylum tricornutum

Published on 29 November 2019
Thesis presented November 29, 2019

Abstract:
To produce the energy needed for cell metabolism, eukaryotic photosynthetic organisms rely on two organelles: the chloroplast and the mitochondrion. The former converting light energy into chemical energy, the latter performing cell respiration. Since both organelles have overlapping function, their activities need to be regulated. While in plants and green algae they seem to work overall independently according to environmental conditions, like light and sugar availability, in Diatoms the direct exchange of ATP and NADPH between these two organelles are essential for the cell’s survival. Although the physiology of this energetic crosstalk is well established, the molecular actors of this process are still unknown. During this PhD project, I have selected four candidate proteins, which turned out to play a role the organelles’ cross talk mechanisms. These are transporters predicted to be located within the chloroplast envelope and the inner membrane of the mitochondrion. To understand their physiological role, we compared the photosynthetic performances of the wildtype and the mutant strains with spectroscopic and fluorescence approaches, while the respiration was quantified measuring the oxygen evolution rates.
The observed differences suggest that the selected transporters play a role the chloroplast-mitochondrion crosstalk and that other proteins might be involved in this regulative process.
The further characterization of these transporters might also validate them as possible targets to improve algal biomass productivity for biotech, promoting the simultaneous use of respiration and photosynthesis (mixotrophy).

Keywords:
algae, mitochondrion, chloroplast

On-line thesis.