@phdthesis{Borghi2021, author = {Borghi, Gian Luca}, title = {Evolution and diversity of photosynthetic metabolism in C3, C3-C4 intermediate and C4 plants}, doi = {10.25932/publishup-52220}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-522200}, school = {Universit{\"a}t Potsdam}, pages = {163}, year = {2021}, abstract = {In C3 plants, CO2 diffuses into the leaf and is assimilated by the Calvin-Benson cycle in the mesophyll cells. It leaves Rubisco open to its side reaction with O2, resulting in a wasteful cycle known as photorespiration. A sharp fall in atmospheric CO2 levels about 30 million years ago have further increased the side reaction with O2. The pressure to reduce photorespiration led, in over 60 plant genera, to the evolution of a CO2-concentrating mechanism called C4 photosynthesis; in this mode, CO2 is initially incorporated into 4-carbon organic acids, which diffuse to the bundle sheath and are decarboxylated to provide CO2 to Rubisco. Some genera, like Flaveria, contain several species that represent different steps in this complex evolutionary process. However, the majority of terrestrial plant species did not evolve a CO2-concentrating mechanism and perform C3 photosynthesis. This thesis compares photosynthetic metabolism in several species with C3, C4 and intermediate modes of photosynthesis. Metabolite profiling and stable isotope labelling were performed to detect inter-specific differences changes in metabolite profile and, hence, how a pathway operates. The results obtained were subjected to integrative data analyses like hierarchical clustering and principal component analysis, and were deepened by correlation analyses to uncover specific metabolic features and reaction steps that were conserved or differed between species. The main findings are that Calvin-Benson cycle metabolite profiles differ between C3 and C4 species and between different C3 species, including a very different response to rising irradiance in Arabidopsis and rice. These findings confirm Calvin-Benson cycle operation diverged between C3 and C4 species and, most unexpectedly, even between different C3 species. Moreover, primary metabolic profiles supported the current C4 evolutionary model in the genus Flaveria and also provided new insights and opened up new questions. Metabolite profiles also point toward a progressive adjustment of the Calvin-Benson cycle during the evolution of C4 photosynthesis. Overall, this thesis point out the importance of a metabolite-centric approach to uncover underlying differences in species apparently sharing the same photosynthetic routes and as a valid method to investigate evolutionary transition between C3 and C4 photosynthesis.}, language = {en} } @phdthesis{Goetze2010, author = {G{\"o}tze, Jan Philipp}, title = {Influence of protein and solvent environments on quantum chemical properties of photosynthesis enzymes and photoreceptors}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-51135}, school = {Universit{\"a}t Potsdam}, year = {2010}, abstract = {This thesis contains quantum chemical models and force field calculations for the RuBisCO isotope effect, the spectral characteristics of the blue-light sensor BLUF and the light harvesting complex II. The work focuses on the influence of the environment on the corresponding systems. For RuBisCO, it was found that the isotopic effect is almost unaffected by the environment. In case of the BLUF domain, an amino acid was found to be important for the UV/vis spectrum, but unaccounted for in experiments so far (Ser41). The residue was shown to be highly mobile and with a systematic influence on the spectral shift of the BLUF domain chromophore (flavin). Finally, for LHCII it was found that small changes in the geometry of a Chlorophyll b/Violaxanthin chromophore pair can have strong influences regarding the light harvesting mechanism. Especially here it was seen that the proper description of the environment can be critical. In conclusion, the environment was observed to be of often unexpected importance for the molecular properties, and it seems not possible to give a reliable estimate on the changes created by the presence of the environment.}, language = {en} }