PhD conferral Dennis Botman
Aula, Vrije Universiteit Amsterdam
Visualizing cellular adaptation in budding yeast during environmental changes
Prof.dr. B. Teusink, copromotor Dr.ir. J. Goedhart
Amsterdam Institute of Molecular and Life Sciences
In the presented thesis, Dennis Botman used fluorescent proteins to study the cellular behavior of budding yeast (Saccharomyces cerevisiae). The use of these proteins allowed to read out certain important parameters for yeast: from their energy level (ATP), to the localization of important glycolytic enzymes, to the second messenger cAMP that tells a yeast cell how well it can grow in its current environment. To do this properly, Dennis first characterized which fluorescent proteins worked best in yeast and also optimized them for use in yeast. Subsequently, these best performing proteins were used to properly measure the mentioned parameters by using FRET sensors and protein tagging. The results gave a very widespread picture: a cell measured trough cAMP its conditions very accurately. We found very few cells to misinterpret their environment. In contrast, their response in ATP levels was very heterogeneous. Some showed a large response in their ATP levels, others had little or no response. We also saw localization of enzymes in cytosolic granules under certain conditions. It is still not entirely clear why these cells do this. This thesis shows that fluorescent proteins are an important tool to improve our understanding of the adaptation of yeast cells to changing environments.
Response of yeast cells having the cAMP sensor from a pyruvate to glucose transitions. Colour indicates FRET ratio (i.e. cAMP levels), depicted by the calibration bar in the upper left.