Graduate Students Mini Symposium I 2023

Program
13:15 h Luca Schulz - AG Erb
"Evolution of increased complexity and specificity at the dawn of form I Rubiscos”

The evolution of ribulose-1,5-bisphosphate carboxylase/oxygenases that discriminate strongly between their substrate carbon dioxide and the undesired side substrate dioxygen was an important event for photosynthetic organisms adapting to an oxygenated environment. We use ancestral sequence reconstruction to recapitulate this event. We show that Rubisco increased its specificity and carboxylation efficiency through the gain of an accessory subunit before atmospheric oxygen was present. Using structural and biochemical approaches, we retrace how this subunit was gained and became essential. Our work illuminates the emergence of an adaptation to rising ambient oxygen levels and sheds light on the determinants of specificity in Rubisco.

13:45 h Robin Köhler - AG Murray
"Using High throughput image analysis to investigate the ParABS system of the F-Plasmid"

The ParABS system is a partition system which segregates both chromosomal and extra chromosomal DNA. Low copy number plasmids, like the F-Plasmid, use the ParABS system to ensure their stability. The ParABS system places the plasmids equidistantly along the long axis of the cell. This ensures that daughter cells inherent the same number of plasmids. It is not fully known how such a system, only consisting of two proteins (ParA/ParB) and one sequence (parS), accomplishes this task. Using high throughput image analysis I am investigating the dynamics of ParA and ParB to infer the inner mechanism of the system.

14:15 h Sebastian Pöhl - AG Thanbichler
"A multi-protein network responsible for the establishment and fine-tuning of the curved cell shape of Rhodospirillum rubrum"

Bacteria come in many different shapes, which help them to move efficiently in the ecological niches they inhabit and thus ensure optimal fitness and survival. The mechanisms underlying morphogenesis in curved bacteria is a particularly interesting field of research, because in order to achieve a curved shape, the symmetry of the cells needs to be broken. Previous studies of curved model organisms, such as V. cholerae, H. pylori and C. crescentus, have revealed that bacteria have evolved a variety of fundamentally different shaping mechanisms. In our analysis of the morphogenetic pathway of the alphaproteobacterium Rhodospirillum rubrum, we have identified and characterized multiple proteins that are involved in the establishment and maintenance of its curved cell shape. Some of them, including spatially organized porins that position a conserved outer-membrane lipoprotein, are crucial for the establishment of cell curvature. Other proteins appear to be involved in fine-tuning the degree of curvature by exerting counteracting forces. Together, these factors form a novel and, in large part, conserved morphogenetic protein network that extends from the cytoplasm to the outer membrane and likely mediates the curved cell morphology in many spiral-shaped members of the family Rhodospirillaceae.