Project 1A

Metabolic oscillations in photosynthetic organisms can occur on many timescales. Plants, eucaryotic algae and cyanobacteria have to switch their metabolism between photosynthesis and respiration depending on lighting conditions. Endogeneous clocks that allow a preparation for daily and seasonal (photoperiodic) cycles are known for many species. However, details about the coupling between energy metabolism and other cyclic processes such as the cell cycle are not fully understood.

In this project we investigate periodic processes in oxygen and carbon dioxide metabolism on different timescales. Working with cyanobacteria and diatoms as model organisms, we address the following questions: Are patterns in oxygen production and consumption regulated by internal clocks or external light cues? Which genes and enzymes influence oxygen metabolism?  Is there a coupling to the cell cycle? Is there a common reduced  general mechanism that may be equally applied to cyanobacteria, eucaryotic algae and higher plants? How do we model such a general mechanism?

Bringing expertises from different cyanobacteria and eucaryotic algae, experiment and modeling together, we aim at an understanding of the adaption of aquatic photoautotrophs to changing light cycles.

Approach and Methods

We recently established an Escherichia coli based over-expression system for isolation of the PdfR in milligramm amounts to examine its biophysics. For biophysical studies, we also developed protocols for solubilizing PdfR in detergent micelles and for the insertion of PdfR into lipid nanodiscs, which serve as model membranes. In this project, we will examine the stability of PdfR and the binding of Pdf using a range of biophysical methods. A focus will be on the site-directed spectroscopic labeling of the PdfR to confirm the predicted structure, the binding site, and to examine structure-function relationships.