Project Details
Projekt
The network of two circadian oscillators in a cyanobacterium
Subject Area
Plant Biochemistry and Biophysics
Term
since 2025
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 573342561
Every day, Earth completes a rotation on its axis, creating a cycle of day and night. Both plants and animals can anticipate this cycle through an internal genetically programmed clock. Even microorganisms that can reproduce more quickly than once a day possess an internal clock. Photosynthetic cyanobacteria have such a biological, circadian clock that enables them to predict the transition between day and night and synchronise their activities accordingly. In cyanobacteria, the clock comprises three distinct Kai proteins. KaiA stimulates the core protein KaiC, promoting its autophosphorylation, whereas KaiB counteracts KaiA, leading to the dephosphorylation of KaiC. This process of KaiC phosphorylation and dephosphorylation regulates the circadian rhythm of cellular activities. However, several cyanobacteria contain more than this standard set of Kai proteins, and their functions remain unknown. Notably, the model cyanobacterium we will study in the current proposal, possesses, in addition to a canonical kaiABC gene cluster, two extra kaiB and kaiC homologs. Recently, we discovered a novel KaiA homolog and demonstrated that two complete and interconnected KaiABC systems can function within a single cell, highlighting the intricate complexity of this new circadian system. We hypothesize that the two oscillator systems are associated with different input and output factors that we intend to identify. Using backscatter signals of bacterial cultures and oscillation in microscopic parameters of single cells, we established novel methods to readily detect circadian rhythms. We will use these analytical tools to study the input and output factors that connect the oscillators with the environment and transfer time information into cellular activities. We will determine whether there are specific elements interacting with only one oscillator or whether there are common input and output pathways. Screening using backscatter measurements and microfluidics will reveal more information about the synchronisation and entrainment of timing systems. Our goal is to achieve a mechanistic understanding of how both oscillator systems interact within a cell and how they regulate circadian rhythms in response to environmental factors.
DFG Programme
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