Cyanobacterial circadian clock in vitro and in vivo

Abstract

Circadian rhythms are intrinsic biological rhythms that have a period close to 24 hours. Prokaryotic cyanobacteria are the simplest organisms that show robust circadian rhythms, and are the only organisms that have a circadian rhythm reconstituted in vitro in test tubes in the presence of ATP. This thesis is focused on studying the mechanism of the core circadian clockwork in the cyanobacterium Synechococcus elongatus PCC 7942. In this dissertation, I explore the mechanism of the circadian rhythm in cyanobacteria with both in vitro and in vivo studies. I elucidate the essential pattern of dynamic protein- protein interactions among three identified core clock Kai proteins, and define the relationship between the traditional TTFL (transcription translation feedback loop) model and the PTO (post translational oscillator) model within this strain. In addition, a KaiC monomer exchange phenomenon is studied to further investigate the robustness of the rhythm.