A Molecular Dynamics Study of the Cyanobacterial Clock Protein KaiA

Abstract

Regulation of daily physiological functions with a ~24-hour periodicity, or circadian rhythms, exists in both eukaryotes and prokaryotes. So far, cyanobacteria are only known prokaryotes proved to have circadian rhythmicity. The circadian system in cyanobacteria comprises a post-translational oscillator (PTO) and a transcriptional/translational feedback loop (TTFL). The PTO comprise of three proteins (KaiA, KaiB, KaiC), and can be reconstituted in vitro with the existence of ATP. Phase of the PTO is associated with the phosphorylation states of KaiC, with KaiA promoting the phosphorylation of KaiC, and KaiB promoting the de-phosphorylation. Here we studied the dynamics of the KaiA protein ofThermosynechococcus elongatus. The result will be helpful in understanding the function of KaiA and its binding with KaiC.