Hidden conformations differentiate day and night in a circadian pacemaker
biorxiv(2021)
摘要
The AAA+ protein KaiC is the central pacemaker for cyanobacterial circadian rhythms. Composed of two hexameric rings with tightly coupled activities, KaiC undergoes changes in autophosphorylation on its C-terminal (CII) domain that restrict binding of of clock proteins on its N-terminal (CI) domain to the evening. Here, we use cryo-electron microscopy to investigate how daytime and nighttime states of CII regulate KaiB binding to CI. We find that the CII hexamer is destabilized during the day but takes on a rigidified C2-symmetric state at night,concomitant with ring-ring compression. Residues at the CI-CII interface are required for phospho-dependent KaiB association, coupling ATPase activity on CI to cooperative KaiB recruitment. Together these studies reveal how daily changes in KaiC phosphorylation regulate cyanobacterial circadian rhythms.
One-Sentence Summary Cryo-EM structures of KaiC in its day and night states reveal the structural basis for assembly of clock regulatory complexes.
### Competing Interest Statement
The authors have declared no competing interest.
更多查看译文
关键词
night,conformations,day
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要