Structural transition of the cyanobacterial clock protein KaiC in solution

2014 Fiscal Year Final Research Report

• Project/Area Number: 25840058
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Biophysics
• Research Institution: Institute for Molecular Science
• Principal Investigator: MUKAIYAMA Atsushi 分子科学研究所, 協奏分子システム研究センター, 助教 (80647446)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 生物時計 / タンパク質 / 構造変化

Outline of Final Research Achievements

Cyanobacterial circadian clock is composed of the three proteins, KaiA, KaiB, and KaiC. In this study, we examined the structural transition of KaiC during circadian oscillation. KaiC is a hexameric protein, consisting of the two rings. Recent studies have pointed out that ATPase of N-terminal ring of KaiC functions as a circadian pacemaker. We constructed KaiC mutant in which tryptophan (Trp) was introduced at the N-terimal ring and conducted time-resolved fluorescence measurements. We found that the fluorescence intensity from an inserted Trp exhibited the rhythmic change in the presence of KaiA and KaiB. This is a clear sign of the structural transition of the N-terminal ring in solution. The oscillatory amplitude in the fluorescence intensity was subtle, which indicates that small-scale structural transition of the N-terminal ring of KaiC.

Free Research Field

タンパク質科学