Details

Autor(en) / Beteiligte

• Furuike, Yoshihiko
• Ouyang, Dongyan
• Tominaga, Taiki
• Matsuo, Tatsuhito
• Mukaiyama, Atsushi
• Kawakita, Yukinobu
• Fujiwara, Satoru
• Akiyama, Shuji

Titel

Cross-scale analysis of temperature compensation in the cyanobacterial circadian clock system

Ist Teil von

• Communications physics, 2022-04, Vol.5 (1), p.1-12, Article 75

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2022

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Circadian clock proteins often reveal temperature-compensatory responses that counteract temperature influences to keep their enzymatic activities constant over a physiological range of temperature. This temperature-compensating ability at the reaction level is likely crucial for circadian clock systems, to which the clock proteins are incorporated, to achieve the system-level temperature compensation of the oscillation frequency. Nevertheless, temperature compensation is yet a puzzling phenomenon, since side chains that make up the clock proteins fluctuate more frequently due to greater thermal energy at higher temperature. Here, we investigated temperature influences on the dynamics of KaiC, a temperature-compensated enzyme (ATPase) that hydrolyzes ATP into ADP in the cyanobacterial circadian clock system, using quasielastic neutron scattering. The frequency of picosecond to sub-nanosecond incoherent local motions in KaiC was accelerated by a factor of only 1.2 by increasing the temperature by 10 °C. This temperature insensitivity of the local motions was not necessarily unique to KaiC, but confirmed also for a series of temperature-sensitive mutants of KaiC and proteins other than clock-related proteins. Rather, the dynamics associated with the temperature-compensatory nature of the reaction- and system-level was found in global diffusional motions, which was suggested to regulate the temperature dependence of ATPase activity and dephosphorylation process presumably through changes in the hexamer conformation of KaiC. The spatiotemporal scale at which cross-scale causality of the temperature sensitivity is established is finite, and extends down to picosecond to sub-nanosecond dynamics only in a very limited part of KaiC, not in its entire part. The mechanism by which circadian clock proteins compensate for changes in temperature to maintain regular operation remains unclear. Here, temperature compensation from the reaction to cell level is explained by large-scale motions inside the clock protein observed via neutron scattering spectroscopy.