Scientists have made the incredible discovery that the Earth's daily 24-hour rotation period is encoded in the KaiC protein at the atomic level.
This protein is expressed in cyanobacterial cells, and the finding could help researchers solve the mystery of how the circadian period of biological clocks is determined, the National Institutes of Natural Sciences reported.
Many organisms regulate their biological activities using this mysterious internal clock, but scientists are largely unsure of how it works. To gain insight into the phenomenon, researchers reconstructed the circadian clock in cyanobacteria by mixing the proteins KaiA, KaiB, and KaiC with ATP. KaiC ATPase activity was observed to exhibit and oscillating component even when KaiA and KaiB were absent. The researchers found this had a frequency of 0.91 day-1, which coincides with the Earth's 24-hour rotation period. This suggests KaiC is the source of biological functions that are linked with the rotation of the planet.
The study provides the first atomic-level demonstration that protein molecules are capable of creating 4-hour rhythms by regulating molecular structure and reactivity.
"The fact that a water molecule, ATP, the polypeptide chain, and other universal biological components are involved in this regulation suggests that humans and other complex organisms may also share a similar molecular machinery. In the crowded intracellular environment that contains a myriad of molecular signals, KaiC demonstrates long-paced oscillations using a small amount of energy generated through ATP consumption. This clever mechanism for timekeeping in a noisy environment may inspire development of highly efficient and sustainable chemical reaction processes and molecular-system-based information processing," said Lab head and CIMoS Director Professor Shuji Akiyama.
The findings were published in a recent edition of the journal Science Express.
