Cyanobacteria use light to survive, and these organisms are regulated by circadian rhythms–the 24-hour biological cycle that is found in many animals, and which helps control fundamental processes like metabolism and the sleep-wake cycle.Researchers studying these microbes have now determined that artificial cells made to model cyanobacteria can keep accurate time, just like circadian rhythms.
In this work, scientists investigated the circadian clock in cyanobacteria by isolating proteins that are crucial to the cycle, and studying them in structures called vesicles. One of these microbial proteins was also marked with a fluorescent tag.
These models, or artificial cells, glowed rhythmically for four days or more, but if there was a reduction in the number of proteins, or the vesicles were too small, the glow stopped. The rhythmic glowing can be seen in the video below.
With a computational analysis, the researchers determined that higher concentrations of proteins related to the circadian rhythm would make the clock more robust, and thousands of vesicles could keep time.
The study, which was reported in Nature Communications, also suggested that gene activity is not always directly related to maintaining clocks in individual cells, but is instead involved in coordinating timing in a population of cells.
"This study shows that we can dissect and understand the core principles of biological timekeeping using simplified, synthetic systems," noted senior study author Professor Anand Bala Subramaniam of the University of California, Merced.
"The cyanobacterial circadian clock relies on slow biochemical reactions that are inherently noisy, and it has been proposed that high clock protein numbers are needed to buffer this noise," noted Mingxu Fang, a microbiology professor at Ohio State University and circadian rhythm expert.
"This new study introduces a method to observe reconstituted clock reactions within size-adjustable vesicles that mimic cellular dimensions. This powerful tool enables direct testing of how and why organisms with different cell sizes may adopt distinct timing strategies, thereby deepening our understanding of biological timekeeping mechanisms across lifeforms."
Sources: University of California - Merced, Nature Communications
