Researchers have gained new insights into how the light-sensitive part of the biomolecule phytochrome transitions from a light-adapted to a dark-adapted state using various spectroscopic methods. They discovered that cyanobacterial and plant phytochromes could convert red and far-red light stimulation into mechanical output. Their discovery has the potential to be used as an optogenetic tool.
The researchers used a special type of mass spectrometry and electron spin resonance spectrometry to examine a phytochrome molecule from cyanobacteria. Using these methods, they could study the molecule in solution and track its structural changes without crystallizing it. They discovered several distinct structural changes in the phytochrome’s light-sensitive segment and developed a model that depicted the light-triggered conversion steps. Furthermore, the team demonstrated a universal mechanism for transitioning from the dark-adapted to the light-adapted state for different phytochromes.
At the moment, only a few light-sensitive biomolecule structures are known. Our understanding of them extends only to their final states in light and darkness, not to their intermediate states.
Understanding how photoreceptors in biomolecules change their spatial structure when exposed to light could lead to advances in biophotonics and other fields.
Light-sensitive biomolecules, such as phytochromes from plants, are interesting for various applications, including agriculture, where a change in phytochrome could optimize plant growth habits, and optogenetic tools, which allow light to control the activity of genetically modified cells in the living body.