Freshwater ecosystems continue to reveal unexpected biological diversity and hidden molecular tools. Researchers have now identified HulaChrimson, a newly discovered channelrhodopsin found through freshwater metatranscriptomic sampling in Lake Hula, Israel. Channelrhodopsins are light sensitive proteins that can function as ion channels and have become essential tools in optogenetics, where light is used to control cellular activity.
What makes HulaChrimson particularly intriguing is its close similarity to Chrimson, one of the most widely used optogenetic proteins known for its red shifted light absorption. Despite sharing highly similar amino acid sequences, HulaChrimson behaved unexpectedly and displayed a substantially blue shifted response to light.
Researchers investigated whether individual amino acid differences could explain this striking contrast, but the results pointed toward a more complex mechanism. Rather than depending on only a few residues, colour tuning appears to be shaped by the broader architecture of the protein and its internal interaction network.
These findings not only deepen our understanding of how light sensing proteins function. They may also support the development of improved optogenetic tools for future applications in neuroscience and biotechnology.
The research was carried out with contributions from researchers at our project partner, the Technion – Israel Institute of Technology in Haifa, Israel, who were involved in the discovery and characterisation of HulaChrimson.