SPLIT: Stable Protein Coacervation Using a Light Induced Transition

Area of Science:

• Biochemistry
• Cell Biology
• Synthetic Biology

Background:

• Protein coacervates act as membraneless organelles, concentrating proteins and nucleotides to regulate cell physiology.
• The intrinsically disordered RGG domain of LAF-1 protein drives coacervation.
• Opto-responsive proteins can be used to control biological processes with light.

Purpose of the Study:

• To engineer a tunable, synthetic membraneless organelle that assembles in response to light.
• To develop a light-inducible system for protein phase separation.

Main Methods:

• Engineered a fusion protein comprising a solubilizing domain, the light-sensitive protein PhoCl, and the coacervation-driving RGG domain.
• Utilized 405 nm light to cleave PhoCl, triggering the removal of the solubilizing domain.
• Demonstrated coacervation in cellular-sized water-in-oil emulsions and in *Saccharomyces cerevisiae*.

Main Results:

• Cleavage of PhoCl by 405 nm light initiated RGG-driven coacervation within minutes.
• The engineered system showed light-induced coacervation in both in vitro emulsions and in yeast cells.
• Optimized system demonstrated efficient light-triggered assembly of synthetic membraneless organelles.

Conclusions:

• Developed a novel method for light-induced protein phase separation.
• Created tunable synthetic membraneless organelles with potential applications in cell biology and synthetic biology.
• The described strategies offer new tools for controlling cellular organization and function using light stimuli.