Microgravity crystallization of cjFP510, a hyperstable fluorescent protein derived from a deep-sea anemone

Abstract Background: cjFP510 is a hyperstable fluorescent protein derived from the deep-sea anemone Cribrinopsis japonica. The unique pressure-resistant nature of such proteins makes them promising candidates for crystallization under microgravity. Methods: We utilized the JAXA PCG framework to evaluate crystallization of cjFP510 aboard the ISS. Crystals were grown using counter-diffusion methods, and post-flight analysis was performed at SPring-8. Results: Crystals diffracted to a resolution of ~2.0 Å. The structure confirms cjFP510's integrity in space and supports its robustness as a fluorescent marker. Conclusions: This study demonstrates that deep-sea-derived proteins can maintain stability and crystallize in space. cjFP510 represents a promising tool for advanced imaging and structural applications in biomedical research. This is the first report of space-based crystallization of a fluorescent protein derived from a deep-sea organism.