Oxygen-induced chromophore degradation in the photoswitchable red fluorescent protein rsCherry

• Published in: International journal of biological macromolecules 2023-06, Vol.239, p.124179-124179, Article 124179
• Main Authors: Bui, Thi Yen Hang, De Zitter, Elke, Moeyaert, Benjamien, Pecqueur, Ludovic, Srinivasu, Bindu Y., Economou, Anastassios, Fontecave, Marc, Van Meervelt, Luc, Dedecker, Peter, Pedre, Brandán
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Chromophore degradation; Crystal structure; Crystallography, X-Ray; Green Fluorescent Proteins - chemistry; Luminescent Proteins - chemistry; Models, Molecular; Oxygen; Protein Conformation; Red Fluorescent Protein
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2023.124179

Reversibly switchable monomeric Cherry (rsCherry) is a photoswitchable variant of the red fluorescent protein mCherry. We report that this protein gradually and irreversibly loses its red fluorescence in the dark over a period of months at 4 °C and a few days at 37 °C. We also find that its ancestor, mCherry, undergoes a similar fluorescence loss but at a slower rate. X-ray crystallography and mass spectrometry reveal that this is caused by the cleavage of the p-hydroxyphenyl ring from the chromophore and the formation of two novel types of cyclic structures at the remaining chromophore moiety. Overall, our work sheds light on a new process occurring within fluorescent proteins, further adding to the chemical diversity and versatility of these molecules.