AUTHOR=Krueger Taylor D. , Henderson J. Nathan , Breen Isabella L. , Zhu Liangdong , Wachter Rebekka M. , Mills Jeremy H. , Fang Chong TITLE=Capturing excited-state structural snapshots of evolutionary green-to-red photochromic fluorescent proteins JOURNAL=Frontiers in Chemistry VOLUME=11 YEAR=2023 URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1328081 DOI=10.3389/fchem.2023.1328081 ISSN=2296-2646 ABSTRACT=
Photochromic fluorescent proteins (FPs) have proved to be indispensable luminous probes for sophisticated and advanced bioimaging techniques. Among them, an interplay between photoswitching and photoconversion has only been observed in a limited subset of Kaede-like FPs that show potential for discovering the key mechanistic steps during green-to-red photoconversion. Various spectroscopic techniques including femtosecond stimulated Raman spectroscopy (FSRS), X-ray crystallography, and femtosecond transient absorption were employed on a set of five related FPs with varying photoconversion and photoswitching efficiencies. A 3-methyl-histidine chromophore derivative, incorporated through amber suppression using orthogonal aminoacyl tRNA synthetase/tRNA pairs, displays more dynamic photoswitching but greatly reduced photoconversion