ja2c02054_si_001.pdf (1.97 MB)
Download fileThe Magic of Linking Rings: Discovery of a Unique Photoinduced Fluorescent Protein Crosslink
journal contribution
posted on 2022-05-14, 12:03 authored by Manman Lu, Dmitri Toptygin, Yufei Xiang, Yi Shi, Charles D. Schwieters, Emma C. Lipinski, Jinwoo Ahn, In-Ja L. Byeon, Angela M. GronenbornFluorosubstituted tryptophans serve
as valuable probes for fluorescence
and nuclear magnetic resonance (NMR) studies of proteins. Here, we
describe an unusual photoreactivity introduced by replacing the single
tryptophan in cyclophilin A with 7-fluoro-tryptophan. UV exposure
at 282 nm defluorinates 7-fluoro-tryptophan and crosslinks it to a
nearby phenylalanine, generating a bright fluorophore. The crosslink-containing
fluorescent protein possesses a large quantum yield of ∼0.40
with a fluorescence lifetime of 2.38 ns. The chemical nature of the
crosslink and the three-dimensional protein structure were determined
by mass spectrometry and NMR spectroscopy. To the best of our knowledge,
this is the first report of a Phe–Trp crosslink in a protein.
Our finding may break new ground for developing novel fluorescence
probes and for devising new strategies to exploit aromatic crosslinks
in proteins.