TitlePhenylalanine stacking enhances the red fluorescence of biliverdin IXα on UV excitation in sandercyanin fluorescent protein.
Publication TypeJournal Article
Year of Publication2022
AuthorsYadav K, Ghosh S, Barak A, Schaefer W, Subramanian R
JournalFEBS Lett
Date Published2022 Mar
KeywordsBiliverdine, Mutagenesis, Site-Directed, Phenylalanine, Proteins

Biliverdin IXα (BV) binds to several prokaryotic and eukaryotic proteins. How nature exploits the versatility of BV's properties is not fully understood. Unlike free BV, the Sandercyanin fluorescent protein bound to BV (SFP-BV) shows enhanced red fluorescence (675 nm) on excitation in the UV region (380 nm). Site-directed mutagenesis showed that the BV complex of two SFP variants, F55A and E79A, resulted in the loss of red fluorescence. Crystal structures of the complexes of these proteins with BV show the absence of stacking interactions of the F55 phenyl ring with BV. BV changes from ZZZssa conformation in the wild-type to ZZZsss conformation in the variants. In the nonfluorescent mutants, the lowest excited state is destabilized, resulting in nonradiative decay.

Alternate JournalFEBS Lett
PubMed ID35020202