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Chromophore Exchange in the Blue Light‐Sensitive Photoreceptor YtvA from Bacillus subtilis
Author(s) -
Mansurova Madina,
Scheercousse Pierre,
Simon Julian,
Kluth Marianne,
Gärtner Wolfgang
Publication year - 2011
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201000515
Subject(s) - flavin mononucleotide , chromophore , flavin group , chemistry , photochemistry , quantum yield , flavoprotein , phytochrome , fluorescence , biochemistry , biology , physics , quantum mechanics , enzyme , red light , botany
Abstract YtvA from Bacillus subtilis was found as the first prokaryotic phototropin‐like blue‐light‐responsive photoreceptor. It is composed of two domains, the photoactive LOV (light, oxygen, voltage) domain, which binds a flavin mononucleotide (FMN) as a chromophore and a STAS (sulfate transporter/anti‐sigma‐factor antagonist) domain, which generates a physiological signal. Here we present a routine chromophore‐exchange protocol that allows chemically synthesized, structurally modified chromophores instead of the naturally present flavin mononucleotide (FMN) chromophore to be introduced. FMN was exchanged for riboflavin (RF), flavin adenine dinucleotide (FAD), 7,8‐didemethyl flavin mononucleotide (DMFMN), and 8‐isopropyl flavin mononucleotide ( ipr FMN). LOV domains reconstituted with new flavins undergo the same photocycle as native YtvA LOV, consisting of triplet formation and covalent binding of the chromophore followed by a thermal recovery of the parent state, albeit with different kinetics and photophysical properties. Interestingly, the ipr FMN chromophore, inducing steric hindrances to the protein, exhibits a very fast light‐to‐dark‐conversion and shows a high fluorescence quantum yield (0.4). Incorporation of FAD causes an increase of its fluorescence quantum yield from 0.04 (H 2 O) to 0.2.