Real-Time Tracking of Proton Transfer from the Reactive Cysteine to the Flavin Chromophore of a Photosensing Light Oxygen Voltage Protein.
Raiza N A MaiaDavid EhrenbergSabine OldemeyerEsther Knieps-GrünhagenUlrich KraussJoachim HeberlePublished in: Journal of the American Chemical Society (2021)
LOV (light oxygen voltage) proteins are photosensors ubiquitous to all domains of life. A variant of the short LOV protein from Dinoroseobacter shibae (DsLOV) exhibits an exceptionally fast photocycle. We performed time-resolved molecular spectroscopy on DsLOV-M49S and characterized the formation of the thio-adduct state with a covalent bond between the reactive cysteine (C72) and C4a of the FMN. By use of a tunable quantum cascade laser, the weak absorption change of the vibrational band of S-H stretching vibration of C57 was resolved with a time resolution of 10 ns. Deprotonation of C72 proceeded with a time constant of 12 μs which tallies the rise of the thio-adduct state. These results provide valuable information for the mechanistic interpretation of light-induced structural changes in LOV domains, which involves the choreographed sequence of proton transfers, changes in electron density distributions, spin alterations of the latter, and transient bond formation and breakage. Such molecular insight will help develop new optogenetic tools based on flavin photoreceptors.
Keyphrases
- single molecule
- electron transfer
- living cells
- energy transfer
- density functional theory
- amino acid
- protein protein
- molecular dynamics
- transition metal
- high resolution
- binding protein
- high frequency
- molecular dynamics simulations
- healthcare
- dengue virus
- cerebral ischemia
- high speed
- subarachnoid hemorrhage
- social media
- blood brain barrier