Title
Mechanistic basis of the fast dark recovery of the short LOV protein DsLOV from Dinoroseobacter shibae
Author
Timo Fettweiss, Katrin Röllen, Joachim Granzin, Oliver Reiners, Stephan Endres, Thomas Drepper, Dieter Willbold, Karl-Erich Jaeger, Renu Batra-Safferling, Ulrich Krauss
Year
2018
Journal
Biochemistry
Abstract
Light, oxygen, voltage (LOV) proteins, a ubiquitously distributed class of photoreceptors, regulate a wide variety of light-dependent physiological responses. Due to their modular architecture, LOV domains, i.e. the sensory domains of LOV photoreceptors, have been widely used for the construction of optogenetic tools. We recently described the structure and function of a short LOV protein (DsLOV) from the marine phototropic bacterium Dinoroseobacter shibae, for which, in contrast to other LOV photoreceptors, the dark state represents the physiologically relevant signaling state. Among bacterial LOV photoreceptors, DsLOV possesses an exceptionally fast dark recovery, corroborating its function as “dark” sensor. To address the mechanistic basis of this unusual characteristic, we carried out a comprehensive mutational, kinetic, thermodynamic and structural characterization of DsLOV. The mechanistic basis of the fast dark recovery of the protein was revealed by mutation of the previously noted uncommon residue substitution at position 49 found in DsLOV. The substitution of M49 by different residues that are naturally conserved in LOV domains tuned the dark recovery time of DsLOV over three orders of magnitude, without grossly affecting its overall structure or light-dependent structural change observed for the wild-type protein. Our study thus provides a striking example of how nature can achieve LOV photocycle tuning by subtle structural alterations in the LOV domain active site, highlighting the easy evolutionary adaptability of the light sensory function. At the same time, our data provides guidance for the mutational photocycle tuning of LOV domains, with relevance for the growing field of optogenetics.
Instrument
J-810
Keywords
Circular dichroism, Secondary structure, Chemical stability, Kinetics, Biochemistry