Molecular determinant modulates thermal recovery kinetics and structural integrity of the bacterial BLUF photoreceptor

BLUF domains are flavin-based photoreceptors which receive the blue light signal and are involved in the sensory transduction. We report a short BLUF photoreceptor (SnfB) in Stenotrophomonas sp. We have investigated photodynamic properties of C terminus truncated and several mutated SnfB proteins. Deletion of the extended C-terminal residues alters the thermal recovery kinetics and also affects the integrity of the SnfB protein. Mutagenesis studies demonstrated that the conserved residues within and outside the flavin-binding pocket also regulates the photocycle properties of the protein. These studies suggest that the C-terminal residues outside the BLUF domain can tune the photodynamic properties of the BLUF protein.