Light-induced subunit dissociation by a light-oxygen-voltage domain photoreceptor from Rhodobacter sphaeroides.Conrad, K.S., Bilwes, A.M., Crane, B.R.
(2013) Biochemistry 52: 378-391
- PubMed: 23252338
- DOI: 10.1021/bi3015373
- Primary Citation of Related Structures:  4HJ3, 4HJ4, 4HJ6, 4HNB
- PubMed Abstract:
Light-oxygen-voltage (LOV) domains bind a flavin chromophore to serve as blue light sensors in a wide range of eukaryotic and prokaryotic proteins. LOV domains are associated with a variable effector domain or a separate protein signaling partner to ...
Light-oxygen-voltage (LOV) domains bind a flavin chromophore to serve as blue light sensors in a wide range of eukaryotic and prokaryotic proteins. LOV domains are associated with a variable effector domain or a separate protein signaling partner to execute a wide variety of functions that include regulation of kinases, generation of anti-sigma factor antagonists, and regulation of circadian clocks. Here we present the crystal structure, photocycle kinetics, association properties, and spectroscopic features of a full-length LOV domain protein from Rhodobacter sphaeroides (RsLOV). RsLOV exhibits N- and C-terminal helical extensions that form an unusual helical bundle at its dimer interface with some resemblance to the helical transducer of sensory rhodopsin II. The blue light-induced conformational changes of RsLOV revealed from a comparison of light- and dark-state crystal structures support a shared signaling mechanism of LOV domain proteins that originates with the light-induced formation of a flavin-cysteinyl photoadduct. Adduct formation disrupts hydrogen bonding in the active site and propagates structural changes through the LOV domain core to the N- and C-terminal extensions. Single-residue variants in the active site and dimer interface of RsLOV alter photoadduct lifetimes and induce structural changes that perturb the oligomeric state. Size exclusion chromatography, multiangle light scattering, small-angle X-ray scattering, and cross-linking studies indicate that RsLOV dimerizes in the dark but, upon light excitation, dissociates into monomers. This light-induced switch in oligomeric state may prove to be useful for engineering molecular associations in controlled cellular settings.
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.