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PDBsum entry 4hj3
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Signaling protein
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PDB id
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4hj3
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References listed in PDB file
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Key reference
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Title
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Light-Induced subunit dissociation by a light-Oxygen-Voltage domain photoreceptor from rhodobacter sphaeroides.
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Authors
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K.S.Conrad,
A.M.Bilwes,
B.R.Crane.
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Ref.
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Biochemistry, 2013,
52,
378-391.
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PubMed id
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Abstract
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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.
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