3D72

Light activation of the LOV protein vivid generates a rapidly exchanging dimer.

(2008) Biochemistry 47: 7012-7019

• PubMed: 18553928 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1021/bi8007017
• Primary Citation of Related Structures:  
  3D72


• PubMed Abstract: 
  

  The fungal photoreceptor Vivid (VVD) plays an important role in the adaptation of blue-light responses in Neurospora crassa. VVD, an FAD-binding LOV (light, oxygen, voltage) protein, couples light-induced cysteinyl adduct formation at the flavin ring to conformational changes in the N-terminal cap (Ncap) of the VVD PAS domain. Size-exclusion chromatography (SEC), equilibrium ultracentrifugation, and static and dynamic light scattering show that these conformational changes generate a rapidly exchanging VVD dimer, with an expanded hydrodynamic radius. A three-residue N-terminal beta-turn that assumes two different conformations in a crystal structure of a VVD C71V variant is essential for light-state dimerization. Residue substitutions at a critical hinge between the Ncap and PAS core can inhibit or enhance dimerization, whereas a Tyr to Trp substitution at the Ncap-PAS interface stabilizes the light-state dimer. Cross-linking through engineered disulfides indicates that the light-state dimer differs considerably from the dark-state dimer found in VVD crystal structures. These results verify the role of Ncap conformational changes in gating the photic response of N. crassa and indicate that LOV-LOV homo- or heterodimerization may be a mechanism for regulating light-activated gene expression.

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Organizational Affiliation: 

Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.