Beyond spectral tuning: Human cone visual pigments adopt different transient conformations for chromophore regeneration

Sundaramoorthy Srinivasan, Arnau Cordomí, Eva Ramon, Pere Garriga

Research output: Contribution to journalArticleResearchpeer-review

6 Citations (Scopus)

Abstract

© 2015 Springer Basel. Human red and green visual pigments are seven transmembrane receptors of cone photoreceptor cells of the retina that mediate color vision. These pigments share a very high degree of homology and have been assumed to feature analogous structural and functional properties. We report on a different regeneration mechanism among red and green cone opsins with retinal analogs using UV-Vis/fluorescence spectroscopic analyses, molecular modeling and site-directed mutagenesis. We find that photoactivated green cone opsin adopts a transient conformation which regenerates via an unprotonated Schiff base linkage with its natural chromophore, whereas red cone opsin forms a typical protonated Schiff base. The chromophore regeneration kinetics is consistent with a secondary retinal uptake by the cone pigments. Overall, our findings reveal, for the first time, structural differences in the photoactivated conformation between red and green cone pigments that may be linked to their molecular evolution, and support the proposal of secondary retinal binding to visual pigments, in addition to binding to the canonical primary site, which may serve as a regulatory mechanism of dark adaptation in the phototransduction process.
Original languageEnglish
Pages (from-to)1253-1263
JournalCellular and Molecular Life Sciences
Volume73
Issue number6
DOIs
Publication statusPublished - 1 Mar 2016

Keywords

  • Color vision
  • G-protein coupled receptors
  • Ligand binding
  • Retinal
  • Visual phototransduction

Fingerprint Dive into the research topics of 'Beyond spectral tuning: Human cone visual pigments adopt different transient conformations for chromophore regeneration'. Together they form a unique fingerprint.

Cite this