Thursday, 27th June, 2013, 11:00-12:00

Visual phototransduction: from rhodopsin mutations to retinal disease

Rhodopsin is the visual pigment of the vertebrate retina responsible for light capture in the first molecular events of the complex process of vision. This photoreceptor protein has served as a prototypical model for G-protein coupled receptors (GPCRs) superfamily. Upon photoactivation, rhodopsin binds and activates the specific G- protein transducin. The details of this light-dependent activation, including the molecular interaction with transducin, have not been fully elucidated. Mutations in rhodopsin have been associated with the retinal degenerative disease retinitis pigmentosa (RP). The folding, degradation and aggregation of some of these mutant rhodopsins can be manipulated by drugs or molecular chaperones. Our goal is to deepen our knowledge of the molecular consequences of such mutations while gaining, at the same time, new insights into the structural requirements of the photoactivation process. We are also interested in the effect of lipids and metal ions on the structure, stability and function of rhodopsin, and the ligand protein interactions comparison between rhodopsin and cone opsin pigments. We will describe recent results on rhodopsin mutations associated to RP or potentially relevant for visual pigment evolution, the effect of docosohexaenoic acid lipid on the stability of purified rhodopsin and the kinetic differences between rhodopsin and red cone opsin ligand binding after photoactivation. Overall, our studies may enhance our understanding of the molecular mechanisms of phototransduction, the biology of GPCRs in general, and importantly, they may help develop potential approaches to treat RP caused by rhodopsin mutations.

(Supported by grants SAF2011-30216-C02-01 from MICINN, CIVP16A1861 from Fundación Ramón Areces, and Grups de Recerca Consolidats de la Generalitat de Catalunya (2009 SGR 1402).

Speaker: Pere Garriga, Department of Chemical Engineering, Universitat Politècnica de Catalunya (UPC)

Room Xipre (seminar 173.06-183.01), PRBB.