Ligand channel in pharmacologically stabilized rhodopsin

Area of Science:

• Biochemistry
• Structural Biology
• Ophthalmology

Background:

• Retinitis pigmentosa (RP) is a degenerative eye disease caused by protein misfolding, affecting cell metabolism and photoreceptor survival.
• Current therapeutic strategies for RP aim to stabilize mutant rhodopsin (a G protein-coupled receptor) using pharmacological chaperones (PC) to improve folding and trafficking.

Purpose of the Study:

• To identify novel small molecules that stabilize rhodopsin mutants.
• To elucidate the structural basis of rhodopsin stabilization by small molecules.

Main Methods:

• Virtual screening and thermofluor screening were employed to discover stabilizing small molecules.
• Crystal structure determination of stabilized opsin (using hit S-RS1) at 2.4 Å resolution.
• Chemical modification of a lead compound (S-RS1) and subsequent structural analysis.

Main Results:

• Discovery of nonretinal small molecules that stabilize rhodopsin.
• Determination of the crystal structure revealing the binding motif of stabilizers at the orthosteric site.
• Identification of novel conformational changes in rhodopsin, including an open channel facilitating ligand exchange.

Conclusions:

• The identified small molecules represent a promising therapeutic approach for rhodopsin-related retinitis pigmentosa.
• Understanding rhodopsin's conformational flexibility is crucial for developing effective treatments.
• This work provides a foundation for drug intervention against RP by stabilizing rhodopsin.