SYNTHESIS AND CHARACTERIZATION OF A NOVEL RETINYLAMINE ANALOG INHIBITOR OF CONSTITUTIVELY ACTIVE RHODOPSIN MUTANTS FOUND IN PATIENTS WITH AUTOSOMAL-DOMINANT RETINITIS-PIGMENTOSA

Two different mutations of the active-site Lys-296 in rhodopsin, K296E and K296M, have been found to cause autosomal dominant retinitis pigm entosa (ADRP). In vitro studies have shown that both mutations result in constitutive activation of the protein, suggesting that the activat ed state of the receptor may be responsible for retinal degeneration i n patients with these mutations. Previous work has highlighted the pot ential of retinylamine analogs as active-site directed inactivators of constitutively active mutants of rhodopsin with the idea that these o r related compounds might be used therapeutically for cases of ADRP in volving mutations of the active-site Lys. Unfortunately, however, amin e derivatives of 11-cis-retinal, although highly effective against a K 296G mutant of rhodopsin, were without affect on the two naturally occ urring ADRP mutants, presumably because of the greater steric bulk of Glu and Met side chains in comparison to Gly. For this reason we synth esized a retinylamine analog one carbon shorter than the parent 11-cis -retinal and show that this compound is indeed an effective inhibitor of both the K296E and K296M mutants. The 11-cis C19 retinylamine analo g 1 inhibits constitutive activation of transducin by these mutants an d their constitutive phosphorylation by rhodopsin kinase, and it does so in the presence of continuous illumination from room lights.