Can Osmolytes TMAO and Glycerol Rescue Destabilized Temperature-Sensitive Mutants of P53?

Abstract

Some 30-40% of oncogenic mutants of p53 are inactive because of low stability. Stabilization of such mutants is one route for novel anti-cancer drugs. The osmolytes glycerol and trimethylamine N-oxide stabilize all proteins by a combination of effects on solvent water and by direct interactions with proteins. It has been reported that protein instability defects in temperature-sensitive p53 mutants can be rescued in cell lines by the addition of low concentrations of those compounds. We measured the effects of glycerol and trimethylamine N-oxide on the thermal and kinetic stability of wild-type p53 and temperaturesensitive mutants in vitro and found that there were just negligible increases in stability at the concentrations reportedly used in cell lines. We found no rescue of mutants in H1299 cell lines at those reported concentrations. There was some stabilization at higher concentrations of glycerol and trimethylamine N-oxide in vitro but these concentrations were toxic to the cells. It would seem unlikely that the use of general osmloytes would be an effective strategy for the rescue of unstable mutants because even if they were effective at stabilizing p53, they would alter the proteostasis of the cell.