Measuring the confinement effect on p53 stability using reverse micelles.

P53, the main tumor suppressor of the human body consists of five domains. Roughly 50-60% of cancers include a mutation of the P53 gene, 90% of which are found in the core DNA-binding domain. It is now well established that these mutations induce altered stability of the DNA-binding domain, thereby resulting in dysfunction. The wealth of data on p53 stability has been generated in bulk aqueous solution, but p53 is natively found in the nucleus of the cell which is a highly confined environment. Confinement is generally predicted to result in an entropic stabilization of the native state, leading us to ask if p53 stability, which is so vital to function, would be impacted by confinement. Here, we use reverse micelles (RMs), spontaneously organizing nanobubbles, to create such a condition. RMs consisting of surfactants decylmonoacyl glycerol (10MAG) and lauryldimethylamino-N-oxide (LDAO) have been shown to encapsulate proteins while preserving their native state. Here, we investigate the stability of the wild-type p53 core domain to thermal denaturation under equilibrium and non-equilibrium conditions using intrinsic fluorescence and circular dichroism. We find that the RM condition does impact the overall stability of the protein and establish the foundation needed for investigating mutation effects on stability of the core domain.