Allosteric effects in the marginally stable von Hippel-Lindau tumor suppressor protein and allostery-based rescue mutant design.

Abstract

Many multifunctional tumor suppressor proteins have low stability, a property linked to cancer development. The von Hippel-Lindau tumor suppressor protein (pVHL) is one of these proteins. pVHL forms part of the E3 ubiquitin ligase complex that regulates the degradation of the hypoxia-inducible factor (HIF). Under native conditions, free pVHL is a molten globule, but it is stabilized in the E3 complex. By using molecular dynamics simulations, we observed that the interface between the two pVHL domains is the least stable region in unbound pVHL. We designed five stable mutants: one with a mutation at the interdomain interface and the others in the alpha- or beta-domains. Experimentally, type 2B pVHL disease mutant Y98N at the HIF binding site was shown to destabilize pVHL and decrease its binding affinity to HIF. Our simulations showed that the decrease in pVHL stability and binding affinity are allosterically regulated. The mutations designed to stabilize unbound wild-type pVHL, which are away from the elongin C and HIF binding sites, successfully stabilized the Y98N pVHL-elongin C complex and lowered the binding free energy of pVHL with HIF. Our results indicated both the enthalpic and dynamic allosteric components between the elongin C and HIF binding sites in pVHL, in the alpha- and beta-domains, respectively, mediated by the interdomain interface and linker. Drugs mimicking the allosteric effects of these mutants may rescue pVHL function in von Hippel-Lindau disease.