Equilibrium Binding of Wild-type and Mutant Drosophila Heat Shock Factor DNA Binding Domain with HSE DNA Studied by Analytical Ultracentrifugation

Abstract

We have investigated binding between wild-type and mutant Heat Shock Factor (HSF) DNA binding domains (DBDs) with 17-bp HSE containing a central 5'-NGAAN-3' element by equilibrium analytical ultracentrifugation using multi-wavelength technique. Our results indicate that R102 plays critical role in HSE recognition and the interactions are characterized by substantial negative changes of enthalpy () and entropy () with free energy change, of . N105 plays minor role in the HSE interactions with of , of and of , which are similar to those observed for wild-type DBD:HSE interactions (, and ) indicating higher entropy contribution for both wild-type and N105A DBD bindings to the HSE.