Jobim 2008

Thermophilic organisms require proteins that maintain their structure and activity in the extreme temperature conditions in which their hosts thrive. In view of evaluating the influence of temperature on the different types of interactions that stabilize protein structures, we developed a new approach based on temperature-dependent mean force potentials. Our results show that the stabilizing weight of hydrophobic interactions remains constant, relatively to the other interactions, as the temperature increases. In contrast, Arg-involving salt bridges were found to be significantly more stabilizing at high temperature. A preference for more compact salt bridge geometries is moreover noticeable in heat-resistant proteins. Since the melting temperatures of proteins (Tm) are frequently estimated on the basis of the living temperatures (Tenv) of their host organisms, we also investigated the relationship between these two quantities, to assess the relevance of such an approximation in the context of protein thermostability analyzes.