Protein stability in extremophilic Archaea

Extremophilic microorganisms have adapted their molecular machinery to grow and thrive under the most adverse enviromental conditions. These microorga nisms have found their natural habitat at the boiling and freezing point of water, in high salt concentration and at extreme pH values. The extremophi lic proteins, selected by Nature to withstand this evolutionary pressure, r epresent a wide research field for scientists from different disciplines an d the study of the determinants of their stability has been an important ta sk for basic and applied research. A surprising conclusion emerges from the se studies: there are no general rules to achieve protein stabilization. Ea ch extremophilic protein adopts various strategies and the outstanding adap tation to extreme temperature and solvent conditions is realized through th e same weak electrostatic and hydrophobic interactions among the ordinary a mino acid residues which are also responsible for the proper balance betwee n protein stability and flexibility in mesophilic proteins.