Protein Folding at Extreme Temperatures: Current Issues

Abstract

The range of temperatures compatible with life is currently estimated from −20°C, as exemplified by metabolically active bacteria between sea ice crystals, and up to 122°C in hydrothermal vents as exemplified by the archaeon Methanopyrus kandleri. Microbial life under these extreme environmental temperatures obviously requires a vast array of adaptations at all cellular levels. In the context of protein folding, as soon as a polypeptide emerges from the ribosome, it is exposed to the effects of the environmental temperatures. Recent investigations have addressed some essential questions: i) what is the effect of extreme environmental temperatures on the protein folding rate; ii) how do PPIases catalyze prolyl isomerization, a rate-limiting step in protein folding; iii) the “trigger factor” is the first chaperone interacting with nascent chains: how does it help protein folding at extreme temperatures and iv) what are the properties of the final native state of proteins adapted to these temperatures? The available results that will be summarized here open new perspectives for the study of life in extreme environments.