A proteomic approach toward the selection of proteins with enhanced intrinsic conformational stability

Journal of Proteome Research (2006)5: 2720-2726

A detailed understanding of the molecular basis of protein folding and stability determinants partly relies on the study of proteins with enhanced conformational stability properties, such as those from thermophilic organisms. In this study we set up a methodology aiming at identifying the subset of cytosolic hyperstable proteins using Sulfurispharea sp., a hyperthermophilic archaeon, able to grow between 70-97°C, as a model organism. We have thermally and chemically perturbed the cytosolic proteome as a function of time (up to 96h incubation at 90°C), and proceeded with analysis of the remaining proteins by combining one and two dimensional gel electrophoresis, liquid chromatography fractionation, and protein identification by N-terminal sequencing and mass spectrometry methods. A total of 14 proteins with enhanced stabilities which are involved in key cellular processes such as detoxification, nucleic acid processing and energy metabolism were identified including a superoxide dismutase, a peroxiredoxin and a ferredoxin. We demonstrate that these proteins are biologically active after extensive thermal treatment of the proteome. The relevance of these and other targets is discussed in terms of the organism’s ecology. This work thus illustrates an experimental approach aimed at mining a proteome for hyperstable proteins, a valuable tool for target selection in protein stability and structural studies.