biostudies-literatureWalunjkar NNIH HHSNIGMS NIH HHSmsaf137https://www.ebi.ac.uk/biostudies/studies/S-EPMC12227239biostudies-literatureUnknown42(7)Temperature is a universal environmental constraint and organisms have evolved diverse mechanisms of thermotolerance. A central feature of thermophiles relative to mesophiles is a universal shift in protein stability, implying that it is a major constituent of thermotolerance. However, organisms have also evolved extensive buffering systems, such as those that disaggregate and refold denatured proteins and enable survival of heat shock. Here, we show that both cellular and protein structural changes contribute to divergence in protein thermostability between two closely related Saccharomyces species that differ by 8 °C in their thermotolerance. Using thermal proteomic profiling we find that 85% of S. cerevisiae proteins are more stable than their S. uvarum homologs and there is a 1.6 °C shMolecular biology and evolutionPervasive Divergence in Protein Thermostability is Mediated by Both Structural Changes and Cellular Environments.PMC12227239GM080669GM052347OD025242R35 GM119502R01 GM080669S10 OD025242GM119502R01 GM052347Akhter NMarcus EMiller JHGhaemmaghami SLai TYFay JCBettinger JQWalunjkar NPhizicky EMfalsePervasive Divergence in Protein Thermostability is Mediated by Both Structural Changes and Cellular Environments.Temperature is a universal environmental constraint and organisms have evolved diverse mechanisms of thermotolerance. A central feature of thermophiles relative to mesophiles is a universal shift in protein stability, implying that it is a major constituent of thermotolerance. However, organisms have also evolved extensive buffering systems, such as those that disaggregate and refold denatured proteins and enable survival of heat shock. Here, we show that both cellular and protein structural changes contribute to divergence in protein thermostability between two closely related Saccharomyces species that differ by 8 °C in their thermotolerance. Using thermal proteomic profiling we find that 85% of S. cerevisiae proteins are more stable than their S. uvarum homologs and there is a 1.6 °C sh2025-01-01T00:00:00Z2025 Jul2025-08-14T03:05:48.771Z2025-08-14T03:05:48.771ZS-EPMC122272394047660510.1093/molbev/msaf137