Uncovering Mechanisms for Repair and Protection in Cold Environments Through Studies of Cold Adapted Archaea

摘要

Methanococcoides burtonii is a cold-adapted archaeon isolated from permanently cold (1-2 deg C), methane saturated waters in Ace Lake, Antarctica. M. burtonii is a motile, flagellated microbe that uses methylated carbon compounds for growth (methylotrophy), such as methanol and trimethylamine. Although adapted to the cold, M. burtonii is capable of growth at much higher temperatures, with the highest (= optimal) growth rate occurring at 23 deg C, and a maximum growth temperature of 28 deg C. We have employed two separate but integrated approaches for investigating the basis of cold adaptation in M. burtonii: targeted protein studies, and global proteomic analysis. Our first approach focuses on the study of the chaperonin (Cpn60) complex, which is important for the correct folding of proteins inside the cell. Our second approach aims to determine how protein expression changes in the entire cell at different growth temperatures, using isotope labeling of proteins and liquid chromatography-tandem mass spectrometry (LC/LC-MS/MS). Our research aims to provide fundamental knowledge about the molecular mechanisms of adaptation to growth at cold temperatures in archaea. This will enable us to identify molecular strategies that have evolved in order to cope with extreme cold, with the cell in a state of permanent cold stress. This is interesting in terms of both the limits of archaeal adaptation to low temperature extremes, and in considering whether archaeal mechanisms for cold adaptation may be extended to other systems.