Proteomics of early and late cold shock stress on thermophilic bacterium, Thermus sp. GH5

Thermus sp. GH5 is an aerobic thermophilic bacterium with optimal growth at 70-75°C isolated from a hot spring in Ardabil, North West province of Iran. Due to industrial and biotechnological applications of thermophils, it is very important to know more about their proteomes and metabolomes. Since thermophils live in stressful environments it will be very useful to study their survival mechanisms. There are many reports on stress induced proteins, particularly the well characterized heat shock proteins, but little is known about the functions of proteins induced after a decrease in temperature. In this study, the proteomes of the thermophilic bacterium after a temperature down shift from 75°C to 45°C for 2h and 5h were investigated. We also compared protein profiles of early and late cold shock processes to that of cells grown at 75°C and identified a set of proteins, some of which are involved in metabolic processes such as fatty acid synthesis, pentose phosphate pathway, aromatic component degradation and signal transduction. Our data showed this organism could be tolerating the stress conditions by changing its metabolism and physiology.