| Microorganisms adapted to high temperature have evolved a variety of mechanisms to survive in this environment (thermoadaptation). Biochemical studies have provided a vast array of information on thermoadaptation. For this work, a comprehensive analysis of changes in gene expression patterns was performed for a 15°C temperature difference within the Arrhenius range of Geobacillus stearothermophilus NUB3621. No differentially expressed transcripts were isolated by subtractive cloning at the defined temperatures of 50°C and 65°C. Yet, two-dimensional liquid chromatography identified 27 proteins which are upregulated and 101 proteins which are downregulated at 65°C.; Protein H2, which is upregulated at 65°C, was sequenced and its corresponding gene cloned. This gene encodes 183 amino acids with a predicted molecular mass of 20.3 kDa and pI of 4.64. The protein sequence shares multiple characteristics with YkuU from B. subtilis. The amount of ykuU transcript in G. stearothermophilus NUB3621 was comparable at both 50°C and 65°C. With this protein as a model, it was concluded that some temperature regulated genes are controlled by a post-transcriptional mechanism.; A 15°C temperature difference within the Arrhenius range alters expression of a family of proteins in G. stearothermophilus NUB3621. The function of these proteins and their role in cell survival at increased temperatures remains unknown. These thermoadaptation studies we have initiated with G. stearothermophilus have opened up a rather novel area of gene regulation. These studies will contribute to our understanding of how this organism has adapted and serve as a paradigm for investigations with microorganisms that exist near the extremes of planetary conditions. This is a challenging frontier of current biology that will have wide spread interest in both the scientific and the biotechnology communities. |
