Acquired Thermotolerance and Temperature-Induced Protein Accumulation in the Extremely Thermophilic Bacterium Rhodothermus obamensis

Abstract

Temperature-induced changes in thermotolerance and protein composition were examined in heat-shocked cells and high-temperature-grown cells of the extremely thermophilic bacteriumRhodothermus obamensis. The survival at temperatures superoptimal for growth (90 and 95°C) was enhanced in both heat-shocked cells and high-temperature-grown cells relative to that of cells grown at optimal temperatures. In a comparison of protein composition using two-dimensional gel electrophoresis, putative heat shock proteins (HSPs) and high-temperature growth-specific proteins (HGPs) were detected. N-terminal amino acid sequence analysis revealed that the putative HSPs were quite similar to the ATP-binding subunits of ABC transporters and the HGPs were proteins corresponding to domains II and III of elongation factor Tu. These results suggested that this extreme thermophile has developed temperature-induced responses that include increased survival under hyperthermal conditions, changes in protein composition, and also the production of novel HSPs.

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