Roles of cold-inducible chaperones in hyperthermophiles

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It has been suggested that hyperthermophiles are highly primitive microorganisms and that their descendents evolved by adapting to cooler environments. Hence, study of the adaptive mechanisms of hyperthermophiles to cold environments may provide insight into evolutionary processes. In the project, the physiological roles of cold inducible chaperones, cpkA (TK0678) and DEAD box RNA helicase (TK0306) from Thermococcus kodakarensis were investigated, showing that both genes are essential for cell growth at cold stressed environment. In addition, the region required for cold induction of TK0306 was identified. The regulatory element, a five-adenosine sequence has been located in the region between the SD region and the initiation codon (ATG). It seems likely that A5 -dependent cold-induced expression is related to premature termination depending on temperature. This sequence-specific mechanism is unique, and one that has not been identified in other known cold-inducible genes.