Cold shock proteins (CSPs) form a family of highly conserved bacterial proteins capable of single-stranded nucleic acid binding. They are suggested to act as RNA chaperones during cold shock inhibiting the formation of RNA secondary structures, which are unfavourable for transcription and translation. To test this commonly accepted theory, isolated CSPs from a mesophilic, thermophilic and a hyperthermophilic bacterium (Bacillus sub-tilis, Bacillus caldolyticusand Thermotoga maritima) were studied in an Escherichia colibased cell free expression system on their capability of enhancing protein expression by reduction of mRNA secondary structures. TheE
