The refolding level of thermally inactivated bacterial luciferases by trigger factor (TF) of the mesophilic bacterium Escherichia coli (TFEc) and the psychrophilic bacterium Psychrobacter frigidicola (TFPf) was measured. Refolding of heat inactivated luciferases reached a maximum of 25-30% in E. coli ΔdnaKdnaJ cells containing plasmids with a tig gene (encoding TF) and luxAB genes (encoding heterodimeric (αβ) luciferase from Photobacterium leiognathi). However, while the activity of TFEc was characterized by a significant reduction in refolding with an increase in TF concentration, the chaperone activity of the psychrophilic TF remained at a plateau at higher concentrations. TFPf also did not affect the growth kinetics of the host bacterial cells at high TF concentrations, unlike TFEc, which exerted a lethal effect on bacterial cells with increased concentration. Moreover, TFEc and TFPf effectively assisted in refolding dimeric forms of luciferase but were unable to refold an enzyme variant in monomeric form. Finally, luciferase refolding by TFPf was found to be more efficient in E. coli strains lacking the ClpB chaperone than in clpB+ strains.
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