Comparative chaperone activities of trigger factors from mesophilic and psychrophilic bacteria

The refolding level of thermally inactivated bacterial luciferases by trigger factor (TF) of the mesophilic bacterium Escherichia coli (TF Ec ) and the psychrophilic bacterium Psychrobacter frigidicola (TF Pf ) was measured. Heterodimeric (αβ) bacterial luciferases of Aliivibrio fischeri , Photobacterium leiognathi , and Vibrio harveyi as well as monomeric luuciferases of Vibrio harveyi and Luciola mingrelica (firefly) were used as substrates. 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). However, while the activity of TF Ec was characterized by a significant reduction in refolding with an increase in TF concentration, the chaperone activity of the TF Pf remained at a plateau at higher concentrations. TF Ec and TF Pf effectively assisted in refolding dimeric forms of luciferase but were unable to refold an enzyme variant in monomeric form. These observations were made both in vivo ( Escherichia coli ΔdnaKJ containing plasmids with tig gene) and in vitro (purified TF). It was shown that TF Pf but not TF Ec is a target for the action of Lon protease.