Chaperone DnaK and ATP participate in in vivo folding of firefly luciferase synthesized by E. coli cells

The time-courses of protein accumulation and luciferase activity of Luciola mingrelica firefly luciferase synthesized on plasmid pJGγ in E. coli strains Ω238 and B178groE7 (DnaK- and GroEL-deficient, correspondingly) and Ω237 and W3110 that are control to them, have been studied. It was shown that the amounts of the luciferase protein synthesized by all strains was approximately equal to 3.0-3.9% of the total cell protein. Luciferase was synthesized in a catalytically inactive form and transformed into an active enzyme during incubation at 21°C. In the DnaK-deficient E. coli strain Ω238, the enzyme transformation into a catalytically active form did not occur which provides evidence for participation of the DnaK chaperone in transformation of newly synthesized luciferase into catalytically active form. Luciferase folding was accelerated with an increase in ATP concentration inside the cell. It is possible to increase the ATP concentration inside the cell by treatment with polymyxin and addition of ATP to the culture medium, which significantly accelerates the luciferase folding.