Evaluation of similarities in the cis/trans isomerase function of trigger factor and DnaK

Two functionally redundant enzymes, trigger and the hsp70 chaperone DnaK, have been assist de novo protein folding in E. coli. Trigger is a peripheral peptidyl prolyl cis/trans isomerase (PPIase) of the large subunit of the ribosome. contrast, DnaK displays two catalytic features: secondary amide peptide bond cis/trans isomerase (APIase) function supplemented by the ATPase APIases accelerate the cis/trans isomerization nonprolyl peptide bonds. Both enzymes have for an unfolded polypeptide chain. The diminished temperature cell viability in the presence factor variants with impaired PPIase activity that the enhancement of folding rates plays role in protein folding in vivo. For the DnaK increase in the folding yield in vitro, the minimal model for APIase catalysis involves the catalyzed partitioning of a rapidly formed folding intermediate could be inferred from the DnaK/DnaJ/GrpE/ATP-assisted refolding of GdmCl-denatured luciferase. Using three different peptide bond cis/trans isomerization assays in vitro, we could show that no overlapping substrate specificity of trigger and DnaK. We propose that only if trigger recruits supplementing molecules is it capable exhibiting functional complementarity with DnaK protein folding.