Effect of DnaK chaperone system on protein evolution

Molecular chaperones help proteins fold and can thereby influence their adaptive evolution. In this work we explore how the bacterial Hsp70 chaperone system consisting of the proteins, DnaK, DnaJ and GrpE (KJE), affects the directed evolution of green fluorescent protein (GFP). We evolved GFP under both high and low expression of KJE. In the first phase of this study, we evolved GFP variants under a stabilizing for the ancestral phenotype of green fluorescence, and in the second phase we evolved them with directional selection towards the new phenotype of cyan fluorescence.