Enhancement of the solubility of proteins overexpressed in Escherichia coli by heat shock.

Protein misfolding resulting in the formation of inclusion bodies is one of the major problems during protein overexpression in Escherichia coil. In this paper, we introduce a new method, which is simply to heat shock a cell culture prior to protein induction, allowing effective enhancement of the solubility and thereby the yield of overexpressed proteins in E. coli. Using this method, we show that the solubility of the E. coli protein KsgA-AN is significantly increased when overexpressed from a T7 promoter. In addition, we also show that the solubility of several Caenorhabditis elegans proteins are also enhanced after heat-shock treatment when expressed in E. coli. Taken together, these results suggest that the "heat-shock protocol" is a generalizable and useful method for increasing the solubility of many proteins overexpressed in E. coli.