Protein expression in Escherichia coli at 15-25°C is widely used to increase the solubility of recombinant proteins. However, many recombinant proteins are insolubly expressed even at those low temperatures. Here, we show that recombinant proteins can be expressed as soluble forms by simply lowering temperature to 6-10°C without cold adapted chaperon systems. By using E. coli Rosetta-gami2(DE3), we obtained 1.8 and 0.9 mg of Cryptopygus antarticus mannanase (CaMan) and cellulase (CaCel) from 1 l culture grown at 6 and 10°C, respectively. Cultivation at 10°C also led to successful expression of EM3L7 (a lipase isolated from a metagenomic library) in a soluble form in E. coli BL21(DE3). Consequently, E. coli cultivation at 6-10°C is an effective strategy for overcoming a major hurdle of the inclusion body formation.
Bibliographical noteFunding Information:
We are grateful to Mr. Jung Ho Jeon of Korea Ocean Research and Development Institute (Korea) for contributing the pET-EM3L7 expression vector. This work was supported by the grant ( PP00740 ) from the Korea Ocean Research and Development Institute and by the Marine & Extreme Genome Research Center Program from the Ministry of Land, Transport, and Maritime Affairs.
- E. coli
- Extremely low temperature
- Protein expression