Development of a heterologous expression system and optimization of the algorithm for cholera toxin β-subunit production in <i>E. coli</i>

Abstract

Cholera is a deadly infection disease, which is usually associated with low hygiene levels and restricted access to high-quality drinking water. An effective way to prevent cholera is the use of vaccines. Among active vaccine components there is the CtxB protein (cholera toxin β-subunit). In the current work, we have developed a genetic system for the production of recombinant CtxB in E. coli cells and studied the conditions for the synthesis and purification of the target product at the laboratory culture level. It has been found that the optimal algorithm for isolation of the recombinant protein is to grow an E. coli culture in a synthetic M9 medium with glycerol, followed by CtxB purification out of the spent culture medium through Ni2+-ions affinity chromatography techniques. Forty-eight hours following CtxB expression induction, the concentration of the target product can be up to 50 mg/liter in the culture medium. The CtxB protein retains its pentameric structure while expressing and through purification. The latter makes it possible to consider the developed system as a promising tool for the industrial-level synthesis of recombinant CtxB for medical and research purposes.