Molecular chaperones facilitate soluble expression of recombinant non-toxic mutant CRM197 of diphtheria toxin in Escherichia coli.

Mengting Yang; Xiaoxiao LI; Chen Lin; Mingjing Liu; Yezi Chen; Yun Zhao; Chaoqi Liu

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Molecular chaperones facilitate soluble expression of recombinant non-toxic mutant CRM197 of diphtheria toxin in Escherichia coli.

Author: Mengting YANG ¹ ; Xiaoxiao LI ¹ ; Chen LIN ² ; Mingjing LIU ¹ ; Yezi CHEN ¹ ; Yun ZHAO ² ; Chaoqi LIU ¹
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1. Hubei Provincial Key Laboratory of Tumor Microenvironment and Immunotherapy, School of Medicine, China Three Gorges University, Yichang 443002, Hubei, China.
2. School of Medicine, China Three Gorges University, Yichang 443002, Hubei, China.
Publication Type:Journal Article
Keywords: CRM197; molecular chaperone; prokaryotic expression; soluble protein
MeSH: Bacterial Proteins; Diphtheria Toxin/genetics*; Escherichia coli/genetics*; Humans; Molecular Chaperones/genetics*; Recombinant Proteins/genetics*
From: Chinese Journal of Biotechnology 2021;37(4):1368-1375
CountryChina
Language:Chinese
Abstract: Diphtheria toxin is an ADP-ribosyltransferase toxic to human cells. Mutation of the active site in its catalytic domain eliminates the toxicity, but retains its immunogenicity. A non-toxic mutant of diphtheria toxin known as CRM197 protein has become an ideal carrier protein for conjugate vaccines. CRM197 can further improve its immunogenicity by cross-linking with other antigens, so it has good potential to find broad applications. Unfortunately, inclusion bodies are easily formed during the expression of recombinant CRM197 protein in Escherichia coli, which greatly reduces its yield. In order to address this problem, pG-KJE8 vector carrying molecular chaperones and plasmid pET28a-CRM197, were co-expressed in Escherichia coli. The results showed that the recombinant CRM197 protein was successfully expressed and appeared largely in inclusion bodies. The molecular chaperones DnaK, DnaJ, GrpE, GroES and GroEL5 expressed can facilitate correct and rapid folding of CRM197. Furthermore, it can also improve the recovery rate of soluble CRM197 protein. The soluble expression of CRM197 was maximized upon addition of 1.0 mmol/L IPTG, 0.5 mg L-arabinose, 5.0 ng/mL tetracycline and induction at 20oC for 16 h. The soluble CRM197 protein shows good immunoreactivity, demonstrating the molecular chaperones expressed from pG-KJE8 facilitated the soluble expression of CRM197 protein in E. coli.