Molecular Cloning, Structural Modeling and the Production of Soluble Triple-Mutated Diphtheria Toxoid (K51E/G52E/E148K) Co-expressed with Molecular Chaperones in Recombinant Escherichia Coli
Overview
Molecular Biology
Authors
Affiliations
CRM197 is a diphtheria toxin (DT) mutant (G52E) which has been used as a carrier protein for conjugate vaccines. However, it still possesses cytotoxicity toward mammalian cells. The goal of this project was to produce a non-toxic and soluble CRM197EK through introduction of triple amino acid substitutions (K51E/G52E/E148K) in Escherichia coli. The expression of CRM197EKTrxHis was optimized and co-expressed with different molecular chaperones. The soluble CRM197EKTrxHis was produced at a high concentration (97.33 ± 17.47 μg/ml) under the optimal condition (induction with 0.1 mM IPTG at 20 °C for 24 h). Cells containing pG-Tf2, expressing trigger factor and GroEL-GroES, accumulated the highest amount of soluble CRM197EKTrxHis at 111.24 ± 10.40 μg/ml after induction for 24 h at 20 °C. The soluble CRM197EKTrxHis still possesses nuclease activity and completely digest λDNA at 25 and 37 °C with 8- and 4-h incubation, respectively. Molecular modeling of diphtheria toxin, CRM197 and CRM197EK indicated that substitutions of two amino acids (K51E/E148K) may cause poor NAD binding, consistent with the lack of toxicity. Therefore, CRM197EK might be used as a new potential carrier protein. However, further in vivo study is required to confirm its roles as functional carrier protein in conjugate vaccines.
Khodak Y, Ryazanova A, Vorobiev I, Kovalchuk A, Ovechko N, Aparin P BioTech (Basel). 2023; 12(1).
PMID: 36648835 PMC: 9844443. DOI: 10.3390/biotech12010009.
Fatima K, Naqvi F, Younas H Cell Biochem Biophys. 2021; 79(2):153-174.
PMID: 33634426 DOI: 10.1007/s12013-021-00970-5.
Oligomerization of a molecular chaperone modulates its activity.
Saio T, Kawagoe S, Ishimori K, Kalodimos C Elife. 2018; 7.
PMID: 29714686 PMC: 5988418. DOI: 10.7554/eLife.35731.