Modification of the cholera toxin B subunit coding sequence to enhance expression in plants

The cholera toxin B subunit (CTB) contains five identical polypeptides and targets glycosphingolipid receptors on eukaryotic cell surfaces. Increased expression of CTB in plants is critical for the development of edible vaccines. In this study, the coding sequence of the CTB gene was optimized, base...

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Bibliographic Details
Published in:Molecular breeding 2004-02, Vol.13 (2), p.143-153
Main Authors: Kang, Tae-Jin, Loc, Nguyen-Hoang, Jang, Mi-Ok, Yang, Moon-Sik
Format: Article
Language:English
Subjects:
Cholera
Cholera toxin
Cholera toxin B subunit
CTB gene
Gene expression
Gene sequencing
Molecular biology
mRNA
Nicotiana
Optimization
Plant biology
Polypeptides
Proteins
Receptors
Tobacco
Toxins
Transgenic plants
Vaccines
Waterborne diseases
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Summary:The cholera toxin B subunit (CTB) contains five identical polypeptides and targets glycosphingolipid receptors on eukaryotic cell surfaces. Increased expression of CTB in plants is critical for the development of edible vaccines. In this study, the coding sequence of the CTB gene was optimized, based on the modification of codon usage to that of tobacco plant genes and the removal of mRNA-destabilizing sequences. The synthetic CTB gene was cloned into a plant expression vector and expressed in tobacco plants under the control of the CaMV 35S promoter. The recombinant CTB protein constituted approximately 1.5% of the total soluble protein in transgenic tobacco leaves. This level of CTB production was approximately 15-fold higher than that in tobacco plants that were transformed with the bacterial CTB gene. The recombinant CTB produced by tobacco plants demonstrated strong affinity for GM1-ganglioside, which indicates that the sites required for binding and proper folding of the pentameric CTB structure were conserved. This is the first report on the optimization of the CTB-coding sequence to give a dramatic increase in CTB expression in plants.
ISSN:1380-3743
1572-9788
DOI:10.1023/B:MOLB.0000018762.27841.7a