Enhanced expression of B-subunit of Escherichia coli heat-labile enterotoxin in tobacco by optimization of coding sequence

Author： Kang Tae-Jin Han So-Chon Jang Mi-Ok Kang Kui-Hyeon Jang Yong-Suk Yang Moon-Sik

Publisher： Humana Press, Inc

ISSN： 0273-2289

Source： Applied Biochemistry and Biotechnology, Vol.117, Iss.3, 2004-06, pp. : 175-187

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Abstract

Escherichia coli heat-labile toxin (LT) is a potent mucosal immunogen and immunoadjuvant for coadministered antigens. We synthesized a gene encoding the B-subunit of LT(LTB) adapted to the coding sequence of tobacco plants and fused to the endoplasmic reticulum retention signal SEKDEL to enhance its level of expression in plants. The synthetic LTB gene was cloned into a plant expression vector adjacent to the CaMV 35S promoter and was introduced into tobacco by Agrobacterium-mediated transformation. The amount of LTB protein detected in transgenic tobacco leaves was 2.2% of the total soluble plant protein, which is approx 200-fold higher than in previous reports of native LTB gene expression in transgenic plants. Enzyme-linked immunosorbent assay indicated that plant-synthesized LTB protein bound specifically to G_M1-ganglioside, suggesting that the LTB subunits formed active pentamers.