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Expression of a synthetic E. coli heat-labile enterotoxin B sub-unit (LT-B) in maize
Molecular Breeding
  • Rachel Chikwamba, Iowa State University
  • Jennifer McMurray, Iowa State University
  • Huixia Shou, Iowa State University
  • Bronwyn Frame, Iowa State University
  • Sue Ellen Pegg, Iowa State University
  • Paul Scott, United States Department of Agriculture
  • Hugh Mason, Boyce Thompson Institute for Plant Research
  • Kan Wang, Iowa State University
Document Type
Article
Publication Version
Published Version
Publication Date
12-1-2002
Abstract

We have produced the B subunit of the enterotoxigenic Escherichia coli (ETEC) heat-labile enterotoxin (LT-B) in transgenic maize seed. LT-B is a model antigen that induces a strong immune response upon oral administration and enhances immune responses to conjugated and co-administered antigens. Using a synthetic LT-B gene with optimized codon sequence, we examined the role of promoters and the SEKDEL endoplasmic reticulum retention motif in LT-B accumulation in callus and in kernels. Two promoters, the constitutive CaMV 35S promoter and the maize 27 kDa gamma zein promoter, which directs endosperm-specific gene expression in maize kernels, regulated LT-B expression. Ganglioside-dependent ELISA analysis showed that using the constitutive promoter, maximum LT-B level detected in callus was 0.04% LT-B in total aqueous-extractable protein (TAEP) and 0.01% in R1 kernels of transgenic plants. Using the gamma zein promoter, LT-B accumulation reached 0.07% in R1 kernels. The SEKDEL resulted in increased LT-B levels when combined with the gamma zein promoter. We monitored LT-B levels under greenhouse and field conditions over three generations. Significant variability in gene expression was observed between transgenic events, and between plants within the same event. A maximum of 0.3% LT-B in TAEP was measured in R3 seed of a transgenic line carrying CaMV 35S promoter/LT-B construct. In R3 seed of a transgenic line carrying the gamma zein promoter/LT-B construct, up to 3.7% LT-B in TAEP could be detected. We concluded that maize seed can be used as a production system for functional antigens.

Comments

This article is published as Chikwamba, Rachel, Jennifer McMurray, Huixia Shou, Bronwyn Frame, Sue Ellen Pegg, Paul Scott, Hugh Mason, and Kan Wang. "Expression of a synthetic E. coli heat-labile enterotoxin B sub-unit (LT-B) in maize." Molecular breeding 10, no. 4 (2002): 253-265.

Rights
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Language
en
File Format
application/pdf
Citation Information
Rachel Chikwamba, Jennifer McMurray, Huixia Shou, Bronwyn Frame, et al.. "Expression of a synthetic E. coli heat-labile enterotoxin B sub-unit (LT-B) in maize" Molecular Breeding Vol. 10 Iss. 4 (2002) p. 253 - 265
Available at: http://works.bepress.com/paul-scott/63/