Transgenic Expression of Bean α-Amylase Inhibitor in Peas Results in Altered Structure and Immunogenicity

Abstract

The development of modern gene technologies allows for the expression of recombinant proteins in non-native hosts. Diversity in translational and post-translational modification pathways between species could potentially lead to discrete changes in the molecular architecture of the expressed protein and subsequent cellular function and antigenicity. Here, we show that transgenic expression of a plant protein (alpha-amylase inhibitor-1 from the common bean (Phaseolus vulgaris L. cv. Tendergreen)) in a non-native host (transgenic pea (Pisum sativum L.)) led to the synthesis of a structurally modified form of this inhibitor. Employing models of inflammation, we demonstrated in mice that consumption of the modified alphaAI and not the native form predisposed to antigen-specific CD4+ Th2-type inflammation. Furthermore, consumption of the modified alphaAI concurrently with other heterogeneous proteins promoted immunological cross priming, which then elicited specific immunoreactivity of these proteins. Thus, transgenic expression of non-native proteins in plants may lead to the synthesis of structural variants possessing altered immunogenicity.

Biotechnological Prospects for Engineering Insect-Resistant Plants

“…Safety concerns have arisen as a result of the induction of systemic immunological responses in mice fed peas expressing the amylase inhibitor protein (Prescott et al, 2005), which appear to result from altered posttranslational processing in pea compared to the ''natural'' host (bean).…”

Genetically modified foods and allergy

“…The second, in 2005, involved experiments on mice in which a bean engineered to resist pea weevil triggered an immune reaction in the lungs of the animals. 14 These examples are often cited to support claims that GM technology is dangerous and unpredictable. An alternative interpretation is that safety testing was effective in both cases before either product was released onto the market.…”

Risks from GMOs due to Horizontal Gene Transfer

“…HGT has the potential to transfer introduced genes from a GMO to a multitude of other species, some of which are potential pests or pathogens, and many organisms are yet to be identified and characterized. The genes introduced to bacteria could be transferred to indigenous bacteria, altering the ecological niche or ecological potential of the recipient organism (Heuer and Smalla, 2007) or through unexpected changes in structure or function (Prescott et al, 2005). The wide diversity of recipient genomes makes it difficult to predict the outcome from the introduction of a particular gene.…”