The Expressed Protein in Glyphosate-Tolerant Soybean, 5-Enolypyruvylshikimate-3-Phosphate Synthase from Agrobacterium sp. Strain CP4, Is Rapidly Digested In Vitro and Is not Toxic to Acutely Gavaged Mice

Abstract

The safety of 5-enolpyruvylshikimate-3-phosphate synthase enzyme derived from Agrobacterium sp. strain CP4 (CP4 EPSPS) was assessed. CP4 EPSPS is the only protein introduced by genetic manipulation that is expressed in glyphosate-tolerant soybeans, which are being developed to provide new weed-control options for farmers. Expression of this protein in plants imparts high levels of glyphosate tolerance. The safety of CP4 EPSPS was ascertained by evaluating both physical and functional characteristics. CP4 EPSPS degrades readily in simulated gastric and intestinal fluids, suggesting that this protein will be degraded in the mammalian digestive tract upon ingestion as a component of food or feed. There were no deleterious effects due to the acute administration of CP4 EPSPS to mice by gavage at a high dosage of 572 mg/kg body wt, which exceeds 1000-fold the anticipated consumption level of food products potentially containing CP4 EPSPS protein. CP4 EPSPS does not pose any important allergen concerns because this protein does not possess characteristics typical of allergenic proteins. These data, in combination with seed compositional analysis and animal feeding studies, support the conclusion that glyphosate-tolerant soybeans are as safe and nutritious as traditional soybeans currently being marketed.