Supplementary data on the characterization and safety evaluation of HPPD W336, a modified 4-hydroxyphenylpyruvate dioxygenase protein, which confers herbicide tolerance, and on the compositional assessment of field grown MST-FGØ72-2 soybean expressing HPPD W336.

Supplementary data are provided which are supportive to the research article entitled "Characterization and safety evaluation of HPPD W336, a modified 4-hydroxyphenylpyruvate dioxygenase protein, and the impact of its expression on plant metabolism in herbicide-tolerant MST-FGØ72-2 soybean" (Dreesen et al., 2018) [1]. The conducted supplementary analyses include the characterization of additional Escherichia coli-produced HPPD W336 protein batches used as a surrogate in HPPD W336 safety studies, the assessment of potential glycosylation and monitoring of stability in simulated intestinal fluid and during heating of the HPPD W336 protein. Furthermore, data are provided on conducted field trials and subsequent compositional analysis in MST-FGØ72-2 soybean grain of compounds related to the tyrosine degradation pathway and the metabolism of homogentisate.

Characterization and safety evaluation of HPPD W336, a modified 4-hydroxyphenylpyruvate dioxygenase protein, and the impact of its expression on plant metabolism in herbicide-tolerant MST-FGØ72-2 soybean.

By transgenic expression technology, a modified 4-hydroxyphenylpyruvate dioxygenase enzyme (HPPD W336) originating from Pseudomonas fluorescens is expressed in MST-FGØ72-2 soybean to confer tolerance to 4-benzoyl isoxazole and triketone type of herbicides. Characterization and safety assessment of HPPD W336 were performed. No relevant sequence homologies were found with known allergens or toxins. Although sequence identity to known toxins showed identity to HPPD proteins annotated as hemolysins, the absence of hemolytic activity of HPPD W336 was demonstrated in vitro. HPPD W336 degrades rapidly in simulated gastric fluid. The absence of toxicity and hemolytic potential of HPPD W336 was confirmed by in vivo studies. The substrate spectrum of HPPD W336 was compared with wild type HPPD proteins, demonstrating that its expression is unlikely to induce any metabolic shifts in soybean. The potential effect of expression of HPPD W336 on metabolic pathways related to tyrosine was investigated by comparing seed composition of MST-FGØ72-2 soybean with non-genetically modified varieties, demonstrating that expression of HPPD W336 does not change aromatic amino acid, homogentisate and tocochromanol levels. In conclusion, HPPD W336 was demonstrated to be as safe as other food proteins. No adverse metabolic effects were identified related to HPPD W336 expression in MST-FGØ72-2 soybean.