Safety assessment of dehydration-responsive element-binding (DREB) 4 protein expressed in E. coli

Dehydration-responsive element-binding (DREB) proteins are important transcription factors in plant responses and signal transduction. The DREB proteins can improve the drought and salt tolerance of plants, which provides an excellent opportunity to develop stress-tolerant genetically modified crops in the future. In the present study, a novel TaDREB4 gene (GenBank Accession No: AY781355.1) from Triticum aestivum was amplified by PCR (polymerase chain reaction), and the recombinant plasmid pET 30a(+)/TaDREB4 was successfully constructed. The fusion protein was induced by IPTG (isopropyl β-d-1-thiogalactopyranoside) and purified by the HisPrep™ FF 16/10 Column. The purity of the final purified TaDREB4 protein was 93.0%.Bioinformatic analysis and digestive stability tests were conducted to assess the allergenicity of the TaDREB4 protein, and acute toxicity tests were conducted in mice by oral administration of the TaDREB4 protein (5000 mg/kg BW). The results indicated that there was almost no similarity between the TaDREB4 protein and known allergens, and the protein was immediately degraded in simulated gastric and intestinal fluid within 15 s. In addition, no observed adverse effects were found in mice after 14 days. The results preliminary revealed that the protein is safe for human based on the current experiment.