Thu Sep 26 14:00:00 UTC 2024: ## Scientists Develop Scalable Method for Producing Protoporphyrinogen IX Oxidase (PPO) for Herbicide-Tolerant Crop Safety Studies
**Chesterfield, Missouri** – A team of researchers from Bayer Crop Science has developed a novel and robust method for large-scale production of protoporphyrinogen IX oxidase (PPO) protein, a key component in herbicide-tolerant crops. This breakthrough significantly streamlines the process of conducting safety studies on these crops, potentially saving hundreds of animals in the process.
PPO is a crucial enzyme in the biosynthesis of chlorophyll and heme. Herbicides targeting PPO have been used to control weeds in various crops, leading to increased yield and reduced herbicide usage. However, producing sufficient quantities of PPO for safety studies has been a significant obstacle due to its inherent tendency to aggregate, making purification and formulation challenging.
The researchers addressed this challenge by developing a scalable method using an N-terminal 6xHis-tag for PPO purification. They found that this tag does not affect PPO’s functional activity, allowing them to produce over 200 grams of highly active PPO protein with 99% purity and low endotoxin contamination. They also developed a formulation that allows for the concentration of active PPO to >75 mg/mL, making it suitable for mammalian toxicity studies.
The study also investigated the impact of minor N-terminal amino acid sequence differences on PPO’s functional properties. These variations occur naturally in transgenic crops due to incomplete processing of the chloroplast transit peptide (CTP) during protein synthesis. Using structural modeling and functional characterization, the researchers demonstrated that these N-terminal differences do not affect PPO’s function or activity.
This finding has significant implications for regulatory safety assessments. Instead of conducting separate safety studies for each PPO variant with minor N-terminal differences, the researchers propose that a single representative study using the mature PPO protein is sufficient. This novel approach will significantly reduce the number of animals required for safety testing and contribute to the ethical and efficient development of herbicide-tolerant crops.
The researchers believe this breakthrough will accelerate the development and commercialization of new herbicide-tolerant crops, contributing to sustainable agriculture and food production.
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