With an annual output of over 700,000 tons, glyphosate is the most widely used and largest herbicide in the world. Weed resistance and potential threats to the ecological environment and human health caused by the abuse of glyphosate have attracted great attention.
On May 29th, Professor Guo Ruiting’s team from the State Key Laboratory of Biocatalysis and Enzyme Engineering, jointly established by the School of Life Sciences of Hubei University and the provincial and ministerial departments, published the latest research paper in the Journal of Hazardous Materials, analyzing the first analysis of barnyard grass. (A malignant paddy weed)-derived aldo-keto reductase AKR4C16 and AKR4C17 catalyze the reaction mechanism of glyphosate degradation, and greatly improve the degradation efficiency of glyphosate by AKR4C17 through molecular modification.
Growing glyphosate resistance.
Since its introduction in the 1970s, glyphosate has been popular all over the world, and has gradually become the cheapest, most widely used and most productive broad-spectrum herbicide. It causes metabolic disorders in plants, including weeds, by specifically inhibiting 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), a key enzyme involved in plant growth and metabolism. and death.
Therefore, breeding glyphosate-resistant transgenic crops and using glyphosate in the field is an important way to control weeds in modern agriculture.
However, with the widespread use and abuse of glyphosate, dozens of weeds have gradually evolved and developed high glyphosate tolerance.
In addition, glyphosate-resistant genetically modified crops cannot decompose glyphosate, resulting in the accumulation and transfer of glyphosate in crops, which can easily spread through the food chain and endanger human health.
Therefore, it is urgent to discover genes that can degrade glyphosate, so as to cultivate high glyphosate-resistant transgenic crops with low glyphosate residues.
Resolving the crystal structure and catalytic reaction mechanism of plant-derived glyphosate-degrading enzymes
In 2019, Chinese and Australian research teams identified two glyphosate-degrading aldo-keto reductases, AKR4C16 and AKR4C17, for the first time from glyphosate-resistant barnyard grass. They can use NADP+ as a cofactor to degrade glyphosate to nontoxic aminomethylphosphonic acid and glyoxylic acid.
AKR4C16 and AKR4C17 are the first reported glyphosate-degrading enzymes produced by natural evolution of plants. In order to further explore the molecular mechanism of their degradation of glyphosate, Guo Ruiting’s team used X-ray crystallography to analyze the relationship between these two enzymes and cofactor high. The complex structure of the resolution revealed the binding mode of the ternary complex of glyphosate, NADP+ and AKR4C17, and proposed the catalytic reaction mechanism of AKR4C16 and AKR4C17-mediated glyphosate degradation.
Structure of AKR4C17/NADP+/glyphosate complex and reaction mechanism of glyphosate degradation.
Molecular modification improves the degradation efficiency of glyphosate.
After obtaining the fine three-dimensional structural model of AKR4C17/NADP+/glyphosate, Professor Guo Ruiting’s team further obtained a mutant protein AKR4C17F291D with a 70% increase in the degradation efficiency of glyphosate through enzyme structure analysis and rational design.
Analysis of glyphosate-degrading activity of AKR4C17 mutants.
“Our work reveals the molecular mechanism of AKR4C16 and AKR4C17 catalyzing the degradation of glyphosate, which lays an important foundation for the further modification of AKR4C16 and AKR4C17 to improve their degradation efficiency of glyphosate.” Corresponding author of the paper, Associate Professor Dai Longhai of Hubei University Said that they constructed a mutant protein AKR4C17F291D with improved glyphosate degradation efficiency, which provides an important tool for cultivating high glyphosate-resistant transgenic crops with low glyphosate residues and using microbial engineering bacteria to degrade glyphosate in the environment.
It is reported that Guo Ruiting’s team has long been engaged in the research on the structure analysis and mechanism discussion of biodegradation enzymes, terpenoid synthases, and drug target proteins of toxic and harmful substances in the environment. Li Hao, associate researcher Yang Yu and lecturer Hu Yumei in the team are the co-first authors of the paper, and Guo Ruiting and Dai Longhai are the co-corresponding authors.
Post time: Jun-02-2022