Mutant HPPD Polypeptide Herbicide Tolerance via Amino Acid Substitution
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Solution Overview
Problem
Current methods for providing plants with tolerance to HPPD-inhibitor herbicides are inadequate, as existing mutant HPPD enzymes offer insufficient tolerance to different herbicides, varying in spectrum of weed control, manufacturing costs, and environmental benefits.
Innovation Solution
A mutant hydroxyphenylpyruvate dioxygenase polypeptide with specific mutations at positions 372 and optionally 413 of the amino acid sequence, such as F372A or G413W, which confers enhanced tolerance to HPPD-inhibitor herbicides like topramezone, mesotrione, and isoxaflutole, allowing for broader herbicide tolerance in plants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing mutant HPPD enzymes are used, then some level of herbicide tolerance is achieved, but the tolerance is insufficient for different HPPD-inhibitor herbicides
Solution Approach 1:
The patent applies parameter changes by modifying specific amino acid residues in the HPPD enzyme sequence (positions 372 and 413) to alter the enzyme's properties. This allows the enzyme to maintain catalytic function while gaining resistance to HPPD-inhibitor herbicides, thereby improving herbicide tolerance without sacrificing adaptability to different weed spectra
Solution Approach 2:
The patent creates a universal HPPD enzyme variant that provides broad-spectrum herbicide tolerance across multiple HPPD-inhibitor chemistries (triketones, isoxazoles, pyrazolinates). The mutated enzyme maintains its natural function in tocopherol and plastoquinone biosynthesis while gaining additional protective function against diverse herbicides
2Reliability
If HPPD enzyme is overexpressed, then functional enzyme quantity increases, but manufacturing complexity increases
Solution Approach 1:
Instead of changing the quantity of enzyme through overexpression, the patent changes the quality of the enzyme by introducing specific mutations. This approach maintains normal expression levels while achieving herbicide tolerance, thereby avoiding the complexity associated with overexpression systems
Solution Approach 2:
The patent creates a modified copy of the native HPPD enzyme with specific amino acid substitutions at positions 372 and 413. This copied enzyme retains all natural functions while gaining herbicide resistance, eliminating the need for complex overexpression systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The mutant polypeptide enables plants to grow and thrive in the presence of HPPD-inhibitor herbicides, reducing plant damage and increasing yield, thereby expanding the scope of herbicides to which plants are tolerant and improving agricultural productivity.
Implementation Method 1
The hydroxyphenylpyruvate dioxygenases (abbreviated as HPPDs) are enzymes which, in the presence of iron ion (Fe2+) and oxygen, catalyze the reaction in which 4-hydroxyphenylpyruvic acid (abbreviated as HPP), a tyrosine degradation product, is transformed into homogentisic acid / homogentisate (abbreviated as HG)
Data Source
AI summary
Provided is a mutant hydroxyphenylpyruvate dioxygenase (HPPD) polypeptide, an encoding gene thereof and a use thereof. The mutant HPPD polypeptide retains the activity of catalyzing the conversion of hydroxyphenylpyruvate acid into homogentisic acid or homogentisate, and the sensitivity to HPPD inhibitor herbicides is lower than that of original unmutated HPPD. On position 372 corresponding to the amino acid sequence represented by SEQ ID NO: 1, the mutant HPPD polypeptide comprises the following mutations: F372A, F372G, F372V, F372P, F372S, F372T, F372C, F372M, F372Q, F372D or F372 deletion. The described mutant can provide plants with high tolerance to HPPD inhibitor herbicides, and can be used to cultivate plants that are tolerant to HPPD inhibitor herbicides.