Glucan Phosphatase Variants Alter Starch Biophysics
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Solution Overview
Problem
Current methods for modifying starch for industrial applications require hazardous chemicals and physical extremes, and deleting glucan phosphatases like SEX4 results in excess starch synthesis and reduced biomass, necessitating the development of 'designer starches' with novel biophysical properties without using hazardous chemicals.
Innovation Solution
Development of glucan phosphatase polypeptide variants, such as Starch Excess 4 (SEX4) and Like Sex Four 2 (LSF2) variants with specific amino acid mutations, which alter starch metabolism and structure, allowing for the production of starch with altered biophysical properties and increased biomass without hazardous chemicals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hazardous chemicals and physical extremes are used to modify starch, then starch biophysical properties are improved, but safety and environmental harm worsen
Solution Approach 1:
The patent applies parameter changes by modifying the catalytic properties of glucan phosphatase enzymes through site-directed mutagenesis. Specific amino acid residues in the active site are mutated to alter substrate specificity and catalytic efficiency, enabling the enzyme to produce desired starch modifications without hazardous chemicals. This biochemical parameter change replaces harmful chemical treatments with controlled enzymatic reactions.
Solution Approach 2:
The patent substitutes mechanical and chemical systems with a biological system. Instead of using hazardous chemicals and physical extremes (mechanical/chemical system), the invention employs engineered glucan phosphatase variants that catalyze starch modification through biochemical reactions. This replacement eliminates harmful factors while achieving the desired starch biophysical property modifications.
2Productivity
If glucan phosphatases like SEX4 are deleted to increase starch synthesis, then starch production increases, but biomass decreases
Solution Approach 1:
Instead of deleting the glucan phosphatase gene entirely, the patent applies parameter changes by creating enzyme variants with modified catalytic parameters. The engineered phosphatases have altered substrate specificity and reduced activity toward certain starch phosphorylation sites, allowing starch accumulation without the complete loss of phosphatase function that would harm biomass. This fine-tuned parameter modification resolves the contradiction between starch production and biomass maintenance.
3Adaptability or versatility
If known chemicals are used to modify starch, then industrial applications are enabled, but safety concerns increase
Solution Approach 1:
The patent substitutes hazardous chemical modification systems with an engineered enzymatic system. The modified glucan phosphatase variants catalyze starch phosphorylation and dephosphorylation reactions under mild physiological conditions, replacing the need for hazardous chemicals. This biological substitution maintains adaptability for various industrial applications while eliminating safety concerns associated with chemical handling and disposal.
Solution Approach 2:
The engineered glucan phosphatase variants perform starch modification in a self-service manner through their catalytic activity. The enzymes naturally recognize and modify starch substrates according to their engineered specificity, eliminating the need for external hazardous chemical agents. This self-catalyzed modification process is inherently safer while maintaining versatility for different industrial starch application requirements.
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 glucan phosphatase variants increase starch production and alter biophysical properties, providing safer and cheaper starch-based feedstocks for industrial applications while maintaining efficient starch degradation.
Implementation Method 1
Starch is phosphorylated by glucan water dikinase (GWD), which phosphorylates the C6 position of glucose moieties and triggers C3 phosphorylation by phosphoglucan water dikinase (PWD)... glucan phosphatase activity is required for BAMs to completely degrade the glucan chains
Data Source
AI summary
Glucan phosphatase nucleotide or polypeptide variants of the presently-disclosed subject matter can alter the biophysical properties of starch in vitro or in planta, as well as the total starch biomass production in planta as compared to plants expressing wild-type glucan phosphatases. Plants producing the polypeptide variants of the presently-disclosed subject matter can have increased starch accumulation, increased starched biomass, and/or starch having desired biophysical properties. A method of the presently-disclosed subject matter for producing altered starch includes providing a plant that produces a glucan phosphatase polypeptide variant that comprises an amino acid mutation and collecting starch from the plant.