Thermal Switch System for Dynamic Metabolic Flux Control
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Solution Overview
Problem
The yield and productivity of amino acids, particularly threonine, in microbial fermentation are limited by unbalanced cellular metabolic flux distribution and the competition between synthetic pathways and cellular energy-supplying pathways, leading to suboptimal product synthesis and inefficient cofactor utilization.
Innovation Solution
A thermal switch system is developed, utilizing a thermal switch vector with a temperature-sensitive circuit to dynamically regulate the expression of pyruvate carboxylase, allowing for staged control of metabolic flux distribution and cofactor supply, optimizing oxaloacetate production and reducing energy wastage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If heterologous pathways are overexpressed to increase product synthesis, then production yield is improved, but cellular energy-supplying pathways are competed with, resulting in growth arrest and reduced productivity
Solution Approach 1:
The patent employs a thermal switch system that dynamically regulates gene expression based on temperature changes. During growth phase at lower temperature (30°C), the system maintains balanced metabolism for cell proliferation. When switching to production phase at higher temperature (42°C), the system dynamically activates heterologous pathways to maximize product yield without permanently compromising cellular energy pathways, thus resolving the contradiction between yield and productivity
Solution Approach 2:
The patent implements periodic control of metabolic pathways through temperature cycling. The fermentation process is divided into distinct phases: growth phase with one temperature regime and production phase with another. This periodic switching allows the system to alternately prioritize cell growth and product synthesis, ensuring both growth and productivity are optimized at different time points in the overall process
2Ease of operation
If static control methods are used to regulate gene expression, then gene expression level is effectively controlled, but the system cannot respond to dynamic metabolic environments, resulting in suboptimal product synthesis
Solution Approach 1:
The patent transforms static gene expression control into a dynamic system by utilizing temperature as a controllable parameter. The thermal switch contains temperature-sensitive elements that automatically adjust gene expression levels in response to metabolic state changes reflected by temperature. This dynamic regulation allows the system to adapt to changing metabolic environments during fermentation, optimizing product synthesis at each stage rather than maintaining fixed expression levels
Solution Approach 2:
The thermal switch system incorporates feedback mechanisms where temperature changes (reflecting metabolic state) automatically trigger appropriate gene expression responses. As metabolism progresses and temperature changes, the system senses these changes and adjusts pathway activation accordingly, creating a self-regulating system that optimizes product synthesis based on real-time metabolic conditions without requiring external intervention
3Productivity
If thermosensitive biosensor is used for temperature-dependent regulation, then metabolic burden is reduced during cell growth, but temperature changes cause unknown influence on overall cellular metabolism and promoter leakage expression
Solution Approach 1:
The patent introduces a carefully designed thermal switch circuit as an intermediary between temperature changes and gene expression. This switch uses temperature-sensitive repressors and promoters with defined thermal characteristics to mediate the relationship between temperature and metabolism. The intermediary design allows temperature-dependent regulation during growth while minimizing direct exposure of cellular metabolism to temperature fluctuations, thereby reducing promoter leakage and metabolic instability
Solution Approach 2:
The patent utilizes precise parameter changes in the thermal switch system, including specific temperature thresholds and transition ranges, to control gene expression. By optimizing the thermal characteristics of the switch components, the system achieves reliable activation only at production temperatures while maintaining stability during growth phase. The parameter optimization ensures that temperature changes trigger intended metabolic shifts without causing unwanted side effects or promoter leakage
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
This approach significantly enhances threonine yield and conversion rates, achieving up to 124.03% molar glucose-acid conversion rate and reducing by-product formation, thereby improving the efficiency and productivity of threonine production.
Implementation Method 1
The activity of a thermosensitive biosensor is controlled by temperature... the temperature-sensitive repressor gene cIts... When the temperature regulating the thermosensitive biosensor changes, it may cause unknown influence on overall cellular metabolism
Data Source
AI summary
The disclosure relates to a thermal switch system and application thereof in improving yield of amino acid, and particularly relates to a method for improving the yield of amino acid by regulating intracellular metabolic flux distribution using the thermal switch system, which belongs to the technical fields of genetic engineering and microbial fermentation. The system rebalances metabolic flux between pyruvate and oxaloacetate by controlling heterologous expression of pyruvate carboxylase and in combination with chemical properties that oxaloacetate is temperature-sensitive and easy to decarboxylate, and dynamically regulates a central metabolic pathway to ensure the supply of reducing cofactors, so as to promote the production of L-threonine. Temperature-controlled threonine-producing strains TWF106/pFT24rp and TWF113/pFT24rpa1 obtained in the disclosure have threonine molar conversion rates of 111.78% and 124.03% respectively.