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Optimizing HMG-CoA Synthase Expression for Enhanced Limonene Production in Escherichia coli through Temporal
Ari Dwijayanti1, Jing Wui Yeoh2,3, Congqiang Zhang4
1CNRS@CREATE, 1 Create Way, #08-01 Create Tower, Singapore 138602, Singapore.
ACS Synthetic Biology
|November 5, 2024
Summary
Optimizing enzyme expression in metabolic pathways is crucial for maximizing compound production. This study used optogenetics to control HMG-CoA synthase expression in E. coli, achieving high limonene yields.
Area of Science:
- Metabolic Engineering
- Synthetic Biology
- Optogenetics
Background:
- Balancing enzyme expression is critical for efficient heterologous metabolic pathways.
- Toxic intermediates and reduced productivity result from imbalanced enzyme levels.
- Optimal enzyme concentration depends on expression strength, timing, and degradation.
Purpose of the Study:
- To enhance limonene production in Escherichia coli by modulating HMG-CoA synthase (HMGS) expression.
- To investigate the impact of expression level and transcription duration on pathway performance.
- To apply optogenetic control for precise enzyme concentration management.
Main Methods:
- Utilized a blue-light inducible BLADE/pBad system to control HMGS expression.
- Tested various light intensities and photoperiods for enzyme induction.
- Employed a mathematical model to predict optimal expression conditions.
- Evaluated limonene production and cell fitness under different induction strategies.
Main Results:
- Intermediate HMGS transcription under moderate light yielded 160 mg/L limonene.
- Specific log-phase HMGS expression (3-9 h) under strong light achieved 200 mg/L limonene.
- Time-limited strong induction (3-9 h) increased limonene production by 92% (250 mg/L) without affecting cell fitness.
- Mathematical modeling supported optimal expression windows for maximizing yield and maintaining cell health.
Conclusions:
- Precise control over enzyme expression levels and timing is essential for optimizing metabolic pathways.
- Optogenetic control offers a powerful tool for fine-tuning enzyme concentrations ('right amount') and expression periods ('just-in-time').
- This approach is applicable for enhancing the production of limonene and other terpenoids in E. coli.
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