Metabolic control analysis for lysine synthesis using Corynebacterium glutamicum and experimental verification

Area of Science:

• Biotechnology
• Metabolic Engineering
• Microbial Physiology

Background:

• Lysine is a crucial amino acid for industrial applications.
• Corynebacterium glutamicum is a key microorganism for lysine overproduction.
• Understanding metabolic regulation is vital for strain improvement.

Purpose of the Study:

• To identify rate-limiting steps in the lysine biosynthetic pathway of Corynebacterium glutamicum.
• To investigate the influence of various parameters on lysine synthesis flux.
• To validate computational findings through experimental manipulation of key enzymes.

Main Methods:

• Metabolic control analysis using mechanism-based kinetic models.
• Calculation of flux control coefficients and response coefficients.
• Construction and analysis of recombinant strains overexpressing key enzymes.

Main Results:

• Aspartokinase and export permease activity were identified as major determinants of lysine synthesis flux.
• Increasing aspartokinase activity shifted flux control to other enzymes, including permease.
• Decreasing extracellular lysine concentration significantly enhanced lysine production.
• Optimal external pH for lysine production was determined to be 7.0.

Conclusions:

• Metabolic control analysis provides insights into optimizing lysine biosynthesis in C. glutamicum.
• Targeting aspartokinase and managing extracellular lysine are effective strategies for enhancing production.
• Experimental validation confirmed the predictive power of the metabolic models.