Lysine Microorganism Gluconate Kinase Weakening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing L-lysine in Corynebacterium strains are limited by the efficiency of NADPH supply, which is crucial for its biosynthesis, as they rely heavily on the TCA cycle and pentose phosphate pathway, with potential for increased yield through genetic modification of enzymes involved in the pentose phosphate pathway but not effectively addressing the gluconate kinase activity.
Innovation Solution
A method involving the weakening of gluconate kinase (GntK) activity by mutating the corresponding gene in Corynebacterium spp. to enhance NADPH production, achieved by constructing a recombinant vector for homologous recombination and selecting strains with reduced GntK activity, thereby increasing the intracellular NADPH levels and L-lysine productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the TCA cycle is used as the main supply route for NADPH, then L-lysine production can be maintained, but the carbon metabolism yield is low because two CO2 molecules are released per one NADPH molecule produced
Solution Approach 1:
The patent changes the metabolic parameter by shifting the main NADPH supply route from the TCA cycle to the pentose phosphate pathway. This is achieved through genetic modification of enzymes in the pentose phosphate pathway, specifically enhancing G6PDH activity and mutating 6PGD to increase NADPH production efficiency while reducing carbon loss as CO2.
Solution Approach 2:
Instead of relying on the conventional TCA cycle for NADPH supply, the patent inverts the approach by making the pentose phosphate pathway the primary source. This inversion is accomplished by overexpressing key enzymes (zwf, gnd genes) and modifying 6PGD activity to reverse the traditional metabolic flow preference.
2Productivity
If genes encoding enzymes in the pentose phosphate pathway are enhanced or mutated, then L-amino acid productivity is increased, but the metabolic balance and cell growth may be disrupted
Solution Approach 1:
The patent applies local quality modification by specifically targeting certain enzymes in the pentose phosphate pathway rather than uniformly enhancing all pathways. G6PDH is overexpressed to increase NADPH production at the first step, while 6PGD is mutated to optimize the second step, creating localized enhancements that maintain overall metabolic balance.
Solution Approach 2:
The patent implements feedback control by monitoring NADPH levels and adjusting enzyme activities accordingly. The metabolic flux is regulated through feedback mechanisms where NADPH consumption in L-lysine biosynthesis signals the need for increased production capacity in the pentose phosphate pathway, creating a self-regulating system.
3Quantity of substance
If gluconate kinase (GntK) activity is maintained at endogenous levels, then general metabolism is preserved, but NADPH production for L-lysine biosynthesis is insufficient
Solution Approach 1:
The patent extracts the gluconate kinase activity from the main metabolic pathway by introducing a separate pathway using exogenous enzymes (PglK from E. coli or SacK from S. cerevisiae). This extracted function specifically targets gluconate conversion to generate NADPH without interfering with the endogenous GntK-mediated metabolism, thereby increasing NADPH supply for L-lysine production.
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 increases L-lysine production efficiency by enhancing NADPH regeneration, leading to higher yields and productivity in L-lysine-producing microorganisms.
Implementation Method 1
The enzymes important to the biosynthesis of L-lysine are aspartate semialdehyde dehydrogenase, dihydrodipicolinate reductase and diaminopimelate dehydrogenase, which are respectively encoded by the genes asd, dapB and ddh, and which are NADPH-dependent reductases
Implementation Method 2
the operation of two cycles of the pentose phosphate pathway releases one CO2 molecule with the concomitant production of two NADPH molecules
Implementation Method 3
two CO2 molecules are released per one TCA cycle, with the concomitant production of one NADPH molecule
Data Source
Figure 1
Figure 2~3
AI summary
Disclosed is an L-lysine-producing microorganism having gluconate kinase activity weakened in comparison to the endogenous activity thereof, and methods provided for preparing the microorganism and for producing L-lysine using the same.