Acetyl-CoA Producing Microorganism with Engineered CO2 Fixation Pathway
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Solution Overview
Problem
Existing carbon dioxide fixation cycles for producing acetyl-CoA from CO2 are inefficient due to low enzyme reaction rates, side reactions, and difficulties in introducing anaerobic pathways into non-anaerobic microorganisms, leading to challenges in regulating and constructing effective metabolic pathways.
Innovation Solution
A microorganism is engineered with an acetyl-CoA production cycle that includes specific enzymatic activities such as malate thiokinase, malyl-CoA lyase, glyoxylate carboligase, and 2-hydroxy-3-oxopropionate reductase, which efficiently converts CO2 into acetyl-CoA without requiring enzymes that consume acetyl-CoA or complex pathways, allowing for simpler integration with existing metabolic pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing carbon dioxide fixation cycles (Calvin-Benson cycle, reductive TCA cycle, Wood-Ljungdahl pathway) are introduced to produce acetyl-CoA from CO2, then CO2 fixation capability is achieved, but enzyme reaction rates are low and side reactions occur
Solution Approach 1:
The patent changes the biochemical parameters of the CO2 fixation pathway by replacing conventional enzymes with alternative enzymes that have different kinetic properties. Specifically, it uses phosphoenolpyruvate carboxylase instead of RubisCO for CO2 fixation, and introduces a novel cycle with enzymes like malyl-CoA lyase, glyoxylate carboligase, and 2-hydroxy-3-oxopropionate reductase that operate more efficiently with fewer side reactions, thereby improving both productivity and reliability
Solution Approach 2:
The patent extracts and eliminates problematic components from existing CO2 fixation cycles. It removes enzymes that cause side reactions or have low reaction rates, and selectively introduces only the necessary enzymes for the novel acetyl-CoA production cycle, creating a streamlined pathway that avoids the deficiencies of conventional cycles
2Productivity
If anaerobic carbon dioxide fixation pathways are introduced into non-anaerobic microorganisms, then CO2 to acetyl-CoA conversion is achieved, but pathway construction and regulation become difficult
Solution Approach 1:
The patent segments the CO2 fixation pathway into modular enzymatic steps that can be independently introduced and regulated. The novel cycle is divided into distinct enzymatic reactions (CO2 fixation by PEP carboxylase, malyl-CoA formation, cleavage to acetyl-CoA and glyoxylate, etc.), allowing systematic construction in non-anaerobic microorganisms without requiring complete anaerobic pathway introduction
Solution Approach 2:
The patent introduces intermediary metabolites and enzymes that bridge anaerobic CO2 fixation functionality with aerobic microorganism metabolism. The novel cycle uses intermediaries like malyl-CoA, glyoxylate, and 2-hydroxy-3-oxopropionate that can be processed in aerobic conditions, serving as mediators between the anaerobic-inspired pathway and aerobic host metabolism
3Productivity
If conventional CO2 fixation pathways are used, then CO2 fixation is achieved, but the number of enzymes required is large and pathway regulation is complex
Solution Approach 1:
The patent extracts only the essential enzymatic components needed for CO2 fixation and acetyl-CoA production, eliminating redundant enzymes from conventional cycles. The novel cycle requires fewer enzyme types by using alternative biochemical routes that achieve the same net transformation with greater efficiency
Solution Approach 2:
The patent merges the CO2 fixation function with the acetyl-CoA production pathway into a unified cycle. The introduced enzymes work together in an integrated manner where the output of one reaction directly feeds the next, creating a cohesive pathway that simultaneously achieves CO2 fixation and acetyl-CoA synthesis without requiring separate regulatory systems
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 enables efficient conversion of CO2 into acetyl-CoA with a reduced number of enzymes, improving production yields and simplifying pathway regulation, and allows for the production of valuable metabolites like isopropyl alcohol and glutamate.
Implementation Method 1
phosphoenolpyruvate carboxylase that fixes CO2 onto phosphoenolpyruvate
Implementation Method 2
pyruvate kinase that converts phosphoenolpyruvate into pyruvate
Implementation Method 3
pyruvate carboxylase that converts pyruvate into oxaloacetate by fixing CO2
Implementation Method 4
malate dehydrogenase that converts malate into oxaloacetate
Implementation Method 5
malate thiokinase that converts malate into malyl-CoA
Implementation Method 6
malyl-CoA lyase that cleaves malyl-CoA into acetyl-CoA and glyoxylate
Implementation Method 7
glyoxylate carboligase that condenses glyoxylate into 2-hydroxy-3-oxopropionate
Implementation Method 8
2-hydroxy-3-oxopropionate reductase that reduces 2-hydroxy-3-oxopropionate into glycerate
Implementation Method 9
enolase that converts 3-phosphoglycerate into phosphoenolpyruvate
Data Source
AI summary
An acetyl-CoA-producing microorganism, which is capable of efficiently synthesizing acetyl-CoA using carbon dioxide, and a substance production method using the same are provided. An acetyl-CoA-producing microorganism including an acetyl-CoA production cycle obtained by imparting at least one type of enzymatic activity selected from the group consisting of malate thiokinase, malyl-CoA lyase, glyoxylate carboligase, 2-hydroxy-3-oxopropionate reductase, and hydroxypyruvate reductase, to a microorganism.