Propane Biosynthesis via CoA-Dependent Butyraldehyde Pathway
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Natural metabolic pathways for the renewable biosynthesis of propane do not exist, and previous microbial pathways for propane production are limited by the availability of butyraldehyde precursors and the poor activity of aldehyde deformylating oxygenase (ADO) with butyraldehyde.
Innovation Solution
Construction of novel CoA-dependent butyraldehyde pathways in E. coli that bypass fatty acid synthesis, utilizing enzymes such as acetyl-CoA acetyltransferase, 3-hydroxybutyrl-CoA dehydrogenase, 3-hydroxybutyryl-CoA dehydratase, trans-2-enoyl-CoA reductase, and aldehyde deformylating oxygenase (ADO) to produce propane independently of aldehyde-alcohol dehydrogenase and fatty acid synthesis, with ADO variants like ADOA134F for enhanced activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the Ehrlich pathway (keto acid route) is used for butyraldehyde production, then branched chain alcohols and aldehyde precursors are produced at higher yields, but ADO has strong preference for straight chain aldehyde substrates making it less attractive
Solution Approach 1:
The patent extracts and eliminates the branching step in the metabolic pathway by using straight-chain precursors (acetyl-CoA) instead of branched-chain precursors (isobutyryl-CoA). This ensures compatibility with ADO's substrate preference while still achieving butyraldehyde production through a modified straight-chain pathway.
Solution Approach 2:
The patent changes the substrate parameter from branched-chain keto acids to straight-chain keto acids, which are then converted to butyraldehyde through the engineered pathway. This parameter change makes the substrate compatible with ADO's strong preference for straight chain aldehyde substrates.
2Adaptability or versatility
If the CoA-dependent butanol pathway is used, then butyraldehyde can be produced via straight chain route, but the pathway is limited by total flux through fatty acid synthesis
Solution Approach 1:
The patent extracts and removes the limiting fatty acid synthesis step from the pathway. Instead of relying on FAS to provide butyryl-CoA, the invention uses an alternative route where butyraldehyde is produced independently of FAS flux limitations, thereby bypassing the productivity constraint.
Solution Approach 2:
The patent segments the butyraldehyde production pathway from the fatty acid synthesis pathway. By using separate enzymatic steps (including carboxylic acid reductase and other enzymes) that do not depend on FAS flux, the invention creates an independent route that avoids the bottleneck imposed by fatty acid synthesis capacity.
3Productivity
If ADO is used to convert butyraldehyde to propane, then propane can be produced, but the activity of ADO with butyraldehyde is poor
Solution Approach 1:
The patent changes the chemical structure parameter of the aldehyde substrate by ensuring production of straight-chain butyraldehyde rather than branched-chain isobutyraldehyde. This structural parameter change significantly improves ADO's catalytic activity and reliability, as ADO has strong preference for straight chain aldehyde substrates.
Solution Approach 2:
The patent introduces intermediary enzymes and steps (including carboxylic acid reductase and other pathway enzymes) that mediate the conversion of metabolic intermediates to butyraldehyde in a form that is highly suitable for ADO catalysis. This intermediary pathway ensures optimal substrate presentation to ADO, improving its activity and reliability.
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 increased propane production by utilizing butyraldehyde as a precursor, overcoming previous limitations and expanding the metabolic toolbox for renewable propane and butanol production, with the atoB-TPC7-ADO pathway being the most effective in producing propane.
Implementation Method 1
The discovery of an aldehyde deformylating oxygenase (ADO) from cyanobacteria, however, has paved the way for synthetic alkane pathways to be constructed
Implementation Method 2
aldehyde deformylating oxygenase (ADO) to produce propane
Implementation Method 3
3-hydroxybutyryl-CoA dehydratase, trans-2-enoyl-CoA reductase
Implementation Method 4
trans-2-enoyl-CoA reductase, and aldehyde deformylating oxygenase (ADO) to produce propane
Data Source
AI summary
Provided are genetically engineered microorganism that catalyze the synthesis of propane and/or butanol from a suitable substrate such as glucose. Also provided are methods of engineering said genetically engineered microorganism and methods of producing propane and/or butanol using the genetically engineered microorganism.