Mut- Yeast Metabolic Engineering for Reduced Oxygen Demand
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Solution Overview
Problem
Current methods for recombinant protein production in methylotrophic yeast, such as Pichia pastoris, face challenges including high oxygen demand, heat production, and inefficiencies in methanol utilization, which increase costs and complexity in downstream processing.
Innovation Solution
Engineering a recombinant methanol utilization pathway deficient methylotrophic yeast (Mut−) by reducing the expression of alcohol oxidase 1 (AOX1) and alcohol oxidase 2 (AOX2) genes and increasing the expression of an alcohol dehydrogenase (ADH2) gene, allowing for efficient methanol utilization and reduced oxygen and heat production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If methanol is used as carbon source for protein production in methylotrophic yeast, then protein yield is improved, but oxygen demand and heat production increase
Solution Approach 1:
The invention changes the metabolic parameters of the yeast by genetically modifying the alcohol oxidase enzymes (AOX1 and AOX2) to have altered substrate specificity. The modified enzymes can oxidize both methanol and alternative carbon sources (glycerol, ethylene glycol, 1,2-propanediol), effectively changing the physiological parameters of methanol utilization and reducing oxygen demand while maintaining protein production efficiency.
2Productivity
If methanol is used as carbon source for protein production in methylotrophic yeast, then protein yield is improved, but downstream processing complexity increases
Solution Approach 1:
By modifying the alcohol oxidase enzymes to accept alternative carbon sources, the invention changes the fermentation parameters to enable use of less hazardous substances. This reduces the complexity of downstream processing by eliminating or reducing the need for specialized methanol handling equipment and safety protocols, while maintaining high protein yield.
3Productivity
If methanol is used as carbon source for protein production in methylotrophic yeast, then protein production efficiency is improved, but costs increase
Solution Approach 1:
The genetic modification of alcohol oxidase enzymes enables the yeast to utilize cheaper alternative carbon sources such as glycerol, ethylene glycol, and 1,2-propanediol. This parameter change in substrate specificity directly reduces material costs while maintaining protein production efficiency, as these alternative substrates are generally less expensive than methanol.
4Use of energy by moving object
If AOX1 and AOX2 genes are reduced in expression, then oxygen demand is reduced, but methanol utilization efficiency decreases
Solution Approach 1:
The invention applies local quality by creating alcohol oxidase enzymes with altered local properties - specifically modified active sites that provide dual functionality. The modified AOX1 and AOX2 enzymes maintain their ability to oxidize methanol while gaining the ability to oxidize alternative carbon sources, allowing reduced expression levels to suffice for both methanol and alternative substrate utilization.
Solution Approach 2:
The modified alcohol oxidase enzymes achieve multi-functionality by being able to oxidize multiple substrates (methanol, glycerol, ethylene glycol, 1,2-propanediol). This universality allows the yeast to maintain efficient carbon source utilization even when AOX1 and AOX2 expression is reduced, as the modified enzymes can compensate by processing alternative substrates.
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 enhances recombinant protein production efficiency by reducing oxygen and heat requirements, improving methanol utilization, and increasing protein yield, thereby simplifying downstream processing and reducing costs.
Implementation Method 1
increasing the expression of an alcohol dehydrogenase (ADH2) gene, allowing for efficient methanol utilization
Implementation Method 2
oxidation of methanol to formaldehyde, reducing oxygen demand and heat production
Data Source
AI summary
A recombinant methanol utilization pathway deficient methylotrophic yeast (Mut−) host cell which is engineered: a) by one or more genetic modifications to reduce expression of a first and a second endogenous gene compared to the host cell prior to said one or more genetic modifications, wherein i. the first endogenous gene encodes alcohol oxidase 1 (AOX1) comprising the amino acid sequence identified as SEQ ID NO:1 or a homologue thereof, and ii. the second endogenous gene encodes alcohol oxidase 2 (AOX2) comprising the amino acid sequence identified as SEQ ID NO:3 or a homologue thereof, and b) by one or more genetic modifications to increase expression of an alcohol dehydrogenase (ADH2) gene compared to the host cell prior to said one or more genetic modifications, wherein the ADH2 gene encodes an alcohol dehydrogenase (ADH2).