Yeast Recombinant Promoter Expression Control
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Solution Overview
Problem
Current methods for producing recombinant proteins in yeast cells face challenges such as variable expression efficiency due to integration site effects, metabolic competition, and low transformation efficiencies, particularly when co-expressing protein disulfide isomerase (PDI) and the target protein, which can lead to reduced yields and product variability.
Innovation Solution
A genetically modified yeast cell with a recombinant promoter linked to a gene encoding a biosynthesis-supporting polypeptide or protein, such as PDI, is used, where the native promoter of the biosynthesis-supporting gene is inactivated to ensure controlled expression of the recombinant protein or polypeptide, enhancing yield and reducing metabolic competition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If recombinant expression cassettes comprising a gene encoding PDI are integrated into the genome of yeast cells, then PDI expression is achieved, but integration site effects cause variable expression efficiency and product variability
Solution Approach 1:
The patent extracts the PDI expression system from integrated genomic cassettes and places it on an episomal plasmid backbone. This removes the expression system from the problematic integration site context, allowing consistent expression without genomic position effects. The PDI gene is expressed from a plasmid that replicates independently of chromosomal integration events.
Solution Approach 2:
The patent combines the PDI expression cassette and the target protein expression cassette into a single plasmid construct. This merging ensures that both genes are co-expressed at defined ratios from the same replicon, eliminating variability caused by separate integration events at different genomic loci. The dual-expression plasmid maintains both genes together through cell division.
2Adaptability or versatility
If multiple nucleic acid constructs are co-transformed into yeast cells, then both PDI and target protein expression is achieved, but transformation efficiency decreases and false positive clones increase
Solution Approach 1:
The patent merges multiple expression cassettes (PDI and target protein) into a single plasmid construct with multiple origins of replication. This allows both genes to be introduced in one transformation event rather than requiring sequential co-transformation of separate plasmids. The multi-origin plasmid maintains both expression functions while simplifying the transformation process.
Solution Approach 2:
The plasmid construct is designed with universal functionality to perform multiple tasks: it contains origins of replication for maintenance, selection markers for identification, and multiple expression cassettes for simultaneous PDI and target protein production. This multi-functional design eliminates the need for separate constructs and selection markers for each gene.
3Reliability
If PDI is over-expressed from a recombinant expression cassette, then protein folding is improved, but metabolic competition for transcription or translation occurs
Solution Approach 1:
The patent employs inducible promoters for both PDI and target protein expression that can be dynamically controlled. By using promoters responsive to the same inducer (e.g., GAL1 promoter induced by galactose), the system allows coordinated upregulation of both genes when needed, and downregulation when metabolic burden becomes excessive. This dynamic control balances folding assistance with resource availability.
Solution Approach 2:
The patent optimizes expression parameters by adjusting promoter strength, ribosome binding site sequences, and codon usage to balance PDI and target protein expression levels. The system allows tuning of the PDI:target protein expression ratio to achieve optimal folding assistance without overwhelming the cell's translational capacity. Expression levels can be adjusted by changing cultural conditions or plasmid copy number.
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 the production of recombinant proteins by minimizing metabolic interference and ensuring consistent expression levels, resulting in higher yields compared to traditional methods, with the genetically modified yeast cells producing up to 300% more of the target protein than unmodified wild-type cells.
Implementation Method 1
at least one recombinant promoter operably linked to at least one gene encoding a polypeptide or protein supporting the biosynthesis of polypeptides or proteins within said cell
Implementation Method 2
significantly increases the production of recombinant proteins by minimizing metabolic interference and ensuring consistent expression levels, resulting in higher yields
Data Source
AI summary
The present invention relates to a genetically modified yeast cell comprising: —at least one recombinant promoter operably linked to at least one gene encoding a polypeptide or protein supporting the biosynthesis of polypeptides or proteins within said cell, said at least one gene being located at the native genomic locus of the genetically unmodified wild-type yeast cell, wherein the naturally occurring promoter of the at least one gene encoding the biosynthesis supporting polypeptide or protein is inactivated by at least one mutation within said naturally occurring promoter and, —a secretion cassette comprising a recombinant nucleic acid molecule encoding a protein or polypeptide of interest and a method for producing a recombinant protein or polypeptide of interest using such a cell.