Engineered Yeast Co-Expression for High-Level Human Serum Albumin

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Solution Overview

Problem

Existing methods for recombinant human serum albumin (rHSA) production in yeast suffer from low expression levels, long fermentation times, and high production costs, with Pichia-based systems being prone to contamination and protein degradation.

Innovation Solution

Co-expression of human serum albumin and one or more rHSA expression promoting factors, such as transcriptional activator HAC1, binding protein KAR2, protein disulfide isomerase (PDI), endoplasmic reticulum oxidoreductase (ERO1), and peptidyl-prolyl cis-trans isomerase (PPI), in a yeast host cell, particularly Pichia pastoris, to enhance rHSA expression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional yeast expression systems are used for rHSA production, then the system is well-established and can perform post-translational modification, but the fermentation time is long and production efficiency is low

Engineering Contradiction:

Improveproduction efficiencyVSAvoidfermentation time

Core Design Contradiction:

ProductivityVSDuration of action of moving object

Solution Approach 1:

The patent introduces expression-promoting factors (such as PDI, ERO1, PPI, KAR2, HAC1) into the yeast host cell before rHSA expression begins. These factors are pre-positioned in the endoplasmic reticulum to facilitate rapid protein folding and secretion, eliminating the need for lengthy adaptation periods and reducing overall fermentation time while maintaining high production efficiency

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs expression-promoting factors as intermediary substances that mediate between the rHSA gene expression and the cellular machinery. These factors (PDI, ERO1, PPI, etc.) act as catalysts that accelerate protein folding, disulfide bond formation, and secretion processes, thereby shortening fermentation time without compromising productivity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If Pichia-based systems are used for rHSA expression, then post-translational modification and secretion functions are available, but the system is prone to contamination and protein degradation

Engineering Contradiction:

Improveprotein secretion capabilityVSAvoidcontamination resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces protective factors (such as PDI, ERO1, PPI) into the yeast cell before rHSA expression begins. These factors create a protective environment in the endoplasmic reticulum that prevents protein degradation and contamination during the expression process, thereby enhancing reliability while maintaining secretion capability

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent employs expression-promoting factors as intermediary substances that mediate between the rHSA protein and the cellular environment. These factors act as protective intermediaries that prevent direct contact between the protein and degradation pathways, thereby reducing contamination and protein degradation while maintaining ease of manufacture

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If expression-promoting factors are co-expressed with rHSA, then expression level increases significantly, but the system complexity increases

Engineering Contradiction:

ImproverHSA expression levelVSAvoidgene expression system complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent merges multiple expression-promoting factors (PDI, ERO1, PPI, KAR2, HAC1) into a single integrated expression system. These factors are co-expressed together in the yeast host cell, creating a synergistic effect that significantly increases rHSA expression level while the factors work together as a coordinated system rather than independent complex components

Inventive Principle:

Principle #5Merging (Combining)

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

Significantly increases rHSA expression levels up to 18.2 g/L of fermentation supernatant, reducing fermentation time and laying a foundation for large-scale industrial production.

Implementation Method 1

Endoplasmic reticulum (ER) of yeast is an important site for protein folding into natural conformation and post-modification such as glycosylation and phosphorylation

Methodology Applied

Scientific EffectProtein folding: Folding

Implementation Method 2

Pichia has a post-translational modification function for eukaryotic proteins, so that foreign proteins can be correctly folded, assembled and secreted extracellularly after expression

Methodology Applied

Scientific EffectPost-translational modification:

Implementation Method 3

Pichia can effectively utilize methanol as a single carbon source for high-density fermentation

Methodology Applied

Scientific EffectFermentation: Fermentation

Data Source

PatentUS12454566B2Construction of engineering bacteria for high expression of recombinant human serum albumin

Publication Date: 2025.10.28 SHENZHEN PROTGEN LTD

AI summary

Provided is a method for the high expression of a recombinant human serum albumin, characterized in comprising the step of co-expressing: (a) a human serum albumin gene, and (b) one or more rHSA expression promoting factor genes in a yeast host cell.