C-5 Sterol Desaturase Optimization for 7-DHC Production
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing 7-dehydrocholesterol (7-DHC) in yeast cells result in excessive accumulation of side-products like zymosterol and lanosterol, which are toxic and reduce the efficiency of vitamin D3 production, as the sterol desaturase enzymes involved are non-specific, leading to a diverse steryl ester pool.
Innovation Solution
Modification of host cells to express heterologous enzymes with C-5 sterol desaturase activity, specifically increasing the expression of ERG3-homologs to enhance the production of 7-DHC by shifting the ratio of 7-DHC to side-products, such as cholesta-7-enol and lathosterol, through targeted genetic modification and optimization of polynucleotides for improved enzyme activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sterol acyltransferase enzymes are used to store excess sterols in lipid bodies, then sterol accumulation is reduced, but the steryl ester pool becomes diverse including toxic side-products like zymosterol, lanosterol, and lathosterol
Solution Approach 1:
The patent changes the specificity parameter of the sterol acyltransferase enzyme by introducing site-directed mutations (e.g., F592L, G595D, F592L/G595D double mutant) to shift substrate preference from diverse sterols to specifically 7-DHC, thereby producing steryl esters enriched in 7-DHC while reducing toxic side-products
Solution Approach 2:
The patent introduces heterologous sterol acyltransferase genes (ARE1 and ARE2 from Aspergillus oryzae) with modified sequences into yeast cells to replace or supplement the native non-specific enzyme, creating a copy with improved specificity for 7-DHC production
2Productivity
If non-specific sterol desaturase enzymes are used in yeast cells, then 7-DHC production occurs, but side-products like zymosterol and lanosterol accumulate excessively
Solution Approach 1:
The patent modifies the specificity parameter of sterol desaturase enzymes through heterologous expression of ERG3 homologs from different fungal sources (Yarrowia lipolytica, Pichia pastoris, Penicillium roqueforti, Schizosaccharomyces pombe) with varying sequence identities, thereby changing the product distribution towards higher 7-DHC specificity
Solution Approach 2:
The patent creates a composite enzymatic system by combining multiple modified enzymes (modified ERG3 desaturase and modified ARE1/ARE2 sterol acyltransferases) working together in the same yeast cell to achieve synergistic improvement in 7-DHC production and reduced side-products
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
The modified yeast cells achieve a significant increase in 7-DHC production, reaching up to 84% of the total sterols, with a corresponding reduction in side-products, thereby improving the efficiency and specificity of vitamin D3 biosynthesis.
Implementation Method 1
expression of heterologous enzymes having C-5 sterol desaturase activity, which leads to higher productivity of the host cell towards 7-DHC
Data Source
AI summary
The present invention is related to an improved method for production of 7-dehydrocholesterol (7-DHC), an important intermediate towards biotechnological production of vitamin D3 or derivatives/metabolites thereof. The invention features modified host strains expressing enzymes having improved C-5 sterol 5 desaturase activity and their use in a process for production of vitamin D3 or derivatives and/or metabolites thereof.