Fermentative Oligosaccharide Production via Sequential Glycosylation
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Solution Overview
Problem
Current methods for producing fucosylated, sialylated, and N-acetyl-glucosaminylated oligosaccharides, particularly human milk oligosaccharides (HMOs) of four or more monosaccharide units, result in complex mixtures due to overglycosylation from diverse glycosyl transferase activities, making efficient production challenging.
Innovation Solution
A method involving genetically modified cells that culture fucosylated, sialylated, or N-acetyl-glucosaminylated lactose trisaccharides as acceptors, using recombinant genes encoding specific glycosyl transferases like β-1,3-galactosyl transferase, α-1,2-fucosyl transferase, and α-2,3-sialyl transferase, to produce HMOs with at least four monosaccharide units by internalizing and glycosylating exogenous acceptors within the cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple types of glycosyl transferases are co-expressed to produce oligosaccharides of four or more monosaccharide units, then the diversity of oligosaccharide structures increases, but complex mixtures of oligosaccharides are formed due to overglycosylation
Solution Approach 1:
The invention divides the glycosylation process into separate sequential steps, with each step performed by a different glycosyl transferase in separate reaction vessels or at different times. This segmentation prevents simultaneous action of multiple enzymes that would otherwise create complex mixtures, while still achieving diverse oligosaccharide structures through controlled sequential glycosylation.
Solution Approach 2:
The invention performs preliminary glycosylation steps to create specific intermediates before introducing subsequent glycosyl transferases. By preparing defined acceptor substrates in advance and controlling the order of enzyme addition, the process achieves structural diversity while maintaining product purity through predetermined reaction pathways.
2Productivity
If different relative activities of different glycosyl transferases are used, then various oligosaccharide intermediates are produced, but overglycosylation occurs leading to complex mixtures
Solution Approach 1:
The invention dynamically controls enzyme activity by adjusting parameters such as enzyme concentration, reaction time, temperature, and pH for each glycosyl transferase step. This dynamic optimization allows high productivity at each stage while precisely controlling the degree of glycosylation to prevent overglycosylation and mixture formation.
Solution Approach 2:
The invention incorporates monitoring and control mechanisms to track the progression of glycosylation reactions. By measuring intermediate product formation and adjusting subsequent enzyme addition or reaction conditions accordingly, the process maintains high productivity while achieving precise control over the final oligosaccharide structure and preventing overglycosylation.
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 allows for the efficient production of specific HMOs like difucosyllactose, sialyl-fucosyllactose, and LNnT, avoiding overglycosylation and complex mixtures, by controlling the expression of enzymes and optimizing glycosylation reactions within the cells.
Implementation Method 1
a recombinant E. coli system wherein one or more types of glycosyl transferases originating from viruses or bacteria have been co-expressed to glycosylate exogenously added lactose
Implementation Method 2
Direct fermentative production of HMOs, especially of short chain trisaccharides, has recently become practical
Data Source
AI summary
The application discloses a method for producing an oligosaccharide of at least four monosaccharide units, advantageously an HMO, particularly an HMO of only four monosaccharide units, said method comprising a step of: culturing, in a culture medium containing a fucosylated, sialylated or N-acetyl-glucosaminylated lactose trisaccharide as acceptor, a genetically modified cell having a recombinant gene that encodes an enzyme capable of modifying said acceptor or one of the necessary intermediates in the biosynthetic pathway of the oligosaccharide of at least four monosaccharide units, advantageously an HMO, particularly an HMO of only four monosaccharide units, from said acceptor.