Chimeric Polypeptides for Cellulose Hydrolysis and Cellobiose Conversion
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Solution Overview
Problem
The accumulation of cellobiose during cellulose hydrolysis in ethanol production is undesirable as it inhibits enzymes and represents a yield loss, as it is not readily fermented by yeast like glucose.
Innovation Solution
Development of polypeptides with cellobiohydrolase activity, specifically with at least 95% sequence identity to amino acids 26 to 549 of SEQ ID NO: 2, which are used to treat cellulosic materials, facilitating the degradation and conversion of cellulose into fermentable glucose for ethanol production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional cellulose hydrolysis is used, then cellulose degradation occurs, but cellobiose accumulates and inhibits enzymes
Solution Approach 1:
The invention combines endoglucanase, cellobiohydrolase, and beta-glucosidase activities into a single chimeric polypeptide molecule. This merging of multiple enzymatic functions allows the protein to simultaneously perform cellulose breakdown and cellobiose conversion, preventing cellobiose accumulation and its inhibitory effects while maintaining high hydrolysis efficiency.
Solution Approach 2:
The chimeric polypeptide is designed with multiple functional domains that enable it to perform several enzymatic activities: endoglucanase activity for internal cellulose bond cleavage, cellobiohydrolase activity for sequential cellobiose release, and beta-glucosidase activity for cellobiose conversion to glucose. This multi-functionality allows a single protein to address multiple steps in the cellulose degradation pathway.
2Productivity
If more cellulolytic enzymes are added to increase hydrolysis rate, then productivity improves, but enzyme cost and process complexity increase
Solution Approach 1:
Multiple enzymatic activities that would traditionally require separate proteins are merged into a single chimeric polypeptide. This reduces the number of different enzyme components needed in the system, simplifying the overall enzyme composition while maintaining or enhancing hydrolysis productivity through coordinated action of all activities within one molecule.
3Quantity of substance
If cellobiose accumulates during hydrolysis, then substrate availability for fermentation decreases, but complete cellulose conversion is achieved
Solution Approach 1:
The chimeric polypeptide performs preliminary conversion of cellobiose to glucose during the hydrolysis process itself, before the fermentation stage begins. By incorporating beta-glucosidase activity that converts cellobiose to glucose in advance, the system ensures that glucose is already available and ready for immediate fermentation, eliminating the bottleneck that would otherwise limit ethanol yield.
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 polypeptides enhance the hydrolysis of cellulose, reducing the need for excessive cellulolytic enzymes and minimizing cellobiose accumulation, thereby improving ethanol yield and process efficiency.
Implementation Method 1
cellobiohydrolases sequentially release molecules of cellobiose from the ends of the cellulose polymer
Implementation Method 2
polypeptides having cellobiohydrolase activity... enhance the hydrolysis of cellulose
Implementation Method 3
carbohydrate binding modules... used to treat cellulosic materials
Data Source
Figure 1
AI summary
Disclosed herein are polypeptides having cellobiohydrolase activity, catalytic domains, carbohydrate binding modules and polynucleotides encoding the polypeptides, catalytic domains or carbohydrate binding modules. Disclosed herein are nucleic acid constructs, vectors and host cells comprise the polynucleotides as well as their uses, and methods of producing the polypeptides, catalytic domains, carbohydrate binding modules.