Casein Fusion Protein Expression via Hydrophilic Peptide Linkage
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Solution Overview
Problem
Current methods for producing milk proteins, particularly caseins, through recombinant DNA expression in heterologous hosts are not economically viable for α-S1, α-S2, and β-caseins, as established strategies like strong promoters and multiple DNA insertions are not effective for these proteins.
Innovation Solution
A recombinant fusion protein is created by combining caseins (α-S1, α-S2, or β-casein) with a caseinomacropeptide (CMP) or its fragment, which increases the hydrophilicity of the protein, improving expression yields by reducing hydrophobicity and enhancing solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If strong promoters or multiple copies of recombinant DNA are used, then expression levels of κ-casein are improved, but expression levels of α-S1 casein, α-S2 casein and β-casein remain low
Solution Approach 1:
The invention uses κ-casein as an intermediary component to create fusion proteins with α-S1, α-S2, or β-casein. The κ-casein portion of the fusion protein contains sequences that are recognized by the host cell's secretion and expression machinery, thereby mediating improved expression and secretion of the otherwise poorly expressed casein variants through the fusion construct.
2Ease of manufacture
If caseins are expressed alone, then the protein structure is simple, but solubility and expression yield are poor due to hydrophobicity
Solution Approach 1:
The invention creates composite fusion proteins by combining hydrophobic casein sequences with hydrophilic κ-casein sequences. This composite structure integrates the functional properties of both components: the target casein structure with the solubility-enhancing and secretion-facilitating properties of κ-casein, thereby improving expression yield and solubility while maintaining the ability to produce the desired casein variant.
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 recombinant fusion protein approach significantly increases the expression levels of caseins, making the production process more sustainable and economically viable by improving protein solubility and yield in heterologous systems.
Implementation Method 1
The peptide may increase the hydrophilicity of the recombinant fusion protein relative to the hydrophilicity of the casein alone. In other words, the peptide may decrease the hydrophobicity of the recombinant fusion protein relative to the hydrophobicity of the casein alone.
Data Source
Figure 1~2b
Figure 3~4
AI summary
A recombinant fusion protein is provided comprises (a) a casein selected from α-S1 casein, α-S2 casein and β-casein; and (b) a peptide comprising a caseinomacropeptide (CMP), or a fragment thereof. The recombinant fusion protein may be produced by culturing a host cell comprising a nucleic acid encoding the protein. The recombinant fusion protein finds use in the production of a recombinant casein and food compositions comprising casein.