IL-15 Analog C-Terminal Modification for High Expression
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Solution Overview
Problem
Interleukin-15 (IL-15) has low production efficiency, difficult purification, and short half-life, making it challenging for industrialization as a protein drug, particularly due to its low expression levels in both prokaryotes and eukaryotes and its instability.
Innovation Solution
An IL-15 analog is developed with positively charged amino acids added to the C-terminal for enhanced expression in Escherichia Coli, and a fatty acid chain is conjugated to improve stability and half-life through binding to albumin, forming a complex that avoids renal filtration and utilizes the FcRn recycling pathway for long-term efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If natural wild-type IL-15 is used as a protein drug, then it has higher safety and activity, but it has low expression levels in prokaryotes and eukaryotes, difficult purification, and short half-life
Solution Approach 1:
The patent modifies the amino acid sequence of IL-15 by adding positively charged amino acids (arginine, lysine, or histidine) at the C-terminal end to create IL-15 analogs. This parameter change in the protein structure enables significantly higher expression levels in E. coli (up to 20-fold) while maintaining biological activity and safety profiles, thereby resolving the contradiction between reliability and productivity
Solution Approach 2:
The patent creates a composite structure by conjugating the IL-15 analog with a fatty acid chain to form a lipoprotein conjugate. This composite material combines the properties of the protein (biological activity) with the fatty acid chain (membrane association and extended half-life), achieving both high productivity and maintained reliability
2Stability of the object's composition
If natural wild-type IL-15 is used, then it maintains native structure, but it has short half-life and difficult purification
Solution Approach 1:
The patent introduces positively charged amino acids at the C-terminal end of IL-15, which changes the electrostatic parameters of the protein. This modification enhances protein stability and extends half-life in biological systems while maintaining the core structural integrity and disulfide bond configuration necessary for native-like folding and receptor binding
Solution Approach 2:
The conjugation of the IL-15 analog with a fatty acid chain creates a lipoprotein complex that resists renal filtration and extends circulation time. The fatty acid chain anchors the protein to cell membranes, protecting it from degradation and significantly extending half-life while the protein portion maintains its native structural conformation for receptor interaction
3Productivity
If IL-15 is expressed in E. coli, then production efficiency can be improved, but purification becomes more difficult
Solution Approach 1:
The addition of positively charged amino acids at the C-terminal end creates a distinct electrostatic signature in the IL-15 analog that facilitates differential binding to charged resins during purification. This parameter change enables simplified purification through affinity chromatography while maintaining the high expression levels achieved in E. coli
Solution Approach 2:
The fatty acid chain conjugated to the IL-15 analog serves as an intermediary that simplifies purification. The lipoprotein conjugate can be selectively purified based on its amphipathic properties and membrane association characteristics, providing a straightforward purification pathway that maintains the high productivity of E. coli expression
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 IL-15 analog achieves significantly higher expression levels (up to 20-fold) and prolonged efficacy without altering cellular activity, facilitating industrialization and maintaining binding to the IL15Rα receptor for effective signal transduction.
Implementation Method 1
a fatty acid chain is conjugated to improve stability and half-life through binding to albumin, forming a complex that avoids renal filtration and utilizes the FcRn recycling pathway for long-term efficacy
Data Source
Figure 1~2a
Figure 2b~2c
Figure 2d~2e
AI summary
The present application discloses an IL-15 analog. The amino acid sequence of the IL-15 analog comprises the amino acid sequence of IL-15, and one or more amino acids added to the C-terminal of the amino acid sequence of IL-15. The one or more amino acids comprise positively charged amino acids. The present IL-15 analog is highly expressed in Escherichia Coli, wherein the expression level is about 20-fold higher than that of the wild-type IL-15, and there is no significant difference in cell activity in vitro. The present application further discloses a conjugate of the IL-15 analog, which improves the half-life and the long-term efficacy of the IL-15 analog by coupling with the fatty acid chain. The present application lays a foundation for the industrialization of IL-15 protein drugs.