Circular Permuted Caspase-2 for Specific Tag Cleavage
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Solution Overview
Problem
Current methods for removing protein tags using existing proteases are inefficient, lack specificity, and are costly, making them unsuitable for industrial biotechnology applications, particularly for biopharmaceuticals where a tag-free protein is essential.
Innovation Solution
A modified circularly permuted caspase-2 with improved P1' tolerance is developed, allowing for specific and efficient cleavage of N-terminal tags, generating an authentic N-terminus of recombinant proteins, and is capable of catalytic activity upon dimerization without requiring initiator caspases for activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing proteases (factor Xa, thrombin, TEV, enterokinase) are used for tag removal, then tag cleavage can be achieved, but the process is inefficient, unspecific, costly, and requires special buffer conditions
Solution Approach 1:
The patent modifies caspase-2 by changing its substrate specificity parameters through mutagenesis, enabling it to recognize and cleave a broad range of tags including those with Proline at the P1' position, which traditional proteases cannot process. This parameter change in enzyme specificity directly resolves the contradiction by providing efficient, specific, and cost-effective tag removal without requiring special buffer conditions.
2Ease of manufacture
If protein tags are used to facilitate purification and detection, then protein production is enhanced, but tag removal becomes difficult and complex
Solution Approach 1:
The patent extracts the tag removal function from a complex multi-step process and consolidates it into a single enzymatic reaction using modified caspase-2. By designing tags with specific cleavage sites that are exclusively recognized by this engineered protease, the complex task of tag removal is simplified into one specific enzymatic step, resolving the contradiction between ease of manufacture and process complexity.
Solution Approach 2:
The patent introduces a specialized intermediary enzyme (modified caspase-2) that mediates the tag removal process. This intermediary protease is designed to specifically recognize and cleave tags at defined sites, acting as a controlled intermediary between the fusion protein and the desired tag-free product, thereby simplifying the overall process compared to multiple purification steps.
3Ease of manufacture
If tags are used to stabilize expression and increase solubility, then protein production is improved, but tags alter protein structure and characteristics
Solution Approach 1:
The patent extracts the problematic tag component after it has served its temporary function during protein production. By using modified caspase-2 to specifically cleave tags at defined sites, the tag is completely removed, extracting it from the final protein product. This ensures the protein retains its authentic structure and characteristics without tag-induced alterations, while still benefiting from tag-assisted production during the manufacturing phase.
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 caspase-2 achieves high efficiency and specificity in tag removal, ensuring authentic N-termini formation in recombinant proteins, overcoming the limitations of existing proteases in biotechnological applications.
Implementation Method 1
A modified caspase-2 with improved P1' tolerance is developed, allowing for specific and efficient cleavage of N-terminal tags
Implementation Method 2
MacKenzie and Clark investigated the role of dimerization in the ability of caspases to form fully functional proteases and describe that dimerization is necessary for active site formation because both caspase monomers contribute residues that enable the formation of a fully functional active site
Data Source
AI summary
The invention refers to a single-chain circular permuted caspase-2 comprising the following structure from N- to C-terminus: i) a small subunit of a caspase-2, or a functionally active variant thereof; and ii) a large subunit of a caspase-2, or a functionally active variant thereof, wherein said cp caspase-2 comprises one or more amino acid substitutions increasing P1′ tolerance of said cp caspase-2 compared to a cp caspase-2 without said amino acid substitutions.