Circularly Permuted Luciferase Biosensor for Granzyme B Detection
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Solution Overview
Problem
Current methods for measuring cell-mediated cytotoxicity, particularly by cytotoxic lymphocytes and natural killer cells, rely on radioactive assays like the chromium release assay, which are time-intensive and pose health risks, necessitating the development of non-radioactive alternatives for detecting granzyme B activity and cellular processes.
Innovation Solution
The use of modified circularly-permuted thermostable luciferases with linked sensor regions that interact with granzyme B, allowing for enhanced luminescence detection in the presence or absence of the target molecule, enabling non-radioactive assays for cell-mediated cytotoxicity and granzyme B activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radioactive assays like chromium release assay are used to measure cell-mediated cytotoxicity, then detection capability is achieved, but health risks increase and time consumption increases
Solution Approach 1:
The patent replaces the radioactive detection system with a bioluminescence-based detection system. Specifically, it uses a circularly permuted thermostable luciferase (CPL) fused to a sensor peptide that binds to granzyme B. When granzyme B is present and cleaves the sensor peptide, CPL becomes active and produces luminescence upon addition of substrate, enabling detection without radioactive materials.
Solution Approach 2:
The patent introduces an intermediary substance - the circularly permuted thermostable luciferase with sensor peptide - that mediates between the target molecule (granzyme B) and the detection system. The sensor peptide acts as a bridge that specifically binds granzyme B and triggers luminescence, replacing the direct radioactive labeling approach.
2Measurement precision
If radioactive assays like chromium release assay are used to measure cell-mediated cytotoxicity, then detection capability is achieved, but time consumption increases
Solution Approach 1:
The patent employs preliminary action by pre-fusing the circularly permuted thermostable luciferase with the sensor peptide to create a ready-to-use biosensor. This pre-prepared fusion protein can be directly added to samples for immediate detection, eliminating the need for time-consuming radioactive labeling procedures and multiple assay steps.
Solution Approach 2:
The bioluminescence detection system replaces the time-intensive radioactive assay protocol. The luminescent signal is generated rapidly upon addition of substrate to cells expressing the CPL-sensor fusion protein, enabling faster throughput compared to chromium release assays that require incubation and washing steps.
3Object-affected harmful factors
If modified circularly-permuted thermostable luciferases are used for detection, then health risks are reduced, but detection sensitivity may be compromised
Solution Approach 1:
The patent applies parameter changes by modifying the luciferase enzyme through circular permutation and thermostabilization mutations. These modifications alter the enzyme's structural parameters to enable fusion with the sensor peptide while maintaining or enhancing catalytic activity. The thermostable variants show improved resistance to proteolysis and maintained luminescence output, ensuring detection sensitivity is preserved.
Solution Approach 2:
The patent creates a composite molecular structure by fusing the circularly permuted thermostable luciferase with the sensor peptide. This composite biosensor combines the detection capabilities of luciferase with the specific binding affinity of the granzyme B-targeting sensor peptide, achieving both safety (non-radioactive) and sensitivity (specific detection).
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 provides a sensitive, efficient, and non-radioactive method for detecting cell-mediated cytotoxicity and granzyme B activity, facilitating high-throughput screening and reducing health risks associated with radioactive materials.
Implementation Method 1
Luciferases are enzymes that catalyze the oxidation of a substrate (e.g., luciferin or coelenterazine) with the concomitant release of photons of light
Implementation Method 2
The linker comprises a sensor region capable of interacting with a target molecule in a cell
Data Source
AI summary
A polynucleotide encoding a biosensor polypeptide comprising a modified circularly-permuted thermostable luciferase and a linker linking the C-terminal portion of the thermostable luciferase to the N-terminal portion of the thermostable luciferase. The modified circularly-permuted thermostable luciferase is modified relative to a parental circularly-permuted thermostable luciferase. The linker contains a sensor region capable of interacting with a target molecule in a cell. The modified circularly-permuted thermostable luciferase has an enhanced response after interaction of the biosensor with the target molecule relative to the parental circularly-permuted thermostable luciferase in the presence of the target molecule. Alternatively, the modified circularly-permuted thermostable luciferase has an enhanced response after interaction of the biosensor with the target molecule relative to the modified circularly-permuted thermostable luciferase in the absence of the target molecule.