Genetically Encoded Reporter for Synaptic ATP Measurement
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Solution Overview
Problem
Current methods are inadequate for directly measuring ATP concentrations at synaptic terminals, which are crucial for understanding energy homeostasis and are relevant to neurological disorders, due to the small size of synaptic terminals and limitations in existing technologies.
Innovation Solution
A genetically encoded hybrid nucleic acid molecule comprising a luciferase enzyme, a fluorescent protein, and a targeting protein linked in a single reading frame, specifically designed to localize to synaptic vesicles, allowing for direct measurement of ATP levels by chemiluminescence and fluorescence imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If current measurement technologies are used, then ATP concentrations can be measured in large volumes, but they cannot measure ATP at synaptic terminals due to the small size of synaptic terminals
Solution Approach 1:
The measurement system is segmented into two functional components: a luciferase enzyme that binds to ATP and a fluorescent protein that provides optical signal. This segmentation allows the measurement function to be adapted to subcellular volumes while maintaining detectable signal output.
Solution Approach 2:
The patent introduces an intermediary fluorescent protein component that acts as a signal amplifier. The luciferase-ATP interaction produces a measurable fluorescent signal that can be detected at synaptic terminal scales, bridging the gap between molecular binding events and macroscopic detection capabilities.
2Adaptability or versatility
If a genetically encoded reporter system is used, then ATP levels can be measured in living tissue, but the system requires multiple protein components that increase complexity
Solution Approach 1:
The patent merges multiple functional domains into a single genetically encoded reporter construct. The luciferase binding domain and fluorescent protein domain are combined into one polypeptide chain that can be expressed from a single gene, simplifying delivery and expression while maintaining dual functionality for ATP detection and optical signaling.
Solution Approach 2:
The reporter construct is designed with multi-functionality: it serves as both an ATP-binding element (luciferase) and an optical reporter (fluorescent protein). This universal design allows a single construct to perform both the sensing and signaling functions required for in vivo ATP measurement.
3Measurement precision
If ATP measurement is performed at synaptic terminals, then local energy homeostasis can be studied, but the small volume makes detection difficult
Solution Approach 1:
The fluorescent protein serves as an intermediary signal transducer that converts the molecular binding event between luciferase and ATP into an optical signal detectable by standard imaging equipment. This intermediary mechanism overcomes the detection difficulty inherent in measuring molecular concentrations at the subcellular scale.
Solution Approach 2:
The patent utilizes fluorescence emission (color change) as the detection mechanism. The fluorescent protein emits light at a specific wavelength when excited, providing a visual readout that directly correlates with local ATP concentration at synaptic terminals, making detection feasible despite the small measurement volume.
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
Enables precise and localized measurement of ATP concentrations at synaptic terminals, overcoming the limitations of existing methods by providing a quantitative analytical tool for studying synaptic energetics and potentially aiding in the diagnosis and research of neurological disorders.
Implementation Method 1
measuring activity of the luciferase enzyme and determining a ratio of the enzyme activity to the fluorescence
Implementation Method 2
a second region that encodes a reporter fluorescent protein
Data Source
AI summary
An isolated nucleic acid reporter construct, the protein for which it encodes and methods for its use for the in vivo or in vitro measurement of the concentration of a specific biologically important molecule in a subcellular compartment or locale are provided. Certain constructs described are useful in measuring the local concentration of ATP at synapses.