Reversibly Switchable Fluorescent Protein Indicators for Neuronal Activity
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Solution Overview
Problem
Existing neuronal activity markers based on photoconvertible fluorescent proteins are permanent and irreversible, limiting their utility in capturing multiple snapshots of activity or comparing different activity profiles within the same sample.
Innovation Solution
Development of reversibly switchable fluorescent protein-based indicators, such as those incorporating calmodulin and a calmodulin-binding peptide, which can be switched between bright and dim states by different wavelengths of light, allowing for reversible detection of calcium and neuronal activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photoconvertible fluorescent protein markers are used to detect neuronal activity, then the markers provide permanent and irreversible indication of activity, but this prevents repeated snapshots and comparison of different activity profiles within the same sample
Solution Approach 1:
The patent applies the dynamics principle by creating a fluorescent protein marker that can dynamically switch between different fluorescent states (ON and OFF) in response to light stimulation. The marker transitions from a permanently active state to a controllable, reversible state, allowing researchers to activate, deactivate, and reactivate the marker multiple times to capture different neuronal activity snapshots within the same sample.
Solution Approach 2:
The patent utilizes parameter changes by altering the fluorescent properties of the protein through photoconversion. The marker's fluorescence intensity and wavelength are changed through exposure to specific wavelengths of light, enabling reversible switching between fluorescent and non-fluorescent states. This parameter modification allows the same marker to provide both permanent recording capability and reversible reset functionality.
2Adaptability or versatility
If reversibly switchable fluorescent protein indicators are developed to enable repeated marking, then multiple activity snapshots can be captured, but the complexity of the indicator system increases
Solution Approach 1:
The patent applies the merging principle by combining multiple functional domains into a single fluorescent indicator protein. The construct integrates a fluorescent protein domain, a calcium-binding domain (such as calmodulin), and a calcium-binding peptide (such as M13), creating a unified molecule that simultaneously provides fluorescence, calcium sensing, and calcium-dependent conformational changes that regulate photoswitching. This integrated design achieves reversible marking capability without requiring multiple separate components.
Solution Approach 2:
The patent implements universality by designing a fluorescent indicator that performs multiple functions: it serves as a calcium sensor, a photoswitchable fluorescent marker, and a conformational reporter all in one protein. The indicator can detect calcium levels, change conformation in response to calcium binding, and undergo reversible photoswitching, providing versatile functionality for neuronal activity monitoring while maintaining a single-molecule architecture.
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 repeated and reversible marking of neuronal activity, providing stable and reliable indicators that can differentiate between stimulated and non-stimulated cells, with the ability to reset the markers for multiple cycles, thus overcoming the limitations of permanent indicators.
Implementation Method 1
fluorescent polypeptides that can be reversibly changed from dim to bright fluorescence by irradiating with different wavelengths of light
Implementation Method 2
reversibly switchable fluorescent protein (rsFP), which can include generally include fluorescent polypeptides that can be reversibly changed from dim to bright fluorescence by irradiating with different wavelengths of light
Data Source
AI summary
Reversibly switchable fluorescent protein-based indicators are disclosed, and can be used as neuronal activity markers. The disclosed reversibly switchable fluorescent protein-based indicators exhibit faster or slower photoswitching the presence or absence of calcium, and depending on the wavelength of light stimulus employed.