Step-function channelrhodopsins for prolonged cell depolarization
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Solution Overview
Problem
Existing light-activated ion channels have limitations due to restricted activation by specific wavelengths of light, localization, and functional speed, which restricts their applicability in controlling cell membrane ion permeability and cell function.
Innovation Solution
Development of light-activated ion channel polypeptides with specific amino acid sequences, such as those provided in SEQ ID NOs: 1, 11, 12, 14, 15, 17, and 18, or their functional variants, which can be activated by blue and green light, maintaining the open state for a statistically significant longer time period compared to control channels, and expressed in cell membranes of excitable cells like neuronal, cardiac, and visual system cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light-activated ion channels are activated by specific wavelengths of light, then activation specificity is improved, but activation versatility deteriorates
Solution Approach 1:
The patent describes channelrhodopsin variants that can be activated by multiple wavelengths of light (blue, green, and yellow wavelengths), allowing a single channel type to respond to different light stimuli. This multi-wavelength activation capability enables versatile control of cell membrane ion permeability while maintaining specific activation characteristics for each wavelength, thus resolving the contradiction between activation specificity and versatility
2Duration of action of moving object
If light exposure duration is extended to maintain channel activation, then activation duration is improved, but harmful effects increase
Solution Approach 1:
The patent describes channelrhodopsin variants with modified ion channel open-state time periods that allow the channel to remain open longer after brief light exposure. This dynamic modification of channel kinetics enables prolonged activation duration without requiring extended light exposure, thereby reducing harmful effects associated with prolonged light illumination while maintaining effective cell activation
Solution Approach 2:
The patent involves pre-modifying the channelrhodopsin amino acid sequence to create variants with inherently longer open-state times before light exposure. This preliminary structural modification prepares the channel to maintain activation longer without continuous light stimulation, allowing brief light pulses to achieve sustained effects and reduce overall light exposure requirements
3Speed
If functional speed of ion channels is increased, then response speed is improved, but activation duration deteriorates
Solution Approach 1:
The patent describes changing the amino acid sequence parameters of channelrhodopsin to create variants with modified kinetic properties. By specifically altering amino acid residues that affect channel gating dynamics, the invention achieves variants that maintain rapid response speeds while simultaneously extending the open-state duration, thus resolving the contradiction between response speed and activation duration through precise parameter modification
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
These polypeptides effectively alter ion conductivity and depolarize cells, enabling prolonged activation with lower light exposure, enhancing responsiveness and reducing negative effects associated with prolonged light exposure, thus offering improved control over cell activity.
Implementation Method 1
activating the ion channel comprises contacting the ion channel polypeptide with one or more of a wavelength of a blue and a wavelength of a green light
Data Source
AI summary
The invention, in some aspects relates to light-activated ion channel molecules and methods for their use to alter cell activity and function. Light-activated ion channel molecules of the invention can be administered to subjects, expressed in cells, and activated with light, to alter membrane potential in the cells, and can be used in methods for assaying compounds, treating diseases and conditions, compound screening and more.