Optogenetic Protein Constructs for Reversible Phase Separation
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Solution Overview
Problem
Current methods lack the capability to dynamically modulate intracellular protein interactions for spatiotemporal control of phase transitions within living cells, which is essential for understanding and manipulating membrane-less organelles.
Innovation Solution
Protein constructs with light-sensitive regions and intrinsically disordered protein regions (IDRs) are developed, allowing for reversible liquid-liquid phase separation and control over phase transitions by varying light exposure, enabling the formation of dynamic liquid droplets or arrested gels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light-sensitive protein constructs are used to induce phase separation, then dynamic control of protein clustering is achieved, but the system complexity increases due to the need for light delivery and optical control mechanisms
Solution Approach 1:
The patent replaces mechanical mixing or chemical induction methods with optical control mechanisms. Light-sensitive protein constructs (such as those containing photolyase or phytochrome domains) undergo conformational changes upon light exposure, triggering phase separation without requiring mechanical intervention or complex chemical reagents. This substitution simplifies the overall system while enabling precise spatiotemporal control.
Solution Approach 2:
The patent utilizes changes in physical parameters (light wavelength, intensity, and duration) to control the phase transition state. By varying these optical parameters, the system can transition between different material states (liquid droplets vs. gelated networks) and control the kinetics of protein clustering, providing versatile dynamic control without increasing system complexity.
2Speed
If strong light activation is used to rapidly induce clustering, then the speed of phase transition increases, but the reversibility of the process decreases due to potential irreversible aggregation
Solution Approach 1:
The patent employs periodic or pulsed light activation instead of continuous strong illumination. By applying light in controlled pulses or cycles, the system achieves rapid phase transition during illumination while allowing reversibility during dark intervals. This periodic action enables the system to cycle between clustered and dispersed states, maintaining both speed and reversibility.
Solution Approach 2:
The patent designs protein constructs with dynamic material properties that can switch between liquid-like and gelated states based on light exposure. The intrinsically disordered protein regions (IDRs) and light-sensitive domains work together to create a dynamic system where the material state responds reversibly to optical stimuli, allowing fast transitions without permanent aggregation.
3Stability of the object's composition
If light exposure is continued to maintain clustered state, then the stability of protein clusters increases, but the energy consumption increases due to continuous illumination requirements
Solution Approach 1:
The patent uses preliminary light exposure to induce phase separation and form stable clusters, after which the system can maintain its state without continuous illumination. The light-sensitive protein constructs undergo conformational changes during initial illumination that stabilize the clustered state, reducing or eliminating the need for ongoing energy input to maintain cluster stability.
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 allows for precise control over the material state of phase-separated clusters, from dynamic droplets to irreversible aggregates, facilitating the study and regulation of intracellular phase transitions and protein interactions.
Implementation Method 1
a light sensitive region containing a first segment (e.g., a protein sensitive to at least one wavelength of light)
Implementation Method 2
many of these structures have recently been shown to exhibit additional behaviors typical of condensed liquid phases... analogous to the phase transitions of purified proteins long observed in vitro
Data Source
AI summary
A protein construct including a gene encoding a light-sensitive protein fused to at least one of either a low complexity sequence, an intrinsically disordered protein region (IDR), or a repeating sequence of a linker and another gene encoding a light-sensitive protein. Among the many different possibilities contemplated, the protein construct may also advantageously include cleavage tags. This protein construct may be utilized for a variety of functions, including a method for protein purification, which requires introducing the protein construct into a living cell, and inducing the formation of clusters by irradiating the construct with light. The method may also advantageously include cleaving a target protein from an IDR, and separating the clusters via centrifuge. A kit for practicing in vivo aggregation or liquid-liquid phase separation is also included, the kit including the protein construct and a light source capable of producing a wavelength that the light-sensitive protein will respond to.