Cytoplasmic Protein Complex for High-Sensitivity Interaction Detection
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Solution Overview
Problem
Current methods for detecting protein-protein interactions, especially modification-dependent interactions under physiological conditions, face challenges such as low sensitivity, high background noise, and inability to detect nuclear interactions effectively.
Innovation Solution
A cytoplasmic protein complex comprising a recombinant fusion protein with a constitutive mutant kinase and a reporter phosphorylation site, allowing for the detection of protein-protein interactions with high sensitivity and specificity by phosphorylating a reporter site upon interaction, thereby reducing background noise and enabling the detection of weak interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods like co-purification or co-immunoprecipitation are used to detect protein-protein interactions, then the detection can be performed, but the process is tedious and does not allow high throughput screening
Solution Approach 1:
The patent replaces conventional mechanical/biochemical methods (co-purification, co-immunoprecipitation) with a fluorescent resonance energy transfer (FRET) based optical detection system. This substitution enables high-throughput screening by allowing automated fluorescent signal measurement without tedious manual processing steps
Solution Approach 2:
The invention utilizes fluorescent color changes as a readout mechanism for detecting protein-protein interactions. The FRET signal changes (fluorescent emission intensity and wavelength shifts) provide a quantitative, easily measurable indicator that can be processed in high-throughput formats
2Reliability
If conventional methods are used to detect protein-protein interactions, then interactions can be identified, but the normal cellular context is corrupted due to required lysis
Solution Approach 1:
The patent replaces cell lysis with a non-destructive optical detection method. FRET can be measured in live cells or intact cell lysates without requiring complete cell disruption, thereby preserving the physiological context and native protein environments during interaction detection
Solution Approach 2:
The FRET-based system allows detection of protein interactions in their native cellular environment without external intervention that would disrupt cellular integrity. The fluorescent probes themselves serve as the detection mechanism within the living system, eliminating the need for destructive sampling
3Adaptability or versatility
If yeast two-hybrid system is used to detect protein-protein interactions, then genetic approaches become available, but fusion proteins need to be translocated to the nucleus which is not always evident and may cause false positives
Solution Approach 1:
The patent replaces the yeast nuclear translocation mechanism with a cytoplasmic or membrane-proximity FRET detection system. By using fluorescently labeled proteins that remain in their native cellular compartments, the method eliminates false positives arising from artificial nuclear localization while maintaining genetic detection capabilities
Solution Approach 2:
The FRET signal acts as an intermediary readout that directly reports protein-protein interactions without requiring translocation to a specific cellular compartment. The energy transfer between fluorescent probes provides a direct measure of molecular proximity and interaction, independent of nuclear-cytoplasmic transport
4Adaptability or versatility
If conventional methods are used to detect protein-protein interactions, then general interactions can be detected, but modification-dependent interactions such as phosphorylation cannot be easily detected
Solution Approach 1:
The patent employs fluorescent probes with distinct emission spectra that change based on their binding state or post-translational modification status. FRET efficiency changes or wavelength shifts provide sensitive readouts of modification-dependent interactions, enabling detection of phosphorylation events and other protein modifications
Solution Approach 2:
The invention utilizes changes in fluorescent parameters (intensity, wavelength, lifetime) as readouts for protein modification states. By monitoring FRET signal parameters, the system can detect subtle conformational changes and interaction events associated with post-translational modifications with high sensitivity
5Reliability
If phage display approach is used to detect protein-protein interactions, then nuclear translocation is avoided, but proteins are exposed at the phage surface in a non-physiological environment and competition between phages results in selection of only high affinity binders
Solution Approach 1:
The patent replaces phage surface display with intracellular fluorescent protein expression and FRET detection. This substitution allows proteins to interact in their native cellular environment while maintaining the ability to detect weak interactions through sensitive optical measurement, avoiding the artificial selection pressure of phage competition
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
The approach provides a high signal-to-noise ratio, enabling the detection of weak protein interactions that cannot be detected by existing methods, including nuclear interactions, with minimal background interference.
Implementation Method 1
a first recombinant fusion protein comprising a kinase, fused to a first interaction polypeptide and (b) a second recombinant fusion protein comprising a domain comprising a reporter phosphorylation site
Data Source
AI summary
The disclosure relates to a cytoplasmic protein complex comprising: (a) a first recombinant fusion protein comprising a kinase, fused to a first interaction polypeptide; and (b) a second recombinant fusion protein comprising a domain comprising a reporter phosphorylation site, whereby the domain is fused to a second interaction polypeptide. The disclosure relates further to a method to detect compound-compound-interaction using the cytoplasmic protein complex, and to cells comprising such cytoplasmic protein complex.