Engineered Phage Display Platform for Cell-Penetrating Peptide Discovery
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Solution Overview
Problem
Current methods for discovering and measuring cell-penetrating peptides (CPPs) are hindered by poor uptake efficiency, endosomal trapping, and confounding effects of dyes and tags, making it difficult to identify true CPPs for therapeutic applications.
Innovation Solution
An engineered phage-based CPP discovery platform that utilizes modified M13 bacteriophages with cathepsin-cleaving substrates in glycine/serine-rich linkers of protein III, allowing for the identification of novel CPPs with improved cytosolic uptake efficiency and reduced lysosomal localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current CPP discovery methods using dyes and tags are employed, then cellular uptake can be measured, but confounding effects of conjugated dyes and tags interfere with accurate identification of true CPPs
Solution Approach 1:
The patent removes dyes and tags from the CPP discovery system entirely, using instead a dye-free phage display approach where phage particles themselves serve as the cargo. This extraction of harmful elements eliminates the confounding effects while maintaining measurement capability through phage infectivity assays.
2Productivity
If traditional CPP discovery methods are used, then some CPPs can be identified, but poor uptake efficiency and endosomal trapping prevent identification of true CPPs with cytosolic delivery capability
Solution Approach 1:
The patent introduces phage particles as intermediaries between CPPs and the measurement system. The phage serves as a mediator that can be tracked through cellular uptake, endosomal trafficking, and lysosomal degradation pathways, providing a reliable readout of true CPP performance without requiring direct measurement of the CPP itself.
Solution Approach 2:
The patent changes the measurement parameter from direct CPP detection (using dyes/tags) to phage infectivity detection. This parameter change enables accurate assessment of cytosolic delivery by measuring whether phage remain infectious after cellular exposure, which only occurs if CPPs successfully delivered phage to the cytosol.
3Productivity
If high-throughput screening is implemented, then more CPPs can be discovered, but complex mammalian cell engineering and microscopy requirements increase system complexity
Solution Approach 1:
The patent uses phage particles as simplified copies or proxies for CPP-cargo complexes. Instead of engineering complex mammalian cell lines with fluorescent reporters and using microscopy equipment, the system uses phage display technology with simple infectivity-based readouts, dramatically reducing equipment and procedural complexity while maintaining high-throughput capability.
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 platform enables high-throughput discovery of cell-type-selective CPPs with unique mechanisms of action, achieving enhanced cytosolic localization and avoiding lysosomal degradation, thus facilitating the targeted delivery of therapeutic agents.
Implementation Method 1
the modified pIII loses its ability to infect bacteria after exposure to lysosomal peptidases as the N1 and N2 domains are removed upon lysosomal peptidase digestion
Implementation Method 2
Successful, active transport of therapeutic agents and/or carriers of such therapeutic agents to intracellular targets requires cell membrane translocation
Data Source
AI summary
Engineered bacteriophages are disclosed that include modifications in a pIII surface coat protein, especially in at least one of a GS1 and GS2 linker to include a peptidase recognition amino acid sequence therein. Also disclosed are methods of using such engineered bacteriophage for discovering novel cell penetrating peptides (CPPs). Novel CPPs likewise are disclosed.