Modified Proteins Cytosolic Delivery via Amphipathic Helices
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Solution Overview
Problem
Current methods for delivering peptides and proteins across biological membranes are inefficient, with cationic modifications often getting trapped in endocytic vesicles and failing to access the cytosol or nucleus, and there is a need for improved molecules that can efficiently cross these membranes with low toxicity.
Innovation Solution
Modified proteins with at least 4 cationic residues displayed on 3 α-helical faces, selected from arginine and histidine, are designed to facilitate efficient transport into the cytosol, and can be used as fusion molecules or in conjunction with cargo molecules to deliver therapeutic agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cationic modifications are added to peptides or proteins to facilitate transport across plasma membranes, then cell uptake efficiency is improved, but the molecules get trapped in endocytic vesicles and fail to access the cytosol or nucleus
Solution Approach 1:
The patent applies local quality by creating distinct functional regions within the protein structure: cationic regions for membrane interaction and endocytosis, and hydrophobic regions for endosomal escape. This spatial differentiation of properties allows the protein to perform multiple functions sequentially - first being taken up by cells via endocytosis, then escaping the endosomal compartment to reach the cytosol.
Solution Approach 2:
The patent employs parameter changes by modifying the amphipathic character of the protein - specifically by adjusting the ratio and distribution of cationic to hydrophobic residues. This parameter optimization enables the protein to balance two competing requirements: sufficient cationic charge for efficient endocytosis, and sufficient hydrophobicity for endosomal membrane disruption and cytosolic release.
2Productivity
If high concentrations of cationic proteins are used to achieve cell permeability, then transport efficiency is improved, but membrane disruption and toxicity increase
Solution Approach 1:
The patent uses parameter changes by optimizing the amphipathic ratio - the balance between cationic and hydrophobic residues. By fine-tuning this parameter, the protein achieves sufficient membrane interaction and endocytosis efficiency at lower concentrations, while avoiding excessive membrane disruption and cytotoxicity that would occur at higher concentrations.
Solution Approach 2:
The patent employs an intermediary mechanism where the amphipathic protein acts as a mediator between the extracellular environment and the cytosol. The protein's dual character allows it to interact with endosomal membranes in a controlled manner, facilitating cargo release without causing uncontrolled membrane disruption or cell death.
3Reliability
If endocytosis is blocked to prevent vesicular trapping, then cytosolic access is improved, but cell uptake efficiency decreases
Solution Approach 1:
The patent applies segmentation by dividing the transport process into distinct phases: Phase 1 uses endocytosis for efficient cellular uptake, and Phase 2 uses hydrophobic-mediated endosomal escape for cytosolic access. This segmentation allows each mechanism to perform its optimal function without interfering with the other.
Solution Approach 2:
The patent ensures continuity of useful action by designing a seamless transition from endocytic uptake to endosomal escape. The amphipathic structure enables the protein to continuously progress from the extracellular space, through endocytosis, across the endosomal membrane, and into the cytosol without interruption or trapping at any stage.
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 modified proteins demonstrate enhanced ability to reach the cytosol, achieving higher concentrations and facilitating the delivery of associated cargo molecules, thereby improving therapeutic efficacy with reduced toxicity.
Implementation Method 1
addition of cationic charges to a peptide or protein can aid transport into cells
Data Source
AI summary
This invention is generally related to small proteins, such as miniature proteins, including avian pancreatic polypeptide (aPP), modified so that the small proteins reach the cytosol. In some embodiments, the modified protein molecules deliver an associated cargo molecule to the cytosol. Other embodiments of the invention relate to modified protein fusion molecules that reach the cytosol.