Unilamellar Liposome Membrane Protein Evolution via Nuclease Treatment

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Solution Overview

Problem

Current methods for molecular evolutionary engineering are limited in targeting and improving membrane proteins, as they are primarily designed for soluble proteins and lack efficient techniques for screening and selecting membrane proteins with desired functions.

Innovation Solution

The development of unilamellar liposomes containing DNA or RNA encoding membrane proteins, along with a cell-free protein synthesis system and a nuclease, which are treated to optimize magnesium concentration and composition, enabling the in-vitro evolutionary engineering of membrane proteins and enhancing screening efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional liposome methods are used for molecular evolutionary engineering, then soluble proteins can be improved, but membrane proteins cannot be effectively targeted

Engineering Contradiction:
Improveapplicability to membrane proteinsVSAvoidscreening efficiency for membrane proteins
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent optimizes specific parameters including intraliposomal magnesium concentration (28.32-50 mM) and nuclease treatment conditions to enable effective membrane protein evolution. These parameter changes make the system adaptable to membrane proteins while maintaining reliable screening functionality.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces nucleases as intermediary agents that selectively degrade external DNA while preserving intraliposomal DNA. This intermediary mechanism enables specific targeting and screening of membrane proteins expressed within liposomes, resolving the contradiction between versatility and reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If nuclease treatment is applied to liposomes, then screening efficiency improves, but DNA degradation risk increases

Engineering Contradiction:
Improvescreening efficiencyVSAvoidDNA integrity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent segments the system into intraliposomal and extraliposomal compartments. Nucleases are applied externally to degrade only extraliposomal DNA, while the liposome membrane protects intraliposomal DNA. This segmentation enables high screening efficiency without compromising the integrity of functional DNA.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses DNA within liposomes as protected templates that serve as copies of the genetic information. These intraliposomal DNA copies are shielded from nuclease degradation, allowing screening of membrane protein variants while preserving the genetic material for subsequent analysis.

Inventive Principle:
Principle #26Copying

3Reliability

If magnesium concentration is optimized in liposomes, then membrane protein function improves, but system complexity increases

Engineering Contradiction:
Improvemembrane protein functionVSAvoidliposome composition control
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent establishes specific magnesium concentration ranges (28.32-50 mM) that optimize membrane protein function within liposomes. By defining clear parameter boundaries, the patent manages system complexity while achieving reliable functional outcomes for membrane protein evolution.

Inventive Principle:
Principle #35Parameter changes

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 the effective selection and collection of membrane proteins with desired functions, particularly transporter proteins, by optimizing the liposome composition and magnesium concentration, thereby improving the sensitivity and efficiency of the screening process.

Implementation Method 1

The unilamellar liposome is treated with a nuclease which is selected from the group consisting of a ribonuclease and a deoxyribonuclease

Methodology Applied
Scientific EffectNuclease activity: Enzyme

Implementation Method 2

a cell-free protein synthesis system

Methodology Applied
Scientific EffectProtein synthesis: Enzyme

Data Source

PatentEP2876159B1Molecular engineering method for in vitro evolution of membrane protein
Publication Date: 2019.08.07 THE JAPAN SCI & TECH AGENCY
  • EP2876159B1 patent drawingFigure 1A~1D
  • EP2876159B1 patent drawingFigure 2A~2B
  • EP2876159B1 patent drawingFigure 4

AI summary

The objective of the present invention is to improve the efficiency of screening/selection of a membrane protein in molecular evolutionary engineering (for example, an enzyme evolutionary method). The above-described objective is achieved by providing a unilamellar liposome comprising: (a) a DNA comprising a promoter sequence, a translational initiation sequence, and a sequence encoding a membrane protein; (b) an RNA polymerase; (c) a ribonucleotide; and (d) a cell-free protein synthesis system. In one aspect of the present invention, the membrane protein is a transporter, and the unilamellar liposome further comprises (e) a factor that binds to a ligand transported by the membrane protein.