Bacterial Cell Permeabilization for Protein Screening
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Solution Overview
Problem
Current protein display methods, such as phage display and microbial surface display, face challenges with high background noise and low resolution in affinity protein screening, particularly when proteins form insoluble inclusion bodies in bacterial cytoplasm, making it difficult to screen affinity protein and enzyme libraries effectively.
Innovation Solution
A method involving the permeabilization of bacterial cells to retain polypeptides either inside or attached to the cell, allowing for direct contact with target molecules and assessment of desired activities, using detergents like Decanoyl-N-methylglucamide and demithyloctylphosphine oxide to maintain cell integrity and facilitate protein interaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If proteins are expressed in the bacterial cytoplasm at high yield, then production efficiency is improved, but the proteins form insoluble inclusion bodies that require laborious refolding and testing
Solution Approach 1:
The invention extracts the polypeptide from the bacterial cytoplasm and displays it on the bacterial cell surface using fusion proteins with cell wall anchoring domains. This allows the polypeptide to be produced intracellularly at high yield while being presented on the cell surface in a soluble, active state, eliminating the need for refolding procedures.
Solution Approach 2:
The invention uses an intermediary anchoring protein (such as a lipoprotein or cell wall binding domain) that mediates between the intracellularly produced polypeptide and the bacterial cell wall. This intermediary allows the polypeptide to be retained in the cytoplasm for high-yield production while being displayed on the cell surface for screening.
2Measurement precision
If proteins are displayed on the bacterial cell surface, then screening resolution is improved, but the scalability and production efficiency are reduced compared to intracellular expression
Solution Approach 1:
The invention merges the advantages of intracellular expression (high productivity) with surface display (high screening resolution) by creating fusion proteins that combine the polypeptide of interest with cell wall anchoring domains. This allows simultaneous achievement of high-yield production and high-resolution screening.
3Adaptability or versatility
If phage display or surface display methods are used for affinity protein screening, then protein diversity can be screened, but background noise is high and resolution between affinity scales is low
Solution Approach 1:
The invention inverts the traditional display approach by displaying affinity proteins (antibodies) on the bacterial cell surface rather than displaying target antigens. This inversion, combined with intracellular production and detergent permeabilization for controlled release, reduces background noise and improves affinity scale resolution while maintaining the ability to screen diverse protein libraries.
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 enhances the screening efficiency by maintaining protein integrity and allowing for effective binding and enzymatic modification assessment within the bacterial cell, overcoming the limitations of traditional methods by reducing background noise and improving resolution.
Implementation Method 1
permeabilising the bacterial cell with a detergent, thereby allowing a target molecule to diffuse into the permeabilised bacterial cell, but retaining the polypeptide and the coding polynucleotide inside the permeabilised cell
Implementation Method 2
allowing a target molecule to diffuse into the permeabilised bacterial cell
Data Source
AI summary
The present invention relates to methods for screening a polypeptide for desired activity against a target molecule In particular, the present invention relates to methods for screening a polypeptide for desired activity against a target molecule by expressing the polypeptide in a bacterial cell and permeabilizing the cell.