Fluorescent Phage Display Vector Using Tat Secretion
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Solution Overview
Problem
Current phage display methods face challenges in detecting and isolating phage particles due to their small size, which limits sensitivity and utility in flow cytometry, and direct fluorescent labeling can disrupt target binding or introduce steric hindrance, while existing techniques lack a genotype-phenotype link for selected phage particles.
Innovation Solution
A vector construct combining the E. coli Tat secretory pathway with a fluorophore-pVIII fusion protein allows for the production of intrinsically fluorescent phage particles, enabling simultaneous display of a protein of interest and fluorescence, and optimizing the fusion protein through randomization and phenotypic screening to enhance signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct fluorescent labeling of phage is used, then detection sensitivity is improved, but target binding capability is disrupted or steric hindrance is introduced
Solution Approach 1:
The invention merges the fluorescent protein sequence directly with the pVIII coat protein sequence to create a fusion protein. This single integrated construct ensures that the fluorescent signal and target binding function are inherently linked, eliminating the need for separate labeling steps that could disrupt binding or introduce steric hindrance.
Solution Approach 2:
The phage particle itself produces the fluorescent signal through the integrated fluorophore-pVIII fusion protein. The system is self-sufficient, requiring no external antibodies or chemical labels for detection, thereby maintaining target binding capability while providing intrinsic fluorescent detection.
2Difficulty of detecting and measuring
If phage particles are made detectable by size in flow cytometry, then direct detection is improved, but phage particle size must be increased which is not feasible
Solution Approach 1:
The invention uses fluorescent proteins that emit light at specific wavelengths when excited, enabling detection of phage particles through fluorescence rather than size. This optical detection method allows standard-sized phage particles to be easily detected and sorted by flow cytometry based on their fluorescent signal.
3Measurement precision
If antibody detection methods are used, then phage particles can be detected, but additional incubation and washing steps are required which reduces selection efficiency
Solution Approach 1:
The phage particle inherently produces its own fluorescent signal through the integrated fluorophore-pVIII fusion protein, eliminating the need for secondary antibody detection steps. This self-detecting system allows for streamlined workflows with fewer incubation and washing steps, thereby improving selection efficiency while maintaining detection capability.
4Reliability
If fluorophore is expressed separately from pVIII protein, then functional display is achieved, but genotype-phenotype link is lost
Solution Approach 1:
The fluorescent protein sequence is merged directly with the pVIII coat protein sequence in a single fusion construct. This ensures that the genotype (the fusion gene) is directly linked to the phenotype (fluorescent phage particles displaying the fusion protein), allowing selected phage to be recovered and their sequences identified without loss of the genotype-phenotype correlation.
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 enables efficient and direct detection of phage particles using fluorescence-based methods, maintains target binding capability, and provides a genotype-phenotype link for selected phage particles, improving the phage display process with enhanced sensitivity and utility.
Implementation Method 1
A vector construct combining the E. coli Tat secretory pathway with a fluorophore-pVIII fusion protein
Implementation Method 2
enables efficient and direct detection of phage particles using fluorescence-based methods
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
The present invention provides a vector construct comprising the following components: (i) a sequence encoding a signal peptide which directs proteins into the Tat secretory pathway; and (ii) a sequence encoding a fluorophore fused to a sequence encoding a pVIII phage coat protein. Nucleic acid molecules comprising components (i) and (ii) are also provided, together with phage particles comprising such vectors or nucleic acid molecules and expressing a fluorophore-pVIII fusion protein on the surface. Methods for producing such fluorescent phage particles are also provided.