Using T7 phage display to select GFP-based binders

Area of Science:

• Biotechnology
• Molecular Biology
• Protein Engineering

Background:

• Traditional phage display is inefficient for cytoplasmic proteins.
• Filamentous phage have limitations in displaying intracellular proteins effectively.

Purpose of the Study:

• To evaluate T7 phage as a platform for displaying cytoplasmic proteins, specifically green fluorescent protein (GFP) variants.
• To develop and select specific GFP-based affinity reagents using T7 phage display for sensitive detection applications.

Main Methods:

• Utilized T7 phage display to present GFP derivatives with binding loops.
• Employed single-molecule detection techniques (fluorescence correlation spectroscopy, anti-bunching) to quantify displayed proteins.
• Optimized selection conditions using mixtures of binders and non-binders.
• Screened a library of T7-displayed GFP clones with CDR3 antibody binding loops.

Main Results:

• Demonstrated successful display of 1-3 GFP molecules per T7 phage particle.
• Optimized selection strategies for isolating specific binders.
• Selected GFP-based binders capable of target recognition.
• Validated the use of selected binders in flow cytometry, fluorescence-linked immunosorbant assays, and immunoblotting without secondary reagents.

Conclusions:

• T7 phage display is an effective system for presenting cytoplasmic proteins like GFP.
• Selected GFP-based affinity reagents offer intrinsic fluorescence detection capabilities.
• This approach enables sensitive detection in various biological assays, reducing the need for secondary labeling.