Protein microarray assay for the screening of SH3 domain interactions

Area of Science:

• Molecular Biology
• Biochemistry
• Proteomics

Background:

• Cellular signal transduction analysis relies on mapping protein interaction networks.
• Understanding these interactions offers insights into diseases like cancer and aids therapeutic design.
• Modular domains, such as SH3-domains, are crucial for mediating protein-ligand interactions, often recognizing proline-rich sequences.

Purpose of the Study:

• To develop and optimize a microarray-based screening assay for identifying interactions between target proteins and SH3-domains.
• To evaluate different microarray formats and assay workflows for reliable interaction detection.

Main Methods:

• Evaluation of two microarray formats: reactive silane monolayers and nitrocellulose on glass slides.
• Production and purification of nine representative SH3 domains as GST-fusion proteins.
• Spotting SH3 domains on microarrays and probing with known ligands (HIV-1 Nef protein and human Sam68 protein).
• Detection of ligand binding using a fluorescently labeled antibody against the N-terminal His-tag.

Main Results:

• Nitrocellulose slides yielded the best results for low-density model arrays.
• A straightforward and robust detection method for ligand binding was established.
• The optimized assay demonstrated high reproducibility, adequate signal-to-background and signal-to-noise ratios.
• Quantitative determination of relative binding affinities was achieved.

Conclusions:

• A highly reproducible and robust microarray assay for identifying SH3-domain interactions has been developed.
• The optimized protocol enables quantitative analysis of protein-ligand binding affinities.
• This assay facilitates the systematic characterization of protein interaction networks for disease research and drug development.