A Live-Cell Fluorescence High-Throughput Screening Method for Antimicrobial Peptides Based on the SpyTag/SpyCatcher...

Antimicrobial peptides (AMPs) are key to innate immunity but face challenges in rational design due to their diversity and complex mechanisms. The lack of sensitive and full function-based high-throughput screening methods for AMP variants has further impeded systematic exploration and optimization. To address this, we developed a high-throughput screening method for AMPs integrating SpyTag/SpyCatcher click biology and fluorescence resonance energy transfer (FRET). Attributing to the ultrahigh reaction rate and specificity of the SpyTag/SpyCatcher pair, this screening method allows real-time fluorometric detection of the cell lytic activity of AMPs against their natural targets, i.e., bacterial cells. Applied to an indolicidin proline-scanning library, this approach identified variants with enhanced activity against E. coli and B. subtilis. Collectively, this work establishes a function-based, high-throughput screening platform for AMPs that can fully reflect their functional complexity, thereby providing an efficient and scalable tool for screening AMP libraries and facilitating data-driven optimization and functional analysis.