Combining Yeast Display and Bacterial Genomic Library for the Unbiased Isolation of Novel Polysaccharide-Binding Peptides

TL;DR

This paper introduces a new method using yeast display and bacterial genomic libraries to find peptides that bind to polysaccharides in bacterial biofilms.

Contribution

The novel approach uses genomic diversity to discover naturally encoded polysaccharide-binding peptides without relying on synthetic libraries.

Findings

21 peptides were identified that bind to two distinct rhamnose-rich polysaccharides.

The peptides adopt α-helical or disordered conformations and rearrange upon binding.

Selected peptides modulate biofilm architecture and bacterial viability in a species-specific way.

Abstract

Here, we present a novel yeast surface display-based platform for the discovery of biofilm-associated exopolysaccharide-binding peptides. Unlike conventional synthetic libraries, our approach utilizes the genomic diversity of Burkholderia multivorans strain C1576 through open-reading frame-filtered genomic fragment libraries, thereby enriching for naturally encoded carbohydrate-binding domains. By iterative fluorescence-activated cell sorting, we identified 21 peptides with confirmed binding to two structurally distinct rhamnose-rich polysaccharides: the exopolysaccharide Epol C1576 and the capsular polysaccharide CPS KpB-1. Biophysical characterization revealed that these peptides adopt predominantly α-helical or disordered conformations and undergo structural rearrangements upon polysaccharide binding. Functional assays demonstrated that selected peptides modulate biofilm architecture and bacterial viability in a species-specific manner, although they do not have a direct bactericidal effect against planktonic cells. This proof-of-concept study establishes yeast surface display as a powerful tool for the discovery of biofilm-targeting peptides and provides a basis for development of novel diagnostics and therapeutics to combat biofilm-associated infections.

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