Conformations and sequence determinants in the lipid binding of an adhesive peptide derived from Vibrio cholerae biofilms

TL;DR

This paper explores how a peptide from Vibrio cholerae biofilms sticks to surfaces by changing shape and binding to lipids, offering insights for biofilm removal and adhesive design.

Contribution

The study reveals a lipid-induced β-hairpin conformation in a Vibrio cholerae adhesion peptide and its role in biofilm adhesion.

Findings

A central aromatic-rich motif in the peptide anchors it to lipid bilayers and forms a β-hairpin upon membrane contact.

Peripheral pseudo repeats enhance binding through avidity, working synergistically with the central motif.

The peptide is conserved across several Vibrio species and is sensitive to membrane curvature.

Abstract

Surface adhesion is critical to the survival of pathogenic bacteria both in natural niches and during infections, often via forming matrix-embedded communities called biofilms. Vibrio cholerae, the causal agent of pandemic cholera, is capable of forming biofilms adhering to both biotic and abiotic surfaces and the biofilm lifestyle has been implicated in promoting the survival of V. cholerae both in the natural reservoir and during host colonization. Previously, a 57-amino acid loop in the biofilm-specific adhesin Bap1 (Bap1-57aa) has been identified as a key contributor to the adhesion of V. cholerae biofilms to various surfaces including lipid membranes. However, the mechanism underlying its interaction with lipids, as well as its secondary structures, remain unresolved. Here, we combined biophysical, computational, and genetic approaches to elucidate the molecular mechanism of how this adhesive peptide interacts with lipids and lipid-coated surfaces. We found that a central aromatic-rich motif anchors the peptide to lipid bilayers while peripheral pseudo repeats enhance binding through avidity. Surprisingly, the core motif undergoes a lipid-induced conformational transition into a β-hairpin, enabling robust membrane insertion. We confirmed these findings both in vitro and in the biofilm context. Moreover, we demonstrated that the adhesive peptide can adhere to model host surfaces and is sensitive to membrane curvature. Finally, we show that the biofilm-derived peptide is found in several other Vibrio species, and its sequence is well-conserved. Our results provide molecular insight into biofilm adhesion and may lead to new strategies for targeted biofilm removal, as well as the design of bioinspired underwater adhesives.

Bacteria often form surface-associated, matrix-embedded communities called biofilms, both in nature and during infections. Vibrio cholerae, the pathogen responsible for the pandemic cholera, is known to form biofilms to survive and thrive on a range of surfaces including host membranes. Previously, we discovered that a short peptide sequence containing 57 amino acids within a biofilm-specific adhesin plays a key role in mediating the adhesion of Vibrio cholerae biofilms to various surfaces. Here, we found that this small peptide has a unique central aromatic-rich motif that undergoes a conformational change when it encounters a lipid membrane, forming a β-hairpin to enable robust membrane insertion. Moreover, the peripheral sequence functions synergistically with the core motif to strengthen lipid binding. Finally, we show through bioinformatic analyses that the biofilm-derived peptide is also found in several other Vibrio species. Our findings reveal molecular insights into biofilm adhesion and suggest new strategies for removing biofilms in medical and industrial settings and for designing bio-inspired underwater adhesives.

Figures