# Features and mechanism of localized enzyme-assisted self-assembly of peptides from unilamellar vesicles

## TL;DR

Scientists studied how enzymes help peptides form nanofibers near cell-like structures, revealing how this process changes membrane shape and permeability.

## Contribution

The study introduces a detailed mechanism of enzyme-assisted peptide self-assembly near vesicles and its effects on membrane deformation.

## Key findings

- Peptide nanofibers form near vesicles and cause transient membrane permeability without destroying the vesicles.
- Cryo-TEM reveals a lag phase before rapid nanofiber formation around SUVs.
- Molecular dynamics simulations explain how nanofibers deform vesicles through mechanical forces.

## Abstract

Localized enzyme-assisted self-assembly (LEASA) has emerged as a powerful tool to generate peptide nanofibers from and within bacteria or cancer cell lines. This approach has led to promising developments in medical imaging, antimicrobial treatments and cancer therapies. Despite these achievements, the features of self-assembly processes localized near the plasma cell membranes and induced by enzymes are not easy to study since biological media compositions are complex and vary over time. From model systems based on giant and small unilamellar vesicles (GUV and SUV respectively) displaying phosphatases at the outer edge of their phospholipid’s membrane, we study the self-assembly of peptides triggered by an enzymatic dephosphorylation. Peptide nanofibers, generated in the close vicinity of GUVs, adsorb all around the membrane where enzymes are located. This process induces the formation of a transient permeability through the membrane without destroying the vesicles, as observed by confocal laser scanning microscopy (CLSM). A cryo-transmission electron microscopy (cryo-TEM) monitoring over time highlights a lag-time before the formation of nano-aggregates located all around SUVs, followed by a rapid formation of short nanofibers near or directly from vesicles. Thanks to the presence of enzymes located on the surface of the vesicles, the micrometer-long nanofibers both adhere and exert such a mechanical force on the spherical shape of vesicles that they deform them. Finally, based on classical molecular dynamics simulations, we propose a mechanism that accounts for all our experimental observations, rationalizing the LEASA process induced on the surface of phospholipid bilayers containing phosphatases.