# Construction and characterization of a nanopore derived from the transmembrane domain of a trimeric autotransporter adhesin

## TL;DR

Researchers created a nanopore from a bacterial protein and characterized its ion channel activity, offering a new tool for biotechnology and studying bacterial secretion.

## Contribution

The first characterization of a nanopore derived from a trimeric autotransporter adhesin secreted by the type Vc secretion system.

## Key findings

- AtaApore exhibited ion channel activity with a median conductance of 0.17 nS.
- Molecular dynamics simulations showed Cl− ion trapping at a constriction formed by R3597 and R3622.
- AtaApore serves as a new scaffold for nanopore engineering and a model for studying the type Vc secretion system.

## Abstract

Bacterial secretion systems (SSs) are increasingly recognized as biological nanopores with potential biotechnological applications. Here, we engineered the transmembrane β-barrel of a trimeric autotransporter adhesin (TAA) secreted by the type Vc SS. The coiled-coil segment that occupies the central lumen of the transmembrane β-barrel of an Acinetobacter TAA, AtaA, was removed to design an open β-barrel pore, termed AtaApore. Polypeptides of AtaApore were produced using a cell-free expression system and reconstituted into lipid membranes. Electrophysiological measurements showed ion channel activity of AtaApore with a median conductance of 0.17 nS. Molecular dynamics simulations revealed ion transport properties, including transient trapping of Cl− ions at a constriction formed by R3597 and R3622. Together, to our knowledge, these results provide the first characterization of a nanopore derived from a TAA secreted by the type Vc SS. AtaApore provides a new scaffold for nanopore engineering and a simplified model for probing the mechanism of the type Vc SS.