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Updated: Aug 8, 2025

Super-Resolution Imaging of Bacterial Secreted Proteins Using Genetic Code Expansion
Published on: February 10, 2023
Purification of the Transmembrane Polypeptide Channel Complex of the Salmonella Flagellar Type III Secretion System
Miki Kinoshita1, Keiichi Namba1,2,3, Tohru Minamino4
1Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan.
Abstract:
Many motile bacteria employ the flagellar type III secretion system (fT3SS) to build the flagellum on the cell surface. The fT3SS consists of a transmembrane export gate complex, which acts as a proton/protein antiporter that couples proton flow with flagellar protein export, and a cytoplasmic ATPase ring complex, which works as an activator of the export gate complex. Three transmembrane proteins, FliP, FliQ, and FliR, form a core structure of the export gate complex, and this core complex serves as a polypeptide channel that allows flagellar structural subunits to be translocated across the cytoplasmic membrane. Here, we describe the methods for overproduction, solubilization, and purification of the Salmonella FliP/FliQ/FliR complex.
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