Visualization and characterization of individual type III protein secretion machines in live bacteria

• DOI: 10.1073/pnas.1705823114
• Publication Date: 2017-05-23T00:40:47Z
• Authors: Yongdeng Zhang; María Lara-Tejero; Jörg Bewersdorf; Jorge E. Galán
• Keywords: Models, Molecular; Salmonella typhimurium; Protein Transport; 0303 health sciences; 03 medical and health sciences; Bacteria; Bacterial Proteins; Type III Secretion Systems; Cluster Analysis; Bacterial Secretion Systems; Single Molecule Imaging

Significance Type III protein secretion systems are essential virulence factors for many bacterial pathogens. Cryo-electron microscopy has provided important details about the architecture and molecular organization of the type III secretion machine in isolation or in fixed samples. However, little information is available about the organization of the type III secretion machine and its individual substructures in live bacteria. Using 2D and 3D single-molecule switching superresolution microscopy, we have visualized individual type III secretion machines in live bacteria and obtained unique insight into the assembly and function of these machines. These studies bridge a major resolution gap in the visualization of type III secretion machines and may serve as a paradigm for the examination of other bacterially encoded molecular machines.