Related Experiment Video
Updated: Jul 17, 2025

Investigating Flagella-Driven Motility in Escherichia coli by Applying Three Established Techniques in a Series
Published on: May 10, 2020
A single filament biomechanical study of the enteropathogenic Escherichia coli Type III secretion system reveals a
Moran Elias-Mordechai1, Nofar David2, Sonia Oren2
1Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel. berkovir@bgu.ac.il.
Abstract:
Type III secretion systems (T3SSs) are syringe-like protein complexes used by some of the most harmful bacterial pathogens to infect host cells. While the T3SS filament, a long hollow conduit that bridges between bacteria and host cells, has been characterized structurally, very little is known about its physical properties. These filaments should endure shear and normal stresses imposed by the viscous mucosal flow during infection within the intestinal tract. We used atomic force microscopy (AFM) to probe the longitudinal and radial mechanical response of individual T3SS filaments by pulling on filaments extending directly from bacterial surfaces and later pressing into filaments that were detached from the bacteria. The measured longitudinal elastic moduli were higher by about two orders of magnitude than the radial elastic moduli. These proportions are commensurate with the role of the T3SS filament, which requires horizontal flexibility while maintaining its structural integrity to withstand intense stresses during infection.
Related Concept Videos
Gram-negative Bacterial Protein Secretion Systems
Chemotaxis in E. coli
Fimbriae, Pili, and Axial Filaments
Cytoskeletal Proteins in Bacteria
Bacterial Translocation and Protein Secretion

