Type IV pili (T4P) are biopolymers comprised of many protein subunits called pilin. Although the pilin subunits are not covalently bonded to one another, T4P filaments are very strong and flexible. T4P emanate from the surface of prokaryotic cells and carry out many functions, including biofilm formation, surface adhesion, motility, and infection. Recently, structures for T4P from Escherichia coli, Neisseria meningitidis, Pseudomonas aeruginosa, and Neisseria gonorrhoeae have been obtained. Although the structures of T4P are known, the structural changes that occur at the molecular scale when they are subjected to tensile forces are not well characterized. In order to study the structural changes to these various T4P filaments under force, we carried out steered molecular dynamics (SMD) simulations, using the software Amber18, of each T4P at three different pulling velocities: 1 Å/ns, 5 Å/ns, and 10 Å/ns. We analyzed the changes in secondary structure of pilin subunits, global changes in filament architecture, and calculated the Young’s modulus of each of the different T4P filaments. By drawing comparisons between all four T4P filaments, we are able to obtain a broader picture of T4P dynamics. In particular, we observe elongation of the alpha helix region of pilin subunits in each of these systems, which has been previously attributed to T4P flexibility and strength.

Comparing the elongation mechanism of type IV pili from four different bacteria using molecular dynamics simulations

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.