Type IV pilus (T4P) filaments are long biological polymers that protrude from the surface of various prokaryotic cells. T4P are composed of many copies of a protein subunit called pilin, and can grow to several micrometers in length. T4P are active in several essential biological functions, including surface adhesion, twitching motility, cell signaling, and biofilm formation. They are known to be both strong and flexible, able to withstand tensile forces 10,000 times the bacterial bodyweight, and stretch three times their original length. A 2017 cryo-electron microscopy model of the T4P of N. gonorrhoeae (Ng T4P) revealed the presence of a previously unresolved “melted” region within the alpha helical domain of the pilin subunits. It has been hypothesized that this disordered region contributes significantly to the filament’s ability to extend under force. However, the molecular rearrangements that occur during the polymorphic transition of a T4P and the mechanical role of the “melted” region in filament extension is not fully understood. Here we investigate the response of Ng T4P filaments to applied force using steered molecular dynamics simulations. The AMBER molecular dynamics software package was used to simulate all-atom models, while the GROMACS software package was used to simulate the GoMARTINI coarse-grained models. Analysis of the extension of T4P filaments reveals structural changes in the systems, and materials characteristics of T4P are also measured directly from simulations.

Investigating the response of N. gonorrhoeae type IV pilus filaments to applied force using molecular dynamics

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.