The F pilus, a type of conjugative pili, is responsible for playing an essential role in horizontal gene transfer between bacterial cells. Cryo-EM based structural models of the F pilus provide insight into the static structure of this system, but the dynamics of F pilus filaments at the molecular scale are unknown. Importantly, in addition to the protein subunits that comprise the F pilus, the structural models indicate that lipid molecules are also present within the filament architecture (specifically phosphatidylgylcerol (PG) lipids). However, the structural role of lipids within the F pilus also remains unclear. Moreover, due to protein-PG interactions, phospholipids seem to induce stability, as the structure is very resistant to degradation.<br/><br/>In order to investigate the structural response of the F pilus to force and temperature, we take a molecular simulation approach. By analyzing the force-extension profile of F pilus structures we are able to gauge their strength with and without the presence of lipids in steered molecular dynamics simulations. Additionally, we carry out simulations to reveal what role lipids play in protecting the F pilus model from structural distortion at high temperatures. Simulations were implemented using the Amber software. Ultimately, understanding the dynamics of the F pilus structure will help reveal how it can interact with and transport DNA, and thus spread antimicrobial resistance between bacterial cells.

Investigation of F pilus dynamics under force and differing temperature environments using molecular simulation

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