Probing the strength and stability of wild type and mutated N. gonorrhoeaetype IV pili

Abstract

Neisseria gonorrhoeae (Ng) is a gram negative bacteria that causes the well known disease gonorrhea by infecting the mucus membrane of the reproductive system. One of the structures Ng utilize to interact with the environment are protein based filaments known as type IV pili (t4p). These filaments are dynamically built out of protein subunits called pilin. Pili protrude from the bacterial membrane allowing it to anchor to surfaces and exhibit motion known as twitching motility. Interestingly pili can withstand very large forces while being simultaneously highly flexible. To model the impact of force on these filaments, we utilize steered molecular dynamics (SMD). Using SMD we simulate the extension of Ng t4p filaments under tensile stress, and measure the force necessary to extend the pili. By comparing SMD results with equilibrium simulations we are able to analyze the strength and stability of t4p filaments and to investigate how filament biophysical properties are related to atomistic interactions.