Molecular mechanism of high force generation by bacterial pili

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The development of bacterial biofilms resembles eukaryotic development in various aspects. It was shown that mechanical forces are involved in establishing the tissue architecture of embryos. However, little is known about the role of mechanical forces during biofilm formation. In this project, we will use the type IV pilus (T4P) of Neisseria gonorrhoeae as a tool for controlling force generation between bacteria. During the first project phase we generated mutants that generate different levels of force by T4P retraction. Here, we will use these mutants to address the question how the cell-to-cell interaction forces influence the biofilm local microstructure including the radial distribution function. The influence of interaction forces on the rheological properties of biofilm will be characterized as a function of biofilm age. Moreover, we hypothesize that cell-cell contact and biofilm age affect force generation by bacteria. This hypothesis will be scrutinized by characterizing the intracellular localization and binding kinetics of the pilus retraction ATPase PilT and its antagonist PilF using PALM and single molecule tracking. It is tempting to speculate that the local biofilm structure affects the accessibility of nutrients, oxygen, and antimicrobials. As a long term goal, we will assess how the cell-to-cell interaction force affects the fitness of bacteria within the biofilm under benign conditions and under external stress.