Berlin 2008 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 12: Cellular Force Generation

BP 12.5: Vortrag

Dienstag, 26. Februar 2008, 18:30–18:45, C 243

Interaction with host cells influences bacterial pilus dynamics — •Dirk Opitz and Berenike Maier — WWU Münster, Institut für Allgemeine Zoologie und Genetik, Schloßplatz 5, 48149 Münster, Germany

The human pathogen Neisseria gonorrhoeae generates force in the range of 100pN. The force generating machine is the type IV pilus, a polymeric cell appendage that generates force by retracting into the cell body. Eucaryotic cells can sense mechanical force and respond by cytoskeletal rearrangements. We therefore hypothesize that force generated by pilus retraction is a signal to their epithelial host cell which may facilitate phagocytosis. Vice versa, products of activated signalling pathways upregulate the expression level of the putative pilus retraction motor PilT. Here, we investigated the dynamics and force generation by individual type IV pili using laser tweezers between 3h and 24h after infection of epithelial cells was initiated. We found that the velocity at forces below 50pN decreased from (1.1±0.1)µm/s in abiotic environment to (0.7±0.1)µm/s. Bacteria generated considerable force during infection but the maximum force was reduced from (125±36)pN in abiotic environment to (73±25)pN on epithelial cells independent of infection time. The type IV pilus dynamics in abiotic environment and on host cells is significantly different suggesting that the signalling between pathogen and host cell is bidirectional.