Regensburg 2013 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 1: Cell migration
BP 1.7: Vortrag
Montag, 11. März 2013, 11:30–11:45, H43
Sensing the surface: shortcuts for bacteria — •Siddharth Deshpande1, Isabelle Hug2, Urs Jenal2, and Thomas Pfohl1 — 1Department of Chemistry, University of Basel, Switzerland — 2Biozentrum, University of Basel, Switzerland
Caulobacter crescentus is an oligotrophic bacterium which divides asymmetrically to generate a sessile stalked cell and a flagellated swarmer cell. While the stalked cell immediately enters the next cell cycle, the swarmer cell remains in G1 phase for a definite time before differentiating into a stalked cell by losing the flagellum, pilli and producing an adhesive organelle, the holdfast. This cell cycle progression is controlled by cyclic di-GMP signaling and associated phosphorylation networks. We have developed a microfluidic assay to show that swarmer cells can attach immediately after the cell division if they encounter a surface during growth, suggesting that the cell cycle program for motile-sessile transition can be overridden when cells mechanically sense the surface.
By controlling the fluid flow in the microchannel, we find that a drag force of about 20 pN is sufficient to induce > 50% of the ‘newborn’ swarmer cells to attach immediately after the division. This surface mediated attachment is strongly dependent on pilli, active flagellum, intact holdfast production and cyclic di-GMP concentration. High speed imaging studies show that swarmer cells, which do not attach immediately, have a tendency to rotate (20−30 Hz) just before they separate from the stalked cell. Immediately attaching swarmers do not rotate but show a directional creeping suggesting surface attachment.