Regensburg 2013 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 5: Cytoskeleton
BP 5.4: Vortrag
Montag, 11. März 2013, 16:00–16:15, H43
Super-resolution imaging of dynamic MreB filaments in B. Subtilis - a multiple motor driven transport? — Philipp von Olshausen1,2 and •Alexander Rohrbach1,2 — 1Lab for Bio- and Nano-Photonics, University of Freiburg, Georges-Koehler-Allee 102, 79110 Freiburg, Germany — 2Centre for Biological Signalling Studies (bioss), University of Freiburg
The cytoskeletal protein MreB is an essential component of the bacterial cell shape generation system. By a super-resolution variant of total internal reflection microscopy using structured illumination and by 3D stacks of deconvolved epi-fluorescence microscopy, we found that inside live Bacillus subtilis cells MreB forms filamentous structures of variable lengths, typically not longer than one micrometer. These filaments move mainly perpendicular to the long bacterial axis revealing a maximum velocity at an intermediate length and a decreasing velocity with increasing filament length. Filaments move along straight trajectories, but can reverse or alter their direction of propagation. Based on our measurements, we provide a model being able to explain all observations. In this model MreB filaments mechanically couple several motors that putatively synthesize the cell wall, whereas the filaments traces mirror the trajectories of the motors. Based on this idea, we developed a mathematical model that can explain the non-linear velocity length dependence. We deduce that the coupling of cell wall synthesis motors determines the MreB filament transport velocity, whereas the filament mechanically controls a concerted synthesis of parallel peptidoglycan (PG) strands to improve cell wall stability.