Regensburg 2013 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 5: Cytoskeleton

BP 5.3: Vortrag

Montag, 11. März 2013, 15:45–16:00, H43

The dynamical cytoskeleton regulates morphogenesis in rod-like bacteria — •Sven van Teeffelen — Department for Molecular Biology, Princeton University, Princeton, USA

Bacteria were long regarded as unstructured bags of freely diffusing proteins and DNA. Contrary to this view, bacterial cells are now known to display intricate sub-cellular localization and dynamics of their constituents, which is required for a variety of processes including cellular morphogenesis. Biophysically, one mechanism for achieving macroscopic order relies on the bacterial cytoskeleton. Here we report a quantitative study of the dynamics of the Escherichia coli actin homolog MreB, which is essential for the maintenance of rod-like cell shape in bacteria. We found that MreB rotates around the long axis of the cell in a persistent manner and that this rotation depends on the assembly of the peptidoglycan cell wall. Biophysical modeling suggests that MreB and cell-wall synthesis are physically coupled. Thus, the MreB motion observed constitutes a reporter of the local insertion of cell-wall material. In agreement with recent experiments on macroscopic twisting of the cell envelope during growth we find that peptidoglycan is deposited in the cell wall in a helical manner. The cell wall in turn ultimately determines bacterial cell shape. Semi-atomistic computational simulations suggest that one function of MreB is to ensure a uniform distribution of new peptidoglycan insertion sites, a necessary condition to maintain rod shape during growth. Based on the same computational framework we hypothesize that MreB governs bacterial cell shape in a non-trivial manner.