Berlin 2012 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 16: Molecular Motors
BP 16.3: Vortrag
Mittwoch, 28. März 2012, 16:00–16:15, H 1028
Forces and Fast Dynamics of Gliding Motors in Myxococcus Xanthus — •Fabian Czerwinski1, Mingzhai Sun1, Tam Mignot2, and Joshua Shaevitz1 — 1Institute for Integrative Genomics, Princeton University, USA — 2CNRS, Marseille, France
The gram-negative bacterium Myxococcus xanthus is an important model organism for studies of multicellular grouping as well as biofilm formation. Individual cells use a combination of twitching and gliding motility to form large, multicellular structures. We identified a new class of molecular motors that power gliding motility [1]. These motors, made of the AglQRS proteins, assemble within focal adhesion sites that link the bacterial cytoskeleton to the extracellular surroundings [2].
Our goal is to understand control and cooperativity of these motor complexes within single cells. For this purpose, we combined optical tweezers, fluorescence microscopy, and real-time tracking of attached marker beads. This allows us to assess the step-like activity of motors embedded in the adhesion complexes at high temporal and spacial resolution. We found motor function correlated to the helical pitch of the bacterial cytoskeleton. We further measured motor stalling forces and the time delay between single motor responses to various cell-motility regulators. Measurements of the gliding force of whole cells will complement our results. Our experiments quantitatively explain how the AglRQS motors drive cell gliding and the formation of multicellular structures.
[1] Sun et al., PNAS(108)7559, 2011. [2] Mignot et al., Science(315)853, 2007.