Wed January 15th 2020
16:00 – 17:00
Seminar Synthetic biology for the reconstitution of active systems
Isabella Guido


In many natural systems interactions between biopolymers and motor proteins give rise to interesting emergent behaviour of active matter that is key to processes essential for functional cellular physiology. One example for this kind of self-organisation in biology are rhythmic bending waves generated by cilia and flagella to promote fluid transport or to propel organisms in fluids. It is known that the main contribution to ciliary beating is due to motor proteins called dynein, which drive sliding of microtubule doublets. We investigate their mechanical interaction and emergent behaviour by analysing a minimal synthetic system that was experimentally assembled with two microtubules and few dynein motors. In this system the microtubule pair undergoes cyclic association/dissociation interactions through rhythmic bending. By considering the shearing force produced by the motors when they move along the adjacent microtubule and the finite elasticity of the system, the beating cycle can be described in terms of curvature and dynein-microtubule binding force.
Furthermore, we use synthetic microtubule-motor protein assembling also as a model system for understanding active nematics, fluids consisting of self-organising elongated particles that in-vitro assemble in dynamical structures at length scales several orders of magnitude larger than those of their components. We analysed the behaviour of microtubule networks subjected to the force exerted by the motors that crosslinked the filaments and let them slide against each other. In this way the system evolves toward a flattened and contracted 2D sheet that undergoes a wrinkling instability and subsequently loses order followed by a transition into a 3D active turbulent state. The experimental results are compared with a numerical simulation that confirms the key role of motor proteins in the contraction and extension of the network. These two different studies demonstrate that active synthetic systems exhibit rich behaviour and have the potential to improve our understanding of self-organisation of subcellular structures.
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The 10th Complex Motion in Fluids 2021
Max Planck Gesellschaft
Centre for Scientific Computing