Reconstitution of septin-mediated actin cortex in vesicles (MEP)

What and Why

Bottom-up biology is a way to understand cellular life by rebuilding it in the context of a synthetic cell. Within this context, a cell-like membrane is a fragile structure that needs to be mechanically reinforced. The actin cortex is a cytoskeletal structure which lends stability to eukaryotic cell surfaces. In addition, this actin cortex can be remodelled to dive membrane deformations in migration and division. The latter is one of the key elements that make unicellular life alive. And as such, is one of the basic building block that we need to construct for our synthetic cells. 

Cytokinesis requires a number of actin-binding proteins: myosin motors, which generate cortical tension, and proteins which anchor the actomyosin structure to the cell membrane to allow whole-cell shape change. In order to translate this process into a synthetic cell division mechanism we need to reduce the amount of proteins that are involved to a minimum. And that is the reason why we are interested in septin.  

Septin, a eukaryotic filament forming protein, has been recently acknowledged as the fourth cytoskeletal component. It is especially interesting for synthetic cell division because septins participate in cell division, and are able to interact with both the cell membrane and actin. In our own lab, we have used septin as an membrane anchor for a reconstituted actin cortex and as actin bundlers.

The Project

In this project, you will investigate the actin-remodelling activity of myosin on septin-bound actin cortices and bundles. First, you will build septin-anchored actin cortices and septin-actin bundles using our standard approaches on top of supported lipid bilayers. Then you will use fluorescence microscopy to characterize the effect of myosin on the septin-actin structures.

Depending on your background, you will develop your skills in protein purification, cell-free cytoskeletal reconstitution, and supported lipid bilayer formation. You will learn how to design assays that use fluorescence microscopy to study the effect of myosin on the mentioned actin-septin structures. There will also be opportunities to collaborate with other group members depending on your interests and the progress of the project, for example encapsulating inside liposomes the septin-actin-myosin structures to study their effect on non-supported lipid bilayers.

Qualifications

You participate in a Master study in physics, chemistry, biology or similar. You must be available for at least 6 months. A longer period is possible and preferable. 

Contact

Gerard Castro-Linares (G.CastroLinares@tudelft.nl), Lucia Baldauf (L.Baldauf@tudelft.nl) and Lennard van Buren (L.vanBuren@tudelft.nl)

Group leader: Gijsje Koenderink (G.H.Koenderink@tudelft.nl).

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