Wanda Kukulski

Membrane architecture and transfer of molecules at contact sites between organelles
Group Leader page

All eukaryotic cells use membranes to spatially organize their numerous intracellular processes. These membranes are not just inert barriers. They are compositionally and morphologically dynamic, and their shape and topology are intimately tied to organelle function. Essential processes such as endocytosis, intracellular transport, and inter-organelle communication are all dependent on properly regulating membrane architecture. Conversely, defects in membrane architecture of different organelles have been linked to various human diseases. Yet, the mechanisms that couple membrane architecture to associated cellular functions are poorly understood and challenging to study.

We address these topics by combining state-of-the-art microscopy at multiple scales of resolution, ranging from fluorescence imaging of live cells to electron cryo-microscopy of cellular landscapes. We implement novel methods for visualizing the identical structures at both scales, permitting the exploration of rare or transient events, and identifying elusive structures. In particular, using fluorescence microscopy we first localise proteins that are fluorescently labelled. We then use electron cryo-tomography to visualise the cellular structures adopted by these proteins.

A current focus of the group is the membrane architecture at contact sites between two organelles. Organelle contact sites are important for communication and exchange of molecules such as Calcium, lipids and metabolites. Special proteins localised at contact sites accomplish these molecular transfer reactions and mediate the tethering of the two organelles. We aim at visualising and understanding the structural organisation of proteins at interfaces between organelles. By studying the architecture of membrane contact sites, we want to shed light on the mechanism and regulation of molecular transfer reactions between organelles. Possible PhD projects on this topic will be discussed during the interviews. The eventual project outline will depend on personal interest and background of the candidate, and will combine cell biology, molecular genetics and biochemistry with fluorescence and electron microscopy as well as image analysis


References

Bharat, T.A.M., Hoffmann, P.C. and Kukulski, W. (2018)
Correlative microscopy of vitreous sections provides insights into BAR-domain organization in situ.
Structure. 26879-886.

Hoffmann, P.C. and Kukulski, W. (2017)
Perspective on architecture and assembly of membrane contact sites.
Biol Cell. 109, 400-408.

Mahamid, J., Pfeffer, S., Schaffer, M., Villa, E., Danev, R., Cuellar, L.K., Forster, F., Hyman, A.A., Plitzko, J.M., Baumeister, W. (2016).
Visualizing the molecular sociology at the HeLa cell nuclear periphery.
Science 351, 969-972.

Kukulski, W., Schorb, M., Welsch, S., Picco, A., Kaksonen, M., and Briggs, J.A. (2011)
Correlated fluorescence and 3D electron microscopy with high sensitivity and spatial precision.
J. Cell Biol. 192, 111-119.