Ruprecht-Karls-Universität Heidelberg
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Pfeffer0318 - Scientist (f/m) / PhD position
Project no:

Project leader:

Project supervisor:
Pfeffer, Stefan
Application deadline:
11. Aug 2018
Start of PhD project:
1. Nov 2018

Project description:

Cryo-EM analysis of co-translational complex assembly
Macromolecular complexes are pivotal for all cellular processes. There is steadily growing evidence that a significant portion of these complexes are assembled while at least one of their subunits is still being synthesized on the ribosome, but no direct structural evidence is available. In particular, it is not known how these processes are coordinated in time and space in the crowded microenvironment of an actively translating polyribosome. We will address the structural basis of co-translational complex assembly using cryo-electron tomography (cryo-ET), an imaging approach that can reveal the three-dimensional arrangement of individual macromolecules at molecular resolution even in crowded native microenvironments.

The central objective of this project will be to study defined polysomal complexes engaged in the synthesis of model substrates known to assemble into homo- or hetero-oligomeric complexes co-translationally. Cryo-ET approaches will be used to visualize these assemblies in both a non-cellular context and in sections of vitrified unperturbed cells obtained using focused ion beam (FIB) milling.
1) Pfeffer, S., Burbaum, L., Unverdorben, P., Pech, M., Chen, Y., Zimmermann, R., Beckmann, R., Förster, F. Structure of the native Sec61 protein-conducting channel. Nat Commun. 2015

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

3) Hrabe, T., Chen, Y., Pfeffer, S., Cuellar, L.K., Mangold, A.V., Förster, F. PyTom: a python-based toolbox for localization of macromolecules in cryo-electron tomograms and subtomogram analysis. J. Struct. Biol. 2012.

4) Brandt, F., Etchells, S.A., Ortiz, J.O., Elcock, A.H., Hartl, F.U., and Baumeister, W. The native 3D organization of bacterial polysomes. Cell. 2009.
Methods that will be used:
High-resolution cryo electron microscopy and tomography approaches; advanced image processing; standard biochemical, molecular and cell biology methods
Cooperation partners:
Various groups at the ZMBH
Personal qualifications:
We are looking for a highly motivated PhD student holding a Master’s degree in life sciences with a strong background in computational biology. Experience in electron microscopy is of advantage, but not required.
Structural biology, cryo-EM, cryo-ET, cryo electron microscopy, ribosome, co-translational protein folding, protein maturation, chaperones