Ruprecht-Karls-Universitšt Heidelberg






Open Positions

Project Title: Structure-function analysis of J-domain cochaperones

Project leader: Matthias P. Mayer
Application Deadline: until position is filled
Start of PhD project: as soon as possible
Source of Funding: University of Heidelberg

Project Description: In the center of this PhD project is the molecular mechanism of the Hsp70 chaperone machinery. Hsp70 chaperones are central hubs of the protein quality control network and work in collaboration with J-domain cochaperones and nucleotide exchange factors to facilitate a wide variety of protein folding processes and so (re)establish protein homeostasis. The Hsp70s are highly dynamic nanomachines that modulate the conformation of their substrate polypeptides by transiently binding to short, mostly hydrophobic stretches. This interaction is regulated by an intricate allosteric mechanism. The J-domain cochaperones target Hsp70 to their polypeptide substrates, and the nucleotide exchange factors regulate the lifetime of the Hsp70-substrate complexes. Furthermore, in vivo, Hsp70 and J-domain cochaperones are modified by posttranslational modifications. The aim of this PhD project will be to analyze the molecular mechanism J-domain proteins in vitro using biochemical and biophysical techniques with purified proteins. Complementary in-vivo-experiments will be carried out in E. coli and mammalian cell culture.

References:
Mayer, M.P. The Hsp70-chaperone machines in bacteria, Front Mol Biosci. (2021) Jun 7;8:694012. doi: 10.3389/fmolb.2021.694012
Mayer, M. P. & Gierasch, L. M. Recent advances in the structural and mechanistic aspects of Hsp70 molecular chaperones. Journal of Biological Chemistry jbc.REV118.002810 (2018). doi:10.1074/jbc.REV118.002810
Kityk, R., Kopp, J. & Mayer, M. P. Molecular Mechanism of J-Domain-Triggered ATP Hydrolysis by Hsp70 Chaperones. Molecular Cell 69, 227 237.e4 (2018).
Kityk, R., Vogel, M., Schlecht, R., Bukau, B. & Mayer, M. P. Pathways of allosteric regulation in Hsp70 chaperones. Nat Commun 6, 8308 (2015).
Mayer, M. P. Hsp70 chaperone dynamics and molecular mechanism. Trends in Biochemical Sciences 38, 507 514 (2013).

Methods that will be used:
Molecular biology methods, Protein purification methods, biochemical assays, fluorescence spectroscopy and mass spectrometry; E. coli and mammalian cell culture.

Profile of candidate s qualification:
The candidate should have a strong background in biochemistry/biophysics and should be highly motivated to succeed in science. Experience in mammalian cell culture would be an advantage.

Please send this form to the HBIGS office by email to: r.lutz@hbigs.uni-heidelberg.de HBIGS Universität Heidelberg PAGE


HBIGS

Universität Heidelberg

PAGE: http://www.hbigs.uni-heidelberg.de/


Project Title: Interaction of human heat shock transcription factor Hsf1 with molecular

Project leader: Matthias P. Mayer
Application Deadline: until position is filled
Start of PhD project: as soon as possible
Source of Funding: DFG

Project Description: Cells are frequently exposed to stressful conditions due to physical or chemical changes in the environment, like changing temperatures, pH, heavy metals, reactive oxygen species (ROS), or toxic compounds, or due to physiological changes intrinsic to differentiation and development, or due to pathophysiological changes during an assault of pathogens. To cope with such conditions a transcriptional program developed early in evolution, called the heat shock response (HSR). Central to the HSR in all eukaryotic cells is the heat shock transcription factor (Hsf1) that up-regulates transcription of a specific set of genes encoding components of the cellular quality control system like molecular chaperones and proteases. Hsf1 also plays a pivotal role in many human diseases like cancer and neurodegenerative pathologies including Parkinson s disease and Ataxias. The central theme of the here advertised two positions is to further our understanding of the molecular mechanism of the regulation of Hsf1, to lay the ground work for future developments of drugs that might activate or inhibit Hsf1 to ameliorate the treatment of the above-mentioned diseases. In previous studies in our lab we could show that Hsf1 is a thermosensor that reacts to the amount of heat absorbed from the environment by transiting from the monomeric to the trimeric state that is capable of binding to DNA and driving transcription. We could further show that Hsp70 chaperones regulate Hsf1 in a negative feedback loop by actively monomerizing the Hsf1 trimers and thereby dissociating them from DNA. However, there are still many questions open.

The successful candidates will analyze the interaction of HSF1 with molecular chaperones and cochaperones in vivo using cell culture model systems and in vitro using purified proteins and biochemical and biophysical methods.

References:
Hentze, N., Le Breton, L., Wiesner, J., Kempf, G. & Mayer, M.P. Molecular mechanism of thermosensory function of human heat shock transcription factor Hsf1. eLife 5:e11576 (2016); doi: 10.7554/eLife.11576
Kmiecik, S.W., Le Breton, L. & Mayer, M.P. Feedback regulation of heat shock factor 1 (Hsf1) activity by Hsp70-mediated trimer unzipping and dissociation from DNA. The EMBO Journal 39:e104096 (2020); doi: 10.15252/embj.2019104096
Kmiecik, S.W., Drzewicka, K., Melchior, F. & Mayer, M.P. Hsf1 is SUMOylated in the activated trimeric state. Journal of Biological Chemistry 296, 100324 (2021); doi: 10.1016/j.jbc.2021.100324

Methods that will be used:
Fluorescence microscopy, life cell imaging, immunoprecipitation, protein purification, in vivo and in vitro protein-protein-interaction assays, fluorescence spectroscopy, hydrogen exchange mass spectrometry, protein-DNA interaction assays (EMSA, fluorescence polarization)

Collaboration partners::


HBIGS

Universität Heidelberg

PAGE: http://www.hbigs.uni-heidelberg.de/