Fachgebiet Zellbiologie

Prof. Dr. Johannes Herrmann

building 13/room 449
Tel.: +49 (0)631-205-2406
Fax: +49 (0)631-205-2492
Email: hannes.herrmann[at]biologie.uni-kl.de

Consulting hours: Wednesday 11:00 - 12:00
more information

Simone Adkins, secretary's office

Tel.: +49 (0)631-205-2490
Fax: +49 (0)631-205-2492
Email: adkins[at]biologie.uni-kl.de
Room: 13-447

Office hours: Monday - Friday from 08.00 - 11.30 am


Steffen Hess - PhD Student

Tel.: +49 (0)631-205-2880
Fax: +49 (0)631-205-2492
Email: hesss(at)rhrk.uni-kl.de
Room: 13-455

 

Project description:

Most of the mitochondrial proteins are synthesized in the cytosol and get imported into the mitochondria. Only a few very hydrophobic membrane proteins are encoded by the mitochondrial genome and get synthesized by the mitochondrial translation machinery, the mitoribosomes. Recently, the structure of yeast and human mitoribosomes has been resolved but the process of mitoribosome assembly is largely unknown. The focus of my work is to better understand how mitoribosomes are assembled in the mitochondrial matrix and how the cell manages to simultaneously provide all the components needed for this process.

Janina Laborenz - PhD Student

Tel.: +49 (0)631-205-2880
Fax: +49 (0)631-205-2492
Email: laborenz(at)rhrk.uni-kl.de
Room: 13-455

 

Project description:

Most mitochondrial proteins are initially synthesized in the cytosol as precursor proteins and imported into mitochondria. While the import of soluble mitochondrial proteins was well studied in the past, only little is known how cells manage to translocate the many hydrophobic membrane proteins of the inner membrane. We found that a large fraction of the newly synthesized inner membrane protein Oxa1 precursor associates with the ER surface from where it is recognized by Djp1 to be directed to the mitochondrial outer membrane translocase. We propose that the ER surface can serve as a collection system that facilities intracellular protein transport to mitochondria. We called this import route the ER-SURF pathway. I am further characterizing this novel import route for mitochondrial precursor proteins, identify additional components involved in this pathway and elucidate the mechanism by which proteins are handed over from the ER to mitochondria.


Anna Schlagowski - PhD Student

Tel.: +49 (0)631-205-2409
Fax: +49 (0)631-205-2492
Email: schlagow[at]rhrk.uni-kl.de
Room: 13-451

 

Project description:

Neurodegenerative diseases such as Parkinson’s disease, Huntington’s disease or Amyotrophic lateral sclerosis are associated with the accumulation of misfolded, aggregating proteins in the cytosol of the patients‘ cells. In these cells, mitochondrial activities are strongly affected. The molecular connection between the formation of aggregates and mitochondrial biogenesis is largely unknown.

The focus of my study is to understand the molecular mechanisms by which aggregates of misfolded proteins affect mitochondrial biogenesis and, vice versa, how changes in mitochondrial biogenesis can affect the toxicity of cytosolic aggregates in yeast cells.

Sreedivya Saladi - PhD Student

Tel. +49 (0)631-205-2111
Fax: +49 (0)631-205-2492
Email: saladi[at]rhrk.uni-kl.de
Room: 24-432

 

Project description:

Mitochondria, apart from their essential role in energy production, are also important players in cell death execution in yeast as they are in higher eukaryotes. Along with their part in ROS generation, mitochondria harbor several factors like AIF, AMID, Nuc1 that up on cellular stress turn into pro-apoptotic agents. The closest homologs of yeast AMID are Nde1 and Nde2 (oxidoreductase in the intermembrane space of mitochondria). In a proteomic screen in our lab, we found that Nde1 is the most unstable protein in mitochondria.  I am studying the proteolytic regulation of Nde1, which apparently is tightly controlled by proteasome/ubiquitin systems of the cytosol and proteases of mitochondria. Further, I am investigating the role of Nde1, as a key regulator of apoptosis and the physiological significance of pro-apoptotic function of Nde1.
 


Eva Zöller- PhD Student

Tel.: +49 (0)631-205-2409
Fax: +49 (0)631-205-2492
Email: zoeller[at]rhrk.uni-kl.de
Room: 13-451

 

Project description:

The intermembrane space of mitochondria contains about 100 different proteins, all of which are synthesized in the cytosol. The translocation of many of these proteins across the TOM complex in the outer membrane is facilitated by the mitochondrial disulfide relay. My research project addresses the question of how this oxidation-dependent import system counteracts cellular stress situations in order to ensure mitochondrial biogenesis under variable physiological conditions.

Sandra Backes - PhD Student

Tel.: +49 (0)631-205-2409
Fax: +49 (0)631-205-2492
Email: s_backes[at]rhrk.uni-kl.de
Room: 13-451

 

Project description:

The majority of mitochondrial proteins are synthesized in the cytosol and need to be imported into mitochondria via different pathways. A variety of targeting signals determine the exact import route for each protein. N-terminal matrix targeting signals (MTSs) direct preproteins to the surface receptors Tom20, Tom22 and Tom70.
The aim of my work is to better understand the role of Tom70 in the import process and to investigate a potential chaperone-like function of the outer membrane receptor.



Systems Biology Team

Mitochondria are separated from the rest of the cell by two membranes and, on the first glance, carry out many of their tasks autonomously on their own. However, both their function and their biogenesis are strongly interconnected with other cellular compartments. Most prominently, mitochondria strictly depend on the supply with proteins from the cytosol. Vice versa, mitochondrial defects have profound impact on the cellular proteostasis network.

Our research focuses on the complex mechanisms that control synthesis, targeting, folding and degradation of mitochondrial proteins in the cytosol. We employ cutting-edge high-throughput technologies (RNAseq, Ribosome Profiling, Mass Spectrometry-based Proteomics, …) to follow the path of proteins on their way from cytosolic ribosomes to the mitochondrial import machinery. The interplay of protein quality control pathways of different cellular compartments is a common theme in our projects.

Felix Boos - PhD Student

Tel.: +49 (0)631-205-2409
Fax: +49 (0)631-205-2492
Email: fboos[at]rhrk.uni-kl.de
Room: 13-451

 

Project description:

Nearly all mitochondrial proteins need to pass the outer mitochondrial membrane through a narrow translocation pore. Stalling of proteins inside the import channel not only cuts off the supply of mitochondria with newly synthesized proteins. It also leads to accumulation of non-imported precursor proteins in the cytosol, which imposes serious proteotoxic stress on the cell. Mitochondrial import problems have been reported in a number of neurodegenerative diseases as well as during the process of aging.

I am studying how cells avoid an overloading of the mitochondrial import machinery and react to mistargeting of precursor proteins. A special interest in my research is the regulation of adaptive cellular programs that balance the synthesis and degradation of mitochondrial proteins with the capacity of the translocation system.

Carina Groh- PhD Student

Tel. +49 (0)631-205-2797
Fax: +49 (0)631-205-2492
Email: cgroh[at]rhrk.uni-kl.de
Room: 13-430

 

Project description:

The function of the cell depends on properly folded proteins. To maintain the functional activity of the proteins, a complex network of molecular chaperones, the ubiquitin-proteasome system and many cofactors are required. If this orchestra fails and protein folding is impaired, the cell has to deal with many issues. Neurodegenerative diseases or aging are extreme examples of what might happen when protein folding becomes problematic. Recent studies revealed that also mitochondrial problems lead to cytosolic proteotoxic stress.

Until today it remains unclear what the precise effect of different proteotoxic stresses on cellular functionality is. In this context I will study the impact of mitochondrial stress on the cytosolic proteostasis.

Lena Krämer - PhD Student

Tel. +49 (0)631-205-2797
Fax: +49 (0)631-205-2492
Email: l_kraeme[at]rhrk.uni-kl.de
Room: 13-430

 

Project description:

A functional mitochondrial protein import is essential for cellular fitness and survival. A loss of protein translocation is associated with oxidative stress, neurodegenerative diseases as well as metabolic disorders. As in other stress situations, the cell performs a strongly regulated stress reaction after mitochondrial import block. In this mitoprotein-induced stress response, the proteasome plays a crucial role, as it degrades mitochondrial precursor proteins which accumulate in the cytosol.

In my studies I concentrate on the molecular mechanisms by which the proteasome plays a role during mitochondrial biogenesis.

Katharina Knöringer - PhD Student

Tel.: +49 (0)631-205-2409
Fax: +49 (0)631-205-2492
Email: knoering[at]rhrk.uni-kl.de
Room: 13-451

 

Project description:

Mitochondria have an elaborate machinery to import proteins that are synthesized on cytosolic ribosomes. Many different pathways and mechanisms of protein translocation across the mitochondrial membranes are studied in great detail. In contrast, very little is known about how the proteins reach the mitochondrial import channels in the first place.

For a long time, it was believed that all mitochondrial proteins are first completely synthesized in the cytosol and then subsequently targeted to mitochondria in a post-translational manner. In the last years, this dogma has been challenged by compelling evidence for the existence of co-translational import. At least some proteins appear to be translated in direct vicinity to the translocation channel and their import likely starts before translation is completed. However, the extent and physiological relevance of co-translational import remain elusive.

I am interested in how the cell decides between co- and posttranslational import. Another focus of my studies will be environmental conditions which have an impact on the balance between the two import modes.


Bachelor/Master Students

Joshua Baal - Master Student

Tel.: +49 (0)631-205-2409
Fax: +49 (0)631-205-2492
Email: jbaal[at]rhrk.uni-kl.de
Room: 13-451


Jana Friedl - Master Student

Tel.: +49 (0)631-205-2797
Fax: +49 (0)631-205-2492
Email: friedl[at]rhrk.uni-kl.de
Room: 13-430


 

 

Kimberly Katt- Master Student

Tel.: +49 (0)631-205-2111
Fax: +49 (0)631-205-2492
Email: katt[at]rhrk.uni-kl.de
Room: 13-432


 

 

Tamara Flohr - Master Student

Tel.: +49 (0)631-205-2880
Fax: +49 (0)631-205-2492
Email: tflohr[at]rhrk.uni-kl.de
Room: 13-455


Caroline Erler- Bachelor Student

Tel.: +49 (0)631-205-2797
Fax: +49 (0)631-205-2492
Email: erler[at]rhrk.uni-kl.de
Room: 13-430

Technische Mitarbeiter

Sabine Knaus

Tel. +49 (0)631-205-2880
Fax +49 (0)631-205-2492
Email: s.knaus[at]biologie.uni-kl.de
Room: 13-455


Vera Nehr

Tel. +49 (0)631-205-2797
Fax +49 (0)631-205-2492
Email: vfritzin[at]rhrk.uni-kl.de
Room: 13-430


Andrea Trinkaus

Tel. +49 (0)631-205-2111
Fax +49 (0)631-205-2492
Email: trinkaus[at]biologie.uni-kl.de
Room: 13-432

Cornelia Parent

Tel. +49 (0)631-205-2490
Fax +49 (0)631-205-2492
Email: parent[at]rhrk.uni-kl.de
Room: 13-423

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