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Current Research


[Role of protein phosphorylation in yeast mitochondria]

[Essential role of mitochondria in stem cell development]

[Mitochondrial copper homeostasis in mammalian cells]

[Nanoparticles in biological systems]

[Mitochondrial biogenesis in Schizosaccharomyces pombe]

[Biological components in sensor systems]

[Optimization of heterologous gene expression in S. pombe]

[Expression and modification of self-assembling proteins]




Introduction


Our group is interested in the biogenesis of mitochondria which play a major role in cellular energy metabolism of eukaryotic cells. We are studying the genetical and molecular basis of mitochondrial (mt) biogenesis in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, which are both excellent eukaryotic model organisms. Current interest is focused on the function and topology of nuclearly assembly of respiratory chain complexes. Furthermore we analyze the function of human orthologous.
encoded mitochondrial proteins, which assist the synthesis and In our applied fieldsort research we use bacteria and yeasts as cell factories for genetically modified proteins. The recombinant proteins are genetically engineered for technical application, e.g. in biosensors. Of special interest are proteins with an inherent ability to self assemble under in vitro conditions. In the following, a compilation of actual projects is given.
For further informations contact:

Prof. Dr. Gerhard Rödel


Role of protein phosphorylation in yeast mitochondria

The physiological role of reversible protein phosphorylation in the mt compartment is largely unknown as are the corresponding enzymes. We aim to identify yeast enzymes of the mt reversible phosphorylation and their target proteins in order to elucidate their physiological function. To this end deletion mutants of putative mt protein kinases or - phosphatases are analysed regarding their phenotype (respiratory chain function, mt morphology) and their phosphoproteome by a combination of complementary 2D-electrophoretic and chromatographic techniques. Due to the evolutionary conservation of the yeast and mammalian mt system, many of the results may also be valid for mammals.
For further information contact:

Prof. Dr. Gerhard Rödel
Dr. Udo Krause-Buchholz (link)
Dipl. Biol.Uta Gey
Dipl. Biol. Anja Tauche

     

Essential role of mitochondria in stem cell development

Mitochondria play a pivotal role in eukaryotic cells. Beside their role in energy supply mitochondria are the site of iron-sulfur cluster assembly and a number of other essential metabolic pathways. The role of mitochondria in triggering apoptosis is well-known, but it is becoming evident that they are also important for cell differentiation processes. Due to the very distinct metabolic and energetic demands of different cell types, differentiation processes require appropriate changes in mt function. This includes coordinated assembly of the respiratory chain (RC) complexes to yield a balanced electron influx by complexes I, II and III, and final terminal reduction of oxygen by complex IV (cytochrome c oxidase, COX). Failure of any of the RC complexes results in a decline of membrane potential across the inner mt membrane which is the driving force for ATP production by F1F0 ATPase. The diminished ATP supply affects primarily cells or tissues with a high energy demand, especially neurons and muscle cells, and may result in metabolic disorders which finally lead to serious diseases or to lethality. In this project, we analyse the assembly and activity of the RC complexes and the mt proteome at different stages of cellular development to elucidate its role in stemm cell differentiation.

Prof. Dr. Gerhard Rödel
Dr. Udo Krause-Buchholz
Dipl. Biol. Andreas Hofmann


     

Mitochondrial copper homeostasis in mammalian cells

Cytochrome c oxidase (COX) is an essential, evolutionary highly conserved enzyme of the mt respiratory chain that catalyses the reduction of molecular oxygen by reduced cytochrome c. The three largest subunits, encoded by mtDNA, form the catalytic core of the enzyme. Activity of the enzyme is dependent on a couple of redox active metal centres, among them the two copper binding sites CuA- and CuB. Incorporation of copper is crucial for the assembly and activity of the enzyme.
Eukaryotic cells utilize copper in the cytoplasm (SOD, superoxide dismutase), mitochondria (COX), and the endoplasmatic reticulum. Copper ions are delivered by special copper chaperones in a highly regulated way to the sites of utilization. For delivery to COX, copper ions have to be transported from the cytosol to mitochondria and to be incorporated into the two copper binding sites. Copper ions are present in the mt intermembrane space, and recent data suggest that copper ions may enter the mt matrix to be eventually recruited at a later stage to the intermembrane space. In the yeast Saccharomyces cerevisiae, several mt proteins involved in copper delivery to COX have been identified, among them the soluble proteins Cox17p, Cox19p, Cox23p and the inner membrane proteins Sco1p, Sco2p and Cox11p. These proteins are evolutionary conserved, and recent studies have identified the pivotal role of some of them in human diseases.
This project addresses the role of proteins involved in mammalian mt copper metabolism and COX assembly by gene-specific RNAi-knockdown in cultured human cells.


Prof. Dr. Gerhard Rödel
Dr. Udo Krause-Buchholz
Dipl. Biochem. Corina Oswald


     

Nanoparticles in biological systems

Due to their small size nanoparticles (NP) exhibit a variety of unique physical and chemical properties, including surface characteristics, fluorescence and other optical features. In collaboration with the Institute of Materia Science, we test different NPs, e.g. gold particles, for their application in biological systems as addressable cargos.

Prof. Dr. Gerhard Rödel
Dr. Udo Krause-Buchholz
Dipl. Biol. Msaukiranji Mkandawire


     

Mitochondrial biogenesis in Schizosaccharomyces pombe

The fission yeast S. pombe, which is phylogenetically as far apart from S. cerevisiae as from man, is established as a useful model organism for eukaryotic molecular biology. The genome of S. pombe has revealed many genes with a high degree of homology to genes in S. cerevisiae that are involved in mt biogenesis.
We are studying the functional conservation of the homologous proteins by complementation analysis of S. cerevisiae mutants. The molecular function and topology of the proteins in S. pombe is analyzed by molecular genetical methods such as gene deletions, tetrad analysis, GFP-fusions, mutagenesis etc.

Prof. Dr. Gerhard Rödel
Dr. Kai Ostermann


     

Biological components in sensor systems

Biosensors have a high potential for application in a variety of technical processes, e.g. in biotechnology and in medicine.
We are using yeasts as "whole cell sensors" as well as engineered recombinant proteins of different organisms for the functionalization of sensors.
The projects are in close collaboration with different institutes of the TU Dresden and some industrial partners.

Prof. Dr. Gerhard Rödel
Dr. Kai Ostermann
Dipl. Biol. Annett Groß
Dipl. Biol. Karolina Ihle
Dipl. Biol. Simone Thierfelder
B.Sc. Andre Clemens


     

Optimization of heterologous gene expression in S. pombe

The aim of this project is to express high levels of heterologous proteins in S. pombe. To this end, S. pombe strains are genetically modified in order to increase the biosynthetic capacity. One focus is optimization of secretion, another aspect addresses high-cell density fermentation. The project is in close collaboration with the group of Prof. Bley (Institute of Food Technology and Bioprocess Engineering) at the TU Dresden.
Furthermore yeasts are genetically modified to improve biodegradation processes. This project is in close collaboration with industrial partners.

Prof. Dr. Gerhard Rödel
Dr. Kai Ostermann
Dipl. Biol. Kirsten Kottmeier
Dipl. Biol. Susann Lauffer
Dipl. Biol. Susann Kurtz


     

Expression and modification of self-assembling proteins

In this research area we focus on self-assembling proteins of procaryotes (S-layer proteins) and fungi (hydrophobins).
S-layer proteins cover the surface of some bacteria. Isolated S-layer proteins form highly ordered self assemblages in vitro, what makes them attractive for technical applications, e.g. as scaffolds in the field of nano-biotechnology.
S-layer genes are cloned, highly expressed in appropriate host systems, and subjected to biochemical and/or biophysical analysis. S-layer genes are genetically engineered to modify their properties for technical applications.
Hydrophobins are small proteins of around 100 amino acids, that are produced by fungi at different stages of their life cycle. Hydrophobins self assemble to amphipatic protein films at phase borders.
We are cloning and expressing hydrophobin genes in appropiate host systems (yeasts, E. coli). The proteins are modified for improving their use in technical applications.
The projects are in close collaboration with the Institute of Materia Science, the Institute for Solid-State Electronics, and different companies.

Prof. Dr. Gerhard Rödel
Dr. Kai Ostermann
Dipl. Chem. Katrin Ferse
Dipl. Chem. Denise Knobloch
Nuriye Korkmaz MSc. Mol. Bioeng. Melinda Varga
Last modified: 06.05.2013 14:14
Author: Lucas Schirmer

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