Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Protein Team Produces Molecular Barrels

05.08.2013
Researchers show that two protein machineries collaborate on the development of barrel structures in the mitochondria

Research groups headed by Prof. Dr. Nikolaus Pfanner, Dr. Nils Wiedemann, and Dr. Thomas Becker from the University of Freiburg and their colleagues have demonstrated how molecular protein barrels form in the outer membrane of the mitochondria, the powerhouses of the cell. Their studies revealed that two protein machineries cooperate in an unexpected way. The researchers published their findings in the scientific journal “Cell”.


The protein machineries TOM und SAM are linked via Tom22 and work together in the maturation process of beta-barrel structures of proteins. Modified from Becker et al., 2008; Biochim. Biophys. Acta 1777, 447-563 © Thomas Becker (BBA-2008)

Mitochondria are essential for the survival of the cell, rendering such vital services as providing the energy for cell metabolism. Mitochondria are surrounded by two membranes. The outer membrane contains characteristic proteins with a barrel-like structure, the beta-barrel structure. These proteins extend across the membrane and are crucial for the transport of proteins and metabolic products into the mitochondria. The proteins are produced as precursors in the cytosol, only forming their mature barrel structure upon entering the mitochondrion.

They are imported through the pores of the protein complex TOM, the translocase of the outer mitochondrial membrane, and then transported to a second protein machinery in the outer membrane, the sorting and assembly machinery SAM. Finally, the SAM complex integrates the proteins into the membrane. The individual steps leading to the formation of the beta-barrel structure and the transfer of the precursor protein from TOM to SAM were not previously understood.

The researchers studied the formation of the beta-barrel structure within the context of a partnership between the Collaborative Research Center 746 “Functional Specificity by Coupling and Modification of Proteins,” the Cluster of Excellence BIOSS Centre for Biological Signalling Studies, and the Spemann Graduate School of Biology and Medicine.

The team headed by Nils Wiedemann demonstrated that the beta-barrel structure forms at the SAM complex. The PhD student Jian Qiu discovered that the receptor protein Tom22 plays a key role in this process. This comes as a surprise, because it was previously thought that TOM and SAM were independent protein machineries. However, findings from Thomas Becker’s research group showed that the two complexes directly interact with each other. They are linked by Tom22, as the PhD student Lena-Sophie Wenz discovered. If Tom22 is not present, the molecular bridge between TOM and SAM is lost – severely hampering the formation of beta-barrel structures. The findings of this study demonstrate that the direct transfer of the imported protein from the TOM complex to the SAM complex enables an efficient formation of mitochondrial beta-barrel structures.

Original publication:
Jian Qiu, Lena-Sophie Wenz, Ralf M. Zerbes, Silke Oeljeklaus, Maria Bohnert, David A. Stroud, Christophe Wirth, Lars Ellenrieder, Nicolas Thornton, Stephan Kutik, Sebastian Wiese, Agnes Schulze-Specking, Nicole Zufall, Agnieszka Chacinska, Bernard Guiard, Carola Hunte, Bettina Warscheid, Martin van der Laan, Nikolaus Pfanner, Nils Wiedemann, and Thomas Becker (2013) Coupling of Mitochondrial Import and Export Translocases by Receptor-Mediated Supercomplex Formation. Cell, Volume 154, Issue 3, 596-608, doi: 10.1016/j.cell.2013.06.033
Contact:
PD Dr. Thomas Becker
Institute of Biochemistry and Molecular Biology
University of Freiburg
Phone: +49 (0)761/203-5243
E-Mail: thomas.becker@biochemie.uni-freiburg.de

Rudolf-Werner Dreier | University of Freiburg
Further information:
http://www.uni-freiburg.de

More articles from Life Sciences:

nachricht Topologische Quantenchemie
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

nachricht Topological Quantum Chemistry
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>