Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Structure of the Cellular Recycling Bin

31.01.2014
When the refuse disposal service goes on strike, heaps of trash will pile up on streets and attract vermin like mice and rats.

In a similar way, a cellular waste management system constantly picks up superfluous proteins and damaged organelles in human cells and delivers them to recycling facilities. However, if the cellular waste management system stops working, severe illnesses like Alzheimer´s disease or cancer may develop.


Capture:
The picture shows the structure of the autophagic scaffold. The scientists used atomic force microscopy to visualize the hight profile of the scaffold on artificial membranes. The protein meshwork rises gradually (yellow-red) from the ground level of the membrane (black) to the crest of the scaffold (white) where it reaches its maximum hight. The resulting two-dimensional map was then projected onto a sphere which represents the autophagosome.
Picture: Thomas Wollert
Copyright: MPI of Biochemistry

Scientists at the Max Planck Institute of Biochemistry in Martinsried near Munich, Germany, recently revealed how a major cellular recycling system – autophagy – works. The results of the study have now been published in the research journal Cell.

The autophagic system in cells captures cellular waste and delivers it to specialized recycling facilities, called lysosomes. Thus autophagy protects the cell from accumulating cell debris. If autophagy slows down or stops working, severe diseases like cancer, Parkinson´s or Alzheimer´s disease may occur.

Much in the same way as trash bags envelop waste, a membrane engulfs cellular debris during autophagy. This molecular “recycling bag” is called autophagosome. After the membrane has been wrapped around the waste, it is transported to lysosomes for degradation. Because lysosomes are also surrounded by membranes, autophagosomes are able to fuse with them to deliver their content without leakage. Finally, an armada of different enzymes degrades the lysosomal content into its basic molecular building blocks.

Cellular waste differs enormously in size and shape, imposing a major challenge for the autophagic system. On the one hand the membrane of autophagosomes needs to be flexible enough to engulf the waste. On the other hand, mechanical stability is needed to guide the membrane around the waste in a zipper-like fashion. Thomas Wollert and his Research Group “Molecular Membrane and Organelle Biology” now revealed the molecular architecture of an autophagic membrane scaffold, which mechanically supports autophagosomes.

Small meshes – large effects
The scaffold is a flat meshwork made of proteins that cover the membrane of the autophagosome entirely. The vertices of the mesh consist of the small protein Atg8 which is attached to the autophagic membrane and serves as a molecular anchor. A second protein complex cross-links Atg8 to build up the scaffold. One mesh is only 16 nm long, i.e. 10.000-fold shorter than a human hair is thick, and the scaffold is only 8 nm thick. When the membrane has entirely enveloped the molecular waste, the scaffold is no longer needed and removed by an enzyme which cuts Atg8 from the membrane.

Furthermore, the researchers were able to recreate the scaffold on artificial membranes in the test tube and to follow its assembly and disassembly in real time. “It is important that we understand the molecular mechanisms that drive autophagy to be able to modulate its speed”, said Thomas Wollert, MPIB group leader who supervised the study. “If we were able to accelerate autophagy, Alzheimer´s disease and other neurological disorders could perhaps be cured in the future.” [VS]

Original Publication:
Kaufmann A., V. Beier, H. G. Franquelim and Wollert T., Molecular Mechanism of Autophagic Membrane-Scaffold Assembly and Disassembly, Cell, January 30, 2014.

DOI: 10.1016/j.cell.2013.12.022

Contact
Dr. Thomas Wollert
Molecular Membrane and Organelle Biology
Max Planck Institute of Biochemistry
Am Klopferspitz 18
82152 Martinsried
Germany
Email: wollert@biochem.mpg.de
www.biochem.mpg.de/wollert
Anja Konschak
Public Relations
Max Planck Institute of Biochemistry
Am Klopferspitz 18
82152 Martinsried
Germany
Tel. +49 89 8578-2824
E-Mail: konschak@biochem.mpg.de
www.biochem.mpg.de
Weitere Informationen:
http://www.biochem.mpg.de/en/news/pressroom
- Press Releases of Max Planck Institute of Biochemistry
http://www.biochem.mpg.de/en/rg/wollert
- Website of the Research Group "Molecular Membrane and Organell Biology"

Anja Konschak | Max-Planck-Institut
Further information:
http://www.biochem.mpg.de

More articles from Life Sciences:

nachricht Not of Divided Mind
19.01.2017 | Hertie-Institut für klinische Hirnforschung (HIH)

nachricht CRISPR meets single-cell sequencing in new screening method
19.01.2017 | CeMM Forschungszentrum für Molekulare Medizin der Österreichischen Akademie der Wissenschaften

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

New Study Will Help Find the Best Locations for Thermal Power Stations in Iceland

19.01.2017 | Earth Sciences

Not of Divided Mind

19.01.2017 | Life Sciences

Molecule flash mob

19.01.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>