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 'Y' a protein unicorn might matter in glaucoma
23.10.2017 | Georgia Institute of Technology

nachricht Microfluidics probe 'cholesterol' of the oil industry
23.10.2017 | Rice University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>