Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Molecular Transport Logistics

25.05.2010
The Handicraft Of Cellular Transport Complexes

A protein complex, which is an important link in a cellular transport chain, also initiates the assembly of the next link in the chain.

This newly-won insight will now allow a better understanding of a transport process that plays a crucial role in numerous cellular processes including virus infections, cell division and signal transmission. The additional function of the ESCRT-II transport complex was discovered during the course of a research project funded by the Austrian Science Fund FWF and recently reported in The EMBO Journal .

Virus infections, cell division and signal transmission have something in common: they make use of a "protein machine" that actually controls a cell disposal process. The assembly of this molecular "machine" is highly controlled and is mainly influenced by five particular protein complexes. The protein complexes in question are referred to as ESCRTs (endosomal-sorting complex required for transport). A team from Innsbruck Medical University and Cornell University in the USA has now discovered a surprising function of one of the ESCRT complexes (No II): ESCRT-II also initiates the assembly of ESCRT-III, the central complex in the transport chain.

MOLECULAR TRAFFIC CONTROL
All ESCRTs share the function of loading the cellular transport vesicles (MVB - multi vesicular bodies) with cell surface components that have become "unwanted". For this purpose, the ESCRTs are generated only temporarily. Dr. David Teis from the Division of Cell Biology at Innsbruck Medical Hospital explains the new function of one of the ESCRTs discovered by his team as follows: "A part of ESCRT-II, known as Vps25, triggers a kind of chain reaction, which initially gives rise to a structural change in another protein called Vps20. Vps20 is more or less activated by the structural change and other proteins - SnF7s - can then group around Vps20. Subsequently, the rest of the ESCRT-III forms around this starting point. In this way, ESCRT-II initiates the assembly of ESCRT-III."

To be more precise, approximately 10 - 20 Snf7 proteins must assemble in a defined ring-like form so that the other ESCRT-III components can be added as required. It is precisely this ring-like grouping of the Snf7 proteins that is influenced by the Vps25. The team working with Dr. Teis was able to discover this through experiments involving the clever modification of ESCRT-IIs: instead of the usual two Vps25s, only one was used for ESCRT-II. Dr. Teis explains: "This enabled us to show that, despite the reduced number of Vps25s in the ESCRT-II, the Snf7s still grouped together. However, the molecules that assembled in this way were not able to fulfill the biological function of ESCRT-III."

NO "O" WITHOUT "Y"
Based on the known fact that the two Vps25 proteins of the ESCRT-II form a Y-shaped structure, Dr. Teis made the following deduction from this finding: the two arms of the Y formed by the Vps25 together enable the suitable ring-shaped arrangement of the Snf7 molecules. While one "arm" is sufficient to group the Snf7s, two Snf7s must be deposited - one on each arm - for the spatial structure to accommodate the further assembly of the ESCRT-III.

This ring structure then acts as a kind of master copy for the MBV transport vesicles. This assumption was confirmed in a further experiment which Dr. Teis carried out with his co-operation partner Professor Scott Emr from Cornell University in the USA. For this experiment, more Snf7 molecules than usual were formed in cells with an altered molecular composition. The result? The vesicles that formed in these cells were significantly larger - providing a clear indication of the role of the Snf7 protein as a master copy.

In summary, these results, stemming from an FWF project, not only reveal the extent to which this cellular disposal mechanism is finely tuned, but also demonstrate its hitherto unknown capacity for molecular self-assembly.

Image and text will be available from Tuesday, 25th May 2010, 9.00 a.m. CET onwards:

http://www.fwf.ac.at/en/public_relations/press/pv201005-en.html

Original publication: ESCRT-II coordinates the assembly of ESCRT-III filaments for cargo sorting and multivesicular body vesicle formation, D. Teis, S. Saksena, B. Judson and S. D. Emr, The EMBO Journal (2010) 29, 871 - 883 doi:10.1038/emboj.2009.408

Scientific contact:
Dr. David Teis
Innsbruck Medical University
Division of Cell Biology
Fritz-Pregl Str. 3
6020 Innsbruck
T +43 / 512 / 9003 - 70175
E david.teis@i-med.ac.at
The Austrian Research Foundation FWF:
Mag. Stefan Bernhardt
Haus der Forschung
Sensengasse 1
1090 Vienna
T +43 / 1 / 505 67 40 - 8111
E stefan.bernhardt@fwf.ac.at
Publication and distribution:
PR&D - Public Relations für Forschung & Bildung Campus Vienna Biocenter 2 1030 Vienna T +43 / 1 / 505 70 44 E contact@prd.at W http://www.prd.at

| PR&D
Further information:
http://www.fwf.ac.at

More articles from Life Sciences:

nachricht Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute

nachricht Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>