Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Speedy couriers in the cell

"Optical tweezers"
"Optical tweezers"

Abstract:
Why motor proteins have brakes

Speedy couriers in the cell

Germany | Posted on May 24th, 2010

Every single one of our cells contains so-called motor proteins that transport important substances from one location to another. However, very little is known about how exactly these transport processes occur. Biophysicists at the Technische Universitaet Muenchen (TUM) and Ludwig Maximilians Universitaet Muenchen (LMU) have now succeeded in explaining fundamental functions of a particularly interesting motor protein. They report their findings in the current issue of the Proceedings of the National Academy of Sciences (USA).

Motorized transport proteins are one of the keys to the development of higher organisms. It is they that enable the cell to transport important substances directly and quickly to a specific location in the cell. As bacteria cannot do this, they are not able to form larger cells or even large organisms with many cells. Particularly important are fast transport proteins in the primary cilia, the cell's antennas, with which they channel information from the surroundings into the cell.

Like trucks on a highway, kinesins transport cellular loads to their destinations. They do this by crawling along protein fibers, so-called microtubules, which extend through the entire cell. Kinesins consist of two long intertwined protein chains. At one end of every protein there is a head that can attach itself to certain structures on the surface of the microtubules; the freight is attached to the other end.

Very special kinesins are at work in the cilia of the Caenorhabditis elegans nematode: they consist of two different protein chains and are therefore especially suitable for investigating the transport mechanisms. As freight, the researchers attached small plastic beads to the ends of these motor proteins. They can manipulate these beads with "optical tweezers," a specially formed laser beam.

One end of the protein molecule was held with the optical tweezers; the other was able to walk on microtubules. This enabled the scientists to measure the force with which the motor protein can pull. In this experimental setup, the kinesin-2 with its freight walks as far as 1,500 nanometers in tiny steps measuring a mere eight nanometers. "If we didn't hold it back, it might still go a lot further," says Zeynep Ökten from the Institute for Cell Biology at LMU.

The kinesin-2 investigated consists of one KLP11 and one KLP20 protein. By exchanging the heads of the chains, the researchers were able to show that KLP11 is a non-processive motor protein. It only becomes a transport protein in combination with KLP20. In further experiments they were able to explain why nature chooses this unusual combination: KLP20 proteins have no "brakes." A transport protein made of two KLP20 units would be permanently on the go and would waste energy. The KLP11, in contrast, has a mechanism called autoinhibition, which makes sure that the transport protein is at a standstill if no freight is attached.

"Our results show that a molecular motor must take on a large number of functions over and above simple transport, if it wants to operate successfully in a cell," says Professor Matthias Rief from the Physics Department of the TU Muenchen. It must be possible to switch the motor on and off, and it must be able to accept a load needed at a specific location and hand it over at the destination. "It is impressive how nature manages to combine all of these functions in one molecule," Rief says. "In this respect it is still far superior to all the efforts of modern nanotechnology and serves as a great example to us all."

This work was supported by funds from the Cluster of Excellence Center for Integrated Protein Science Munich (CIPSM), a Long Term European Molecular Biology Organization fellowship and grants from the Deutsche Forschungsgemeinschaft (DFG) and the Friedrich-Baur-Stiftung.

Original Publication:

Regulation of a heterodimeric kinesin-2 through an unprocessive motor domain that is turned processive by its partner,
Melanie Brunnbauer, Felix Mueller-Planitz, Süleyman Kösem, Thi-Hieu Hoa, Renate Dombi, J. Christof M. Gebhardt, Matthias Rief, and Zeynep Ökten
PNAS Early Edition, May 17, 2010 - www.pnas.org/cgi/doi/10.1073/pnas.1005177107

####

For more information, please click here

Contacts:
Prof. Matthias Rief
Chair for Experimental Physics (E 22)
Technische Universitaet Muenchen
James-Franck-Str. 1, 85748
Garching, Germany
Tel: +49 89 289 12471
Fax: +49 89 289 12523

Copyright © Technische Universitaet Muenchen

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Automating DNA origami opens door to many new uses: Like 3-D printing did for larger objects, method makes it easy to build nanoparticles out of DNA May 30th, 2016

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Govt.-Legislation/Regulation/Funding/Policy

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Harnessing solar and wind energy in one device could power the 'Internet of Things' May 26th, 2016

Thermal modification of wood and a complex study of its properties by magnetic resonance May 26th, 2016

Academic/Education

Graphene: Progress, not quantum leaps May 23rd, 2016

Smithsonian Science Education Center and National Space Society Team Up for Next-Generation Space Education Program "Enterprise In Space" May 11th, 2016

The University of Colorado Boulder, USA, combines Raman spectroscopy and nanoindentation for improved materials characterisation May 9th, 2016

Albertan Science Lab Opens in India May 7th, 2016

Molecular Machines

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

Researchers create artificial protein to control assembly of buckyballs April 27th, 2016

Physicists build engine consisting of one atom: World's smallest heat engine uses just a single particle April 17th, 2016

Revealing the fluctuations of flexible DNA in 3-D: First-of-their-kind images by Berkeley Lab-led research team could aid in use of DNA to build nanoscale devices March 31st, 2016

Announcements

Automating DNA origami opens door to many new uses: Like 3-D printing did for larger objects, method makes it easy to build nanoparticles out of DNA May 30th, 2016

Simple attraction: Researchers control protein release from nanoparticles without encapsulation: U of T Engineering discovery stands to improve reliability and fabrication process for treatments to conditions such as spinal cord damage and stroke May 28th, 2016

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Doubling down on Schrödinger's cat May 27th, 2016

Tools

Scientists illuminate a hidden regulator in gene transcription: New super-resolution technique visualizes important role of short-lived enzyme clusters May 27th, 2016

Light can 'heal' defects in new solar cell materials: Defects in some new electronic materials can be removed by making ions move under illumination May 24th, 2016

More light on cancer: Scientists created nanoparticles to highlight cancer cells May 21st, 2016

Nanotubes are beacons in cancer-imaging technique: Rice University researchers use spectral triangulation to pinpoint location of tumors May 21st, 2016

Photonics/Optics/Lasers

Attosecond physics: A switch for light-wave electronics May 24th, 2016

Photon collisions: Photonic billiards might be the newest game! May 20th, 2016

We’ll Leave the Lights On For You: Photonics advances allow us to be seen across the universe, with major implications for the search for extraterrestrial intelligence, says UC Santa Barbara physicist Philip Lubin - See more at: http://www.news.ucsb.edu/2016/016805/we-ll-leave-li May 17th, 2016

UW researchers unleash graphene 'tiger' for more efficient optoelectronics May 16th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic