Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

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

Haydale and Goodfellow Announce Major Distribution Agreement for Functionalised Graphene Materials July 21st, 2014

Relaunch of the Nanoscribe Website New design, optimized research, and impressive gallery of applications July 21st, 2014

Dongbu HiTek Unveils Low-Voltage BCDMOS Process for Efficient Power Management in Smart Phones and Tablet Computers July 21st, 2014

Iran to Host 1st Asian Congress on Nanostructures on Kish Island July 21st, 2014

Govt.-Legislation/Regulation/Funding/Policy

Oregon chemists eye improved thin films with metal substitution: Solution-based inorganic process could drive more efficient electronics and solar devices July 21st, 2014

More than glitter: Scientists explain how gold nanoparticles easily penetrate cells, making them useful for delivering drugs July 21st, 2014

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

Tiny laser sensor heightens bomb detection sensitivity July 19th, 2014

Academic/Education

Haydale Announces Collaboration Agreement with Swansea University’s Welsh Centre for Printing and Coatings (WCPC) July 12th, 2014

STFC takes delivery of the 100th Hitachi Tabletop SEM in the UK July 3rd, 2014

Innovation Management and the Emergence of the Nanobiotechnology Industry July 1st, 2014

Albany NanoCollege Faculty Member Selected as Editor-in-Chief of the Prestigious Journal of Electronic Materials July 1st, 2014

Molecular Machines

University of Illinois researchers demonstrate novel, tunable nanoantennas July 14th, 2014

Ribosome Research in Atomic Detail Offers Potential Insights into Cancer, Anemia, Alzheimer’s: New movement during decoding occurs in humans, not in bacteria July 3rd, 2014

Nanoscale velcro used for molecule transport June 25th, 2014

Design of self-assembling protein nanomachines starts to click: A nanocage builds itself from engineered components June 5th, 2014

Announcements

Oxford Instruments Asylum Research Opens an Atomic Force Microscopy Demonstration Lab in Mumbai, India July 21st, 2014

Steam from the sun: New spongelike structure converts solar energy into steam July 21st, 2014

More than glitter: Scientists explain how gold nanoparticles easily penetrate cells, making them useful for delivering drugs July 21st, 2014

Iran to Host 1st Asian Congress on Nanostructures on Kish Island July 21st, 2014

Tools

Dongbu HiTek Unveils Low-Voltage BCDMOS Process for Efficient Power Management in Smart Phones and Tablet Computers July 21st, 2014

Oxford Instruments Asylum Research Opens an Atomic Force Microscopy Demonstration Lab in Mumbai, India July 21st, 2014

Martini Tech Inc. becomes the exclusive distributor for Yoshioka Seiko Co. porous chucks for Europe and North America July 20th, 2014

Sono-Tek Corporation Announces New Clean Room Rated Laboratory Facility in China July 18th, 2014

Photonics/Optics/Lasers

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

Tiny laser sensor heightens bomb detection sensitivity July 19th, 2014

Future Electronics May Depend on Lasers, Not Quartz July 17th, 2014

"Nanocamera" takes pictures at distances smaller than light's own wavelength: How is it possible to record optically encoded information for distances smaller than the wavelength of light? July 17th, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE