Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Revealing the inner workings of a molecular motor

12.01.2015

In research published in the Journal of Cell Biology, scientists from the RIKEN Brain Science Institute in Japan have made important steps toward understanding how dynein--a "molecular motor"--walks along tube-like structures in the cell to move cellular cargo from the outer structures toward the cell body of neurons. The action of this molecule is important for a number of cell functions including axonal transport and chromosome segregation, and its dysfunction is known to lead to a congenital developmental brain disorder known as lissencephaly.

Though cells may look like shapeless blobs of liquid encased in a membrane, in fact they have a complex skeleton-like structure, known as the cytoskeleton, made up of filaments called microtubules. Motor proteins, which include dynein and kinesin, can move along these tubules to transport cargo into and out of the center of the cell.


Schematic representation of the dynein-microtubule complex showing the structural elements likely to be involved in allosteric communication between the microtubule and the ATPase site in dynein

The motor proteins use an energy-currency molecule, ATP, to power their movements along the microtubules. The motor proteins hydrolyze ATP to ADP, and convert the released chemical energy to mechanical energy which is used for movement. The mechanism is quite well understood for kinesin, but in the case of dynein, it has been difficult to explain how communication takes place between the site of microtubule binding and the site of ATP hydrolysis, which are relatively far from each other, separated by a stalk.

In the new research, performed in collaboration with several other institutes including the University of Osaka, Waseda, and Hosei University, the RIKEN scientists used cryo electron microscopy--where molecules are cooled to very low temperatures in the microscope--and examined the structure of dynein on the microtubule.

They showed that two specific amino acid residues on the microtubule structure, R403 and E416, are key to turning on the switch that is critical for the activation of the dynein motor--demonstrating that when mutations in these sequences are present, the dynein fails to achieve directional movement on the microtubule, ending up simply moving back and forth in a random fashion.

This lends weight to the idea, that has been generally accepted, that the motion of molecular motors is basically driven by random, Brownian motion, and that motors are able to move in one direction thanks to subtle changes in the strength of bonds at the motor-microtubule interface.

Additionally, the group discovered that turning on the mechanical switch at the motor-microtubule interface leads to ATP hydrolysis. Their results altogether indicate that the subtle structural changes in the bonds at the interface are transmitted through a small change in the structure of the stalk--there are two coils that link the two binding regions, and a small shift in the configuration of the coils gives the cue for ATP hydrolysis at the ATP binding site.

Seiichi Uchimura, the first author of the paper, said, "We were able to clearly demonstrate that the dynein molecular motor is activated by a 'switch' that controls mutual interactions between dynein and the microtubule. This is important, as a mutation in the structure of the switch has been demonstrated to cause lissencephaly, a congenital disorder."

According to Etsuko Muto, who led the research team, "In the future, we hope that further understanding the interplay between dynein and microtubule, as this could pave the way for therapies for these conditions."

Media Contact

Jens Wilkinson
jens.wilkinson@riken.jp
81-048-462-1225

 @riken_en

http://www.riken.jp/en/

Jens Wilkinson | EurekAlert!

Further reports about: RIKEN Uchimura activation dynein hydrolysis kinesin microtubule microtubules molecular motor proteins

More articles from Life Sciences:

nachricht Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown University

nachricht Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017
25.04.2017 | Laser Zentrum Hannover e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>