Featured Research

from universities, journals, and other organizations

Molecular Motor Myosin VI Moves 'Hand Over Hand,' Researchers Say

Date:
September 3, 2004
Source:
University Of Illinois At Urbana-Champaign
Summary:
In the human body, hundreds of different types of biomolecular motors help carry out such essential tasks as muscle contraction, moving chromosomes during cell division, and reloading nerve cells so they can repeatedly fire. How these little proteins perform their duties is becoming clearer to scientists using an extremely sensitive measurement technique.

Myosin VI (blue) is a molecular motor that walks "backwards" on filaments of actin (red). By labeling a myosin VI on the head (green), or on the neck (red), and localizing the dye within a few nanometers, scientists determined that myosin walks "hand-over-hand," while causing a part of the protein to come undone. (Graphic courtesy Paul Selvin)

CHAMPAIGN, Ill. — In the human body, hundreds of different types of biomolecular motors help carry out such essential tasks as muscle contraction, moving chromosomes during cell division, and reloading nerve cells so they can repeatedly fire.

How these little proteins perform their duties is becoming clearer to scientists using an extremely sensitive measurement technique. Myosin VI, they found, moves by the same “hand-over-hand” mechanism as two other molecular motors, myosin V and kinesin.

“Now that a third molecular motor has been found to move in the same hand-over-hand fashion, the argument for a rival ‘inchworm’ motion is getting pretty weak,” said Paul Selvin, a professor of physics at the University of Illinois at Urbana-Champaign and a co-author of a paper to appear in the Journal of Biological Chemistry.

Myosin VI is a reverse-direction molecular motor that moves materials to various locations within a living cell. Like the related protein myosin V, myosin VI has two “arms” connected to a “body.” The tiny molecule converts chemical energy into mechanical motion, and transports its load by “stepping” along polarized filaments of actin – but in the opposite direction from other myosin variants.

“Studies have suggested two main models for the stepping movement,” Selvin said. “One is the hand-over-hand model in which the two arms alternate in the lead. The other model is the inchworm model in which one arm always leads.”

To examine the myosin VI stepping mechanism, the researchers applied the same technique that was used to study both myosin V and kinesin. Called FIONA – Fluorescence Imaging with One Nanometer Accuracy – the measurement technique can track the position of a single molecule to within 1.5 nanometers. (One nanometer is a billionth of a meter, or about 10,000 times smaller than the width of a human hair).

“First, we attached a small fluorescent dye to one of the arms and took a picture with a digital camera attached to a microscope to find exactly where the dye was,” Selvin said. “Then we fed the myosin a little food called adenosine triphosphate, and it took a step. We took another picture, located the dye, and measured how far the dye moved.”

By examining the step size, the scientists could determine whether the protein used a hand-over-hand mechanism or an inchworm mechanism for movement. “The average step size for the myosin VI arm was approximately 60 nanometers, while the molecule’s center of mass moved only half that distance,” Selvin said. “This clearly indicated that a hand-over-hand model was being employed.”

Surprisingly, myosin VI has a step size that is highly variable, but on average is nearly as large as that of myosin V, which has a lever arm that is three times longer.

“For myosin VI to reach the same distance, the molecule must somehow come apart and then snap together again,” Selvin said. “To understand how it accomplishes this feat will require further study.”

The co-authors of the paper are Selvin, Hyokeun Park and Ahmet Yildiz at Illinois, and Li-Qiong Chen, Dan Safer, H. Lee Sweeney and Zhaohui Yang at the University of Pennsylvania. The National Institutes of Health funded the work.


Story Source:

The above story is based on materials provided by University Of Illinois At Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Urbana-Champaign. "Molecular Motor Myosin VI Moves 'Hand Over Hand,' Researchers Say." ScienceDaily. ScienceDaily, 3 September 2004. <www.sciencedaily.com/releases/2004/09/040901091750.htm>.
University Of Illinois At Urbana-Champaign. (2004, September 3). Molecular Motor Myosin VI Moves 'Hand Over Hand,' Researchers Say. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2004/09/040901091750.htm
University Of Illinois At Urbana-Champaign. "Molecular Motor Myosin VI Moves 'Hand Over Hand,' Researchers Say." ScienceDaily. www.sciencedaily.com/releases/2004/09/040901091750.htm (accessed October 23, 2014).

Share This



More Matter & Energy News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

3D Printed Instruments Make Sweet Music in Sweden

3D Printed Instruments Make Sweet Music in Sweden

Reuters - Innovations Video Online (Oct. 23, 2014) Students from Lund University's Malmo Academy of Music are believed to be the world's first band to all use 3D printed instruments. The guitar, bass guitar, keyboard and drums were built by Olaf Diegel, professor of product development, who says 3D printing allows musicians to design an instrument to their exact specifications. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Jet Sales Lift Boeing Profit 18 Pct.

Jet Sales Lift Boeing Profit 18 Pct.

Reuters - Business Video Online (Oct. 22, 2014) Strong jet demand has pushed Boeing to raise its profit forecast for the third time, but analysts were disappointed by its small cash flow. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Internet of Things Aims to Smarten Your Life

Internet of Things Aims to Smarten Your Life

AP (Oct. 22, 2014) As more and more Bluetooth-enabled devices are reaching consumers, developers are busy connecting them together as part of the Internet of Things. (Oct. 22) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins