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 August 27, 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 August 27, 2014).

Share This




More Matter & Energy News

Wednesday, August 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Australian Airlines Relax Phone Ban Too

Australian Airlines Relax Phone Ban Too

Reuters - Business Video Online (Aug. 26, 2014) Qantas and Virgin say passengers can use their smartphones and tablets throughout flights after a regulator relaxed a ban on electronic devices during take-off and landing. As Hayley Platt reports the move comes as the two domestic rivals are expected to post annual net losses later this week. Video provided by Reuters
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Chinese Researchers Might Be Creating Supersonic Submarine

Chinese Researchers Might Be Creating Supersonic Submarine

Newsy (Aug. 26, 2014) Chinese researchers have expanded on Cold War-era tech and are closer to building a submarine that could reach the speed of sound. Video provided by Newsy
Powered by NewsLook.com
Breakingviews: India Coal Strained by Supreme Court Ruling

Breakingviews: India Coal Strained by Supreme Court Ruling

Reuters - Business Video Online (Aug. 26, 2014) An acute coal shortage is likely to be aggravated as India's supreme court declared government coal allocations illegal, says Breakingviews' Peter Thal Larsen. Video provided by Reuters
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:
from the past week

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