Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Molecular Motors Cooperate In Moving Cellular Cargo

Abstract:
Tiny movements of molecular motors seen

Molecular Motors Cooperate In Moving Cellular Cargo, Study Shows

Champaign, Ill | April 07, 2005

Researchers using an extremely fast and accurate imaging technique have shed light on the tiny movements of molecular motors that shuttle material within living cells. The motors cooperate in a delicate choreography of steps, rather than engaging in the brute-force tug of war many scientists had imagined.

"We discovered that two molecular motors - dynein and kinesin - do not compete for control, even though they want to move the same cargo in opposite directions," said Paul Selvin, a professor of physics at the University of Illinois at Urbana-Champaign and corresponding author of a paper to appear in the journal Science, as part of the Science Express Web site, on April 7. "We also found that multiple motors can work in concert, producing more than 10 times the speed of individual motors measured outside the cell."

Dynein and kinesin are biomolecular motors that haul cargo from one part of a cell to another. Dynein moves material from the cell membrane to the nucleus; kinesin moves material from the cell nucleus to the cell membrane. The little cargo transporters accomplish their task by stepping along filaments called microtubules.

To measure such minuscule motion, Selvin and colleagues at Illinois developed a technique called Fluorescence Imaging with One Nanometer Accuracy (FIONA). The technique can locate a fluorescent dye 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). Recent improvements to FIONA now allow scientists to detect motion with millisecond time resolution.

Selvin's team used FIONA to track fluorescently labeled peroxisomes (organelles that break down toxic substances) inside specially cultured fruit fly cells. This was the first time the imaging technique had been used inside a living cell.

"Our measurements show that both dynein and kinesin carry the peroxisomes in a step-by-step fashion, moving about 8 nanometers per step," said Selvin, who also is a researcher at the Frederick Seitz Materials Research Laboratory on the Illinois campus.

"Because we see a fairly constant step size, we don't believe a tug of war is occurring," Selvin said. "If the dynein was fighting the kinesin, we would expect to see a lot of smaller steps as well."

The researchers also noted that faster movements occurred with the same step size, but with greater rapidity. When measured outside the cell, kinesin moved about 0.5 microns per second. Inside the cell, the speed increased to 12 microns per second.

"There must be a mechanism that allows the peroxisomes to move by multiple motors much faster than independent, uncoupled kinesins and dyneins," Selvin said. "It appears that motors are somehow regulated, being turned on or off in a fashion that prevents them from simultaneously dragging the peroxisome."

In the future, Selvin wants to combine FIONA and an optical trap technique to monitor the speed and direction of a peroxisome, and the force acting upon it.

"By measuring force we can determine how many molecular motors are working together," Selvin said. "This will help us further understand these marvelous little machines."

Collaborators on the study included Illinois graduate students Comert Kural and Hwajin Kim (lead authors), Illinois professor of cell and structural biology Vladimir Gelfand (now at the Northwestern University School of Medicine) and postdoctoral research associates Sheyum Syed at Illinois and Gohta Goshima at the University of California at San Francisco.

The work was funded by the National Institutes of Health, the National Science Foundation, and the U.S. Department of Energy.

####


Contact:
James E. Kloeppel
Physical Sciences Editor 217-244-1073
kloeppel@uiuc.edu

Copyright University of Illinois at Urbana-Champaign

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

Possible Futures

Argon is not the 'dope' for metallic hydrogen March 24th, 2017

Promising results obtained with a new electrocatalyst that reduces the need for platinum: Researchers from Aalto University have succeeded in manufacturing electrocatalysts used for storing electric energy with one-hundredth of the amount of platinum that is usually needed March 24th, 2017

Rice U. refines filters for greener natural gas: New study defines best materials for carbon capture, methane selectivity March 23rd, 2017

Artificial photosynthesis steps into the light: Rice University lab turns transition metals into practical catalyst for solar, other applications March 23rd, 2017

Molecular Machines

First 3-D observation of nanomachines working inside cells: Researchers headed by IRB Barcelona combine genetic engineering, super-resolution microscopy and biocomputation to allow them to see in 3-D the protein machinery inside living cells January 27th, 2017

Micro-bubbles make big impact: Research team develops new ultrasound-powered actuator to develop micro robot November 25th, 2016

Scientists come up with light-driven motors to power nanorobots of the future: Researchers from Russia and Ukraine propose a nanosized motor controlled by a laser with potential applications across the natural sciences and medicine November 11th, 2016

HKU chemists develop world's first light-seeking synthetic Nanorobot November 9th, 2016

Announcements

Argon is not the 'dope' for metallic hydrogen March 24th, 2017

Promising results obtained with a new electrocatalyst that reduces the need for platinum: Researchers from Aalto University have succeeded in manufacturing electrocatalysts used for storing electric energy with one-hundredth of the amount of platinum that is usually needed March 24th, 2017

Rice U. refines filters for greener natural gas: New study defines best materials for carbon capture, methane selectivity March 23rd, 2017

Artificial photosynthesis steps into the light: Rice University lab turns transition metals into practical catalyst for solar, other applications March 23rd, 2017

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