Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button


Home > Press > 'Prima donna' protein doesn't work well in pairs

Rice University bioengineers measure pulling power of hitched pairs of protein motors

'Prima donna' protein doesn't work well in pairs

Houston, TX | Posted on November 5th, 2010

A new study by Rice University bioengineers finds that the workhorse proteins that move cargo inside living cells behave like prima donnas. The protein, called kinesin, is a two-legged molecular machine. Rice's scientists invented tools that could measure the pulling power of kinesin both singly and in pairs, and they report this week in Biophysical Journal that kinesins don't work well together -- in part because they are so effective on their own.

"Researchers have been investigating the mechanical properties of individual motor proteins for some time now, but this is the first time anyone's been able to tie a defined number of molecular motors to a cargo and watch them work together," said lead researcher Michael Diehl, assistant professor in bioengineering at Rice. "We know that more than one of these motors is attached to most cargoes, so understanding how they work together -- or fail to -- is a key to better understanding the intracellular transport system."

Cargoes inside cells are hitched to teams of motor proteins and hauled from place to place like horse-drawn wagons. Like stagecoaches or wagons, many cargoes are pulled by several horses. But unlike a wagon, cellular cargoes often also have multiple teams pulling in opposite directions.
"Motor proteins move directionally," Diehl said. "They either move toward the cell's nucleus or they move away from the nucleus toward the periphery. Grouping different types of motors together allows cells to regulate cargo movement. But when there are multiple motors pulling antagonistically in opposite directions, what determines which group wins? What influences the balance? How do they cooperate or compete to get the right packages to the right place? Those are the kinds questions we're trying to answer."

Diehl said intracellular transport has become an increasingly hot topic over the past decade, in part because researchers have found that breakdowns in the transport system are linked to neurodegenerative diseases like amyotrophic lateral sclerosis (ALS) and Huntington's disease.

One question Diehl and lead co-authors Kenneth Jamison and Jonathan Driver helped answer in the new study is how much pulling power a pair of kinesins could apply to a cargo compared with the amount applied by a single kinesin.

The apparatus they created to study the problem was years in the making. Driver and Jamison, both graduate students, used strands of DNA to make a scaffold, a sort of molecular yoke that they could use to hitch a pair of kinesins to an experimental cargo. The cargo in their tests was a microscopic plastic bead. Using laser beams in an instrument called an optical trap, they attached teams of bead-pulling proteins to microtubule roadways.

As the motors walked down the road, they pulled the bead away from the center of the optical trap. At the same time, the lasers in the trap exerted counterpressure in an effort to move the bead back to the center of the trap. Eventually, the light won out, forcing the motors to let go and the cargo to snap back to the middle of the beam. By measuring the precise movements of the bead during this reaction, Diehl's team was able to determine exactly how much force a team of motors exerted on a bead.

"Compared with other motors, kinesin is actually a pretty strong performer," he said. "Single kinesin motor molecules can produce relatively large forces, and they rarely step in the wrong direction when walking along microtubules. This is remarkable behavior, considering kinesin is a molecular-scale machine that experiences significant thermal and chemical fluctuations."

Given how well they perform alone, it would be easy to assume that a group of kinesins would pull harder than a single kinesin. But Diehl points out that a team of kinesins can only harness the combined potential of both motors under certain circumstances.

"Our analyses show that the two kinesins must stay in close proximity to one another to cooperate effectively," he said. "Otherwise, one of the motors will tend to assume all of the applied force imposed on the cargo. Kinesin is relatively fast and efficient on its own, but they have trouble keeping up with one another when they are connected together."

Diehl said the group suspects that other classes of motor molecules, which are somewhat weaker than kinesin, may function better in groups. The team is carrying out follow-up experiments to see if that's the case, and they are examining how such distinctions may play a role in regulating cargo movement in cells.

Diehl's research group, which is located in Rice's new BioScience Research Collaborative, has spent years refining the tools used in the new study, and the work is paying off in numerous ways. Within the past four months, the group won an R01 grant from the National Institutes of Health worth more than $1.4 million, and Diehl also published a theoretical study of motor proteins with Rice chemist Anatoly Kolomeisky.

Diehl's research is funded by the National Institutes of Health, the National Science Foundation and the Welch Foundation.


About Rice University
Located in Houston, Rice University is consistently ranked one of America's best teaching and research universities. Known for its "unconventional wisdom," Rice is distinguished by its: size -- 3,279 undergraduates and 2,277 graduate students; selectivity -- 12 applicants for each place in the freshman class; resources -- an undergraduate student-to-faculty ratio of 5-to-1; sixth largest endowment per student among American private research universities; residential college system, which builds communities that are both close-knit and diverse; and collaborative culture, which crosses disciplines, integrates teaching and research, and intermingles undergraduate and graduate work.

For more information, please click here

Jade Boyd

Copyright © Rice University

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.

Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Scientists found a natural nanostructure to control the flow of light October 4th, 2015

Horizontal magnetic tunneling in a field-effect device integrated on Silicon October 3rd, 2015

Crystal clear: Thousand-fold fluorescence enhancement in an all-polymer thin film: Griffith University researchers report breakthrough due to novel and multi-layer Colloidal Photonic Crystal structure October 2nd, 2015

Industrial Nanotech, Inc. Announces New Office in Arizona to Service the Company's New Regional and National Home Builders in Arizona and Nevada October 2nd, 2015


Sniffing out cancer with improved 'electronic nose' sensors October 2nd, 2015

New Processes in Modern ReRAM Memory Cells Decoded October 1st, 2015

Researchers measure how specific atoms move in dielectric materials October 1st, 2015

Researchers create first entropy-stabilized complex oxide alloys September 30th, 2015


SUNY Poly Announces Joint Development Agreement with INFICON to Establish Cutting Edge R&D Partnership Supporting New York State’s Rapidly Expanding Nanoelectronics Industry September 23rd, 2015

Rice announces $150 million in strategic research initiatives: Plan includes campuswide investments, new hires in data science, nanotechnology September 22nd, 2015

A quantum lab for everyone: Modern science as a photorealistic online game September 17th, 2015

UO research dollars climbed in FY 2015: Buoyed by an uptick in federal awards, the university saw gains in its overall sponsored research funding and continued high proposal counts in 2014-2015 September 17th, 2015

Molecular Machines

Nanomachines: Pirouetting in the spotlight September 29th, 2015

Using DNA origami to build nanodevices of the future September 1st, 2015

Injectable electronics: New system holds promise for basic neuroscience, treatment of neuro-degenerative diseases June 8th, 2015

One step closer to a single-molecule device: Columbia Engineering researchers first to create a single-molecule diode -- the ultimate in miniaturization for electronic devices -- with potential for real-world applications May 25th, 2015


Scientists found a natural nanostructure to control the flow of light October 4th, 2015

Industrial Nanotech, Inc. Announces New Office in Arizona to Service the Company's New Regional and National Home Builders in Arizona and Nevada October 2nd, 2015

Production of High Temperature Ceramics with Modified Properties in Iran October 2nd, 2015

ISO Approves 2 Int'l Nanotechnology-Related Standards Proposed by Iran October 2nd, 2015


ISO Approves 2 Int'l Nanotechnology-Related Standards Proposed by Iran October 2nd, 2015

Rice news release: Smaller is better for nanotube analysis: Rice University's variance spectroscopy technique advances nanoparticle analysis September 30th, 2015

New Nanomaterials Taking Research to Mexico, Possibly into Space September 29th, 2015

Haydale Wins Major Research Grants September 26th, 2015

The latest news from around the world, FREE

  Premium Products
Only the news you want to read!
 Learn More
University Technology Transfer & Patents
 Learn More
Full-service, expert consulting
 Learn More

Nanotechnology Now Featured Books


The Hunger Project

Car Brands
Buy website traffic