Featured Research

from universities, journals, and other organizations

Some motor proteins cooperate better than others

Date:
January 9, 2014
Source:
Rice University
Summary:
A study analyzes how teams of molecular motor proteins cooperate as they move cargoes around living cells.

Rice University researchers have engineered cells to characterize how sensitively altering the cooperative functions of motor proteins can regulate the transport of organelles.

The study, by the Rice lab of bioengineer and chemist Michael Diehl, compared the collective behaviors of kinesin-1 and myosinVa in living cells to determine how these motor proteins cooperate as they move vesicles and organelles along intracellular highways formed from cytoskeletal filaments. These transport processes are critical to numerous developmental and signaling functions within cells, and breakdowns in motor functions are also implicated in several human diseases.

The work appears this week in the Proceedings of the National Academy of Sciences.

Diehl and his colleagues at Rice's BioScience Research Collaborative, including Rice postdoctoral researchers Anand Radhakrishan and Artem Efremov and graduate student David Tsao, compared the collective responses of the motor proteins to variations in motor numbers and cargo sizes.

They began with a good understanding of the collective pulling power of kinesin motors. Kinesin is a type of protein that binds to and transports cargoes by walking along cytoskeletal filaments called "microtubules." In previous experiments, they engineered multiple motor systems that were anchored to polystyrene beads as an experimental cargo, but this time decided to engineer organelles called "peroxisomes" within living cells for these analyses.

"Our earlier work was detailed and very precise, but the central limitation was simply that the motors were not transporting a real cargo," Diehl said. In contrast to rigid beads, many organelles like peroxisomes have fluid-like lipid membranes. Motors attached to their surfaces will therefore interact in ways that are difficult to recapitulate using plastic beads.

"The physical environment inside a living cell is also difficult to emulate during in-vitro experiments," he said. "This could also have an appreciable impact on how motors cooperate to transport their cargoes."

Using genetically engineered COS cells, the team coupled motor proteins to peroxisomes via a certain type of protein switch. They regulated the expression of these protein switch genes in combination with a second gene that allowed them to tune the final density of motors on the surfaces of peroxisomes as well as the distributions of peroxisome sizes.

The genetic-level controls allowed the group to evaluate how the collective behaviors of kinesin and myosinVa motors responded to changes in motor levels and size-dependent forces imposed on the peroxisomes by the cytoplasm. In contrast to behaviors found for kinesins, they show that the cargoes move more rapidly when myosinVa levels are altered and that myosin systems are more readily capable of producing the forces necessary to propel large cargos in living cells.

"Kinesins are like racehorses that basically only know how to run fast," Diehl said. "They don't like to work together in teams to transport cargos, and usually one kinesin is left doing the work of transporting a cargo on its own. MyosinVa motors, however, are more like stagecoach horses. If you add more horses, you get more force production. You get more speed. This distinction is important, since it suggests that collective functions of myosinVa can be regulated more sensitively than kinesins."

Kinesin and myosinVa are bound simultaneously to the surfaces of many organelles, Diehl said. The collective force-producing capacities and responses of cargo transport to variation in motor copy number will influence the trafficking of cargoes to different regions of cells. "Cells needs to be able to regulate that competition, and so it may be useful to have one motor, kinesin, that's strong individually but not capable of cooperating, and another motor that might be weak individually but have a strong cooperative effect," he said. "It means all the fine tuning can take place on one side."

The overall results open a new window into cellular mechanisms, Diehl said. "Now that we're able to probe detailed relationships between motor type, ratio, cargo size and force, we can start to examine more complicated collective and regulatory behaviors directly," he said. "We hope to recapitulate scenarios where multiple normal motors are bound to the surfaces of cargoes simultaneously with motor mutants that have been associated with neurodegenerative diseases. This way, we can precisely examine how these mutants perturb intracellular transport pathways."


Story Source:

The above story is based on materials provided by Rice University. Note: Materials may be edited for content and length.


Journal Reference:

  1. A. K. Efremov, A. Radhakrishnan, D. S. Tsao, C. S. Bookwalter, K. M. Trybus, M. R. Diehl. Delineating cooperative responses of processive motors in living cells. Proceedings of the National Academy of Sciences, 2014; DOI: 10.1073/pnas.1313569111

Cite This Page:

Rice University. "Some motor proteins cooperate better than others." ScienceDaily. ScienceDaily, 9 January 2014. <www.sciencedaily.com/releases/2014/01/140109180314.htm>.
Rice University. (2014, January 9). Some motor proteins cooperate better than others. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2014/01/140109180314.htm
Rice University. "Some motor proteins cooperate better than others." ScienceDaily. www.sciencedaily.com/releases/2014/01/140109180314.htm (accessed October 20, 2014).

Share This



More Plants & Animals News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

White Lion Cubs Born in Belgrade Zoo

White Lion Cubs Born in Belgrade Zoo

AFP (Oct. 20, 2014) Two white lion cubs, an extremely rare subspecies of the African lion, were recently born at Belgrade Zoo. They are being bottle fed by zoo keepers after they were rejected by their mother after birth. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
Goliath Spider Will Give You Nightmares

Goliath Spider Will Give You Nightmares

Buzz60 (Oct. 20, 2014) An entomologist stumbled upon a South American Goliath Birdeater. With a name like that, you know it's a terrifying creepy crawler. Sean Dowling (@SeanDowlingTV) has the details. Video provided by Buzz60
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
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


Plants & Animals

Earth & Climate

Fossils & Ruins

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