Stick and slide: Computer simulation advances understanding of molecular motors

Dec 02, 2009

A new study reveals how molecular motors that power important subcellular movements can generate cyclical motion. The research, published by Cell Press in the December issue of the Biophysical Journal, opens a new door to understanding motor molecules by using a computer program that faithfully simulates movement of hair-like cellular projections.

Many cells and single-celled organisms have tiny appendages called cilia and flagella that can wave or oscillate to move fluid across the cell surface or propel the cell forward. Each flagellum (or cilium) has nine pairs of fused microtubules, called outer doublets, arranged in a cylinder. Thousands of motor protein molecules, called dyneins, are arranged along each doublet. Each dynein motor attaches and detaches to the neighboring doublet, causing a sliding motion between the doublets, which causes oscillatory bending of the flagellum.

"We do not understand how the action of these motors is coordinated to produce useful bending patterns. In particular, the fundamental mechanism that generates oscillation has not been established," says study author Dr. Charles J. Brokaw from the Division of Biology at the California Institute of Technology. "The theories that have been proposed are difficult to test because of the complex structure of flagella."

Earlier studies in the laboratory of Dr. Ritsu Kamiya at the University of Tokyo used partially disintegrated flagella from and provided the first clear mechanism of a dynein-driven oscillation. Specifically, dyneins generated sliding forces that caused a lone pair of doublets to split apart near their bottom ends, which were still firmly attached together. Further sliding enlarged the separation and caused it to extend to the full length of the doublet pair, until it was completely dissociated. The doublets then reassociated, starting at their basal ends, until the dyneins were able to reinitiate sliding and repeat the cycle.

To fully exploit this simplified model system, Dr. Brokaw developed a computer program that could compute the movement of a doublet pair resulting from realistic dynein forces. The simulation confirmed what was inferred from the earlier study, that dynein-driven sliding is turned off when the separation between the doublets becomes too large, and is turned on again when the doublets reassociate.

"Perhaps more importantly, the new simulation demonstrated that dyneins must produce an adhesive force that keeps the doublets close together to produce sliding forces," explains Dr. Brokaw. "This first step will lead to programs in which ideas about the detailed chemical kinetics and structural mechanics of individual dyneins can be tested as the source of the sliding and adhesive forces."

Source: Cell Press (news : web)

Explore further: Research reveals evolution of cells' signaling networks in diverse organisms

add to favorites email to friend print save as pdf

Related Stories

Researchers shake up scientific theory on motor protein

Feb 05, 2009

( -- An international team of scientists led by the University of Leeds has shed new light on the little-understood motor protein called dynein, thought to be involved in progressive neurological ...

Molecular motors and brakes work together in cells

Jan 30, 2007

Researchers at the University of Pennsylvania School of Medicine have discovered that microtubules -- components responsible for shape, movement, and replication within cells -- use proteins that act as molecular ...

How a Cell's Mitotic Motors Direct Key Life Processes

Feb 02, 2009

University of Massachusetts Amherst biologists have discovered a secret of how cells organize chromosomes to prepare for dividing. Their unexpected finding is reported in this week’s issue of the journal, Current Biology.

Recommended for you

For resetting circadian rhythms, neural cooperation is key

18 hours ago

Fruit flies are pretty predictable when it comes to scheduling their days, with peaks of activity at dawn and dusk and rest times in between. Now, researchers reporting in the Cell Press journal Cell Reports on April 17th h ...

Rapid and accurate mRNA detection in plant tissues

19 hours ago

Gene expression is the process whereby the genetic information of DNA is used to manufacture functional products, such as proteins, which have numerous different functions in living organisms. Messenger RNA (mRNA) serves ...

For cells, internal stress leads to unique shapes

Apr 16, 2014

From far away, the top of a leaf looks like one seamless surface; however, up close, that smooth exterior is actually made up of a patchwork of cells in a variety of shapes and sizes. Interested in how these ...

User comments : 0

More news stories

Scientists tether lionfish to Cayman reefs

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.

Deadly human pathogen Cryptococcus fully sequenced

Within each strand of DNA lies the blueprint for building an organism, along with the keys to its evolution and survival. These genetic instructions can give valuable insight into why pathogens like Cryptococcus ne ...

Leeches help save woman's ear after pit bull mauling

(HealthDay)—A pit bull attack in July 2013 left a 19-year-old woman with her left ear ripped from her head, leaving an open wound. After preserving the ear, the surgical team started with a reconnection ...

Venture investments jump to $9.5B in 1Q

Funding for U.S. startup companies soared 57 percent in the first quarter to a level not seen since 2001, as venture capitalists piled more money into an increasing number of deals, according to a report due out Friday.