One step at a time: Motor molecules use random walks to make deliveries in living cells

Jul 21, 2009

Cells rely on tiny molecular motors to deliver cargo, such as mRNA and organelles, within the cell. The critical nature of this transport system is evidenced by the fact that disruption of motors by genetic defects leads to fatal diseases in humans. Although investigators have isolated these motor to study their function in a controlled environment outside the cell, it has been difficult for researchers to follow these fascinating molecular transporters in their natural environment, the living cell.

Now, two articles published by Cell Press in , make use of incredibly tiny, glowing "quantum dots" to track the miniscule motions of myosin V in living cells. Interestingly, both research groups independently report that myosin V molecules carry their quantum dot cargo either in a straight line or in a manner akin to a drunken walk.

Myosin V is a motor molecule that "walks" in a fashion similar to humans by stepping along actin filament tracks that are assembled in a dense, criss-crossing network inside the cell. A critical feature of these motors is their ability to walk long distances without falling off their tracks. However, this has never been observed within cells. Through the binding of quantum dots directly to a single myosin V molecule, both investigative teams used sophisticated microscopes and sensitive cameras to witness the 72 nanometer strides (equivalent to 1 millionth of an inch) taken by these motors for the first time in cells.

In results published in the May 20th 2009 issue of Biophysical Journal, Dr. Giovanni Cappello from the Institut Curie in Paris, France tracked the movement of single myosin V molecules with inside living HeLa cells. Dr. Cappello and colleagues reported that the myosin V can transport cargo for long distances without falling off its track at velocities higher than would be expected based on earlier studies. "Our approach goes beyond conventional experiments on organelles and opens interesting perspectives for studying intracellular transport pathways and how motors behave in complex filament networks," says Dr. Cappello.

Dr. David Warshaw and colleagues from the University of Vermont College of Medicine used to follow the activity of myosin V in COS-7 cells. Their findings, published in the July 22nd 2009 issue of the journal, suggested that myosin V's apparent drunken walk is in fact the motor taking turns at almost every intersection it encounters along the dense and randomly oriented intracellular actin highway. "Cargo delivery in cells can't totally be a random process, therefore, using the approach described here we can characterize how motors and cargo link up and understand the engineering design principles Mother Nature uses to guarantee efficient and effective delivery of cargo within cells," offers Dr. Warshaw.

Source: Cell Press (news : web)

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mabarker
1 / 5 (1) Jul 22, 2009
Just what is it going to take for darwinists to wake up and smell the coffee? It would be difficult to find a more overt signature of a Designer than what we are uncovering here. The rotary motor F-F ATPase consists of a rotor, cam, turbine and stator (I was a jet engine mechanic in the Navy and can appreciate such structures - I can asure you jet engines do not come about by chance) - see Rastogi in Nature 402 & FEBS Letters 545. Furthermore, the AcrA/AcrB/TolC complex is a rotary motor that operates as a literal molecular-level peristalic pump.
And wut about them fancy viral motors? See Simpson, et al, Nature 408 & Smith et al Nature 413. Genetic mistakes made these motors? No. And to say so is being very unscientific.
The author of the above article uses a classic phrase: *engineering design principles* - you only get EDP from The Designer (Genesis 1) - not *mother nature*
Marquette
not rated yet Jul 22, 2009
This discovery in no way implies that an invisible Keebler Elf carved life from clay in his hollow tree. It does show that very simple molecules can perform complex actions. If your "designer" is so smart, why do the molecules move in a random walk pattern, rather than going directly to their target?

I agree scientists should avoid using language about "Mother Nature" and "engineering design principles" when describing biological structures, because it tends to be misinterpreted by overly literal-minded people.
mabarker
1 / 5 (1) Jul 22, 2009
Marc-et is your typical creation-hating darwinist who doesn't really read the article before making a hasty judgment. Myosin V has an *apparent* drunken walk according to the article. Further research will show why it moves in that manner. They move in a manner that gets the cargo to their target. Because they don't move in a human-centric manner causes evolutionists to play the *bad design* card. It's just like the *junk DNA* darwinists were screaming about years ago - why would The Creator design DNA that way, they whined. It has since been found that non-coding DNA isn't junk at all - as creationists predicted.

No where did I mention an elf, clay or tree - but hey - that's a good straw-man argument Mark-et. Where evolutionism fails, creation-bashing avails.

Marc-et says *simple molecules* but I don't find that phrase in the above article - nor in the ones I cited in my post above. Biomolecules are complex by their very nature, such as the AAA ring on the dynein molecule. Give me citations from science journals that document the formation of functional biomolecules (like the myosin linear motor) from random mutations. Good luck!
Ethelred
5 / 5 (1) Jul 28, 2009
Give me citations from science journals that document the formation of functional biomolecules (like the myosin linear motor) from random mutations. Good luck!


Ma refuses to get the concept. Mutations are random but selection is anything but random.

Just what is it going to take for darwinists to wake up and smell the coffee?


When are YOU going to go on the evidence and quit making bogus claims that evolution is dependent purely on randomness?

Further research will show why it moves in that manner. They move in a manner that gets the cargo to their target.


Perhaps. Perhaps a random walk is the best evolution has come up with.

Genetic mistakes made these motors? No. And to say so is being very unscientific.


Being unscientific is denying all the evidence that supports evolution and your consistent evasion of Natural Selection as the source of information that gained by evolution.

The author of the above article uses a classic phrase: *engineering design principles* - you only get EDP from The Designer (Genesis 1) - not *mother nature*


Some people just write sloppy. They don't deal with Creationists so they use sloppy terms. I know better the author clearly doesn't.

Other stupid or foolish terms in the paragraph:

Mother Nature uses to guarantee efficient and effective delivery of cargo within cells


There is no Mother Nature nor is there is any guarantee of efficiency. For that matter the walk is most likely NOT random. That is, I bet it never goes in reverse.

t has since been found that non-coding DNA isn't junk at all - as creationists predicted.


So did I and before I ever saw a Creationist predict such a thing. Indeed I still haven't seen any evidence that a Creationist predicted it. I knew that SOMETHING had to code for the ribosomes for one thing. This sort of thinking came from an overemphasis on proteins.

As for Genesis there is NO evidence to support Genesis 1 AND Genesis 2 contradicts Genesis 1. Neither chapters of Genesis fits the evidence in any case.

That's the first time I caught you admitting that your ideas are purely religious. Prior to this you have steadfastly followed the Discovery Institutes preferred mode of inventing controversy from out of context quotes.

What a give away.

Ethelred