An April 23, 2015 news item on Nanowerk calls to mind Monty Python and its Ministry of Silly Walks,
The ‘stiff-legged’ walk of a motor protein along a tightrope-like filament has been captured for the first time.
Because cells are divided in many parts that serve different functions some cellular goodies need to be transported from one part of the cell to another for it to function smoothly. There is an entire class of proteins called ‘molecular motors’, such as myosin 5, that specialise in transporting cargo using chemical energy as fuel.
Remarkably, these proteins not only function like nano-scale lorries, they also look like a two-legged creature that takes very small steps. But exactly how Myosin 5 did this was unclear.
For anyone unfamiliar with The Ministry of Silly Walks (from its Wikipedia entry; Note: Links have been removed),
“The Ministry of Silly Walks” is a sketch from the Monty Python comedy troupe’s television show Monty Python’s Flying Circus, season 2, episode 14, which is entitled “Face the Press”.
Here’s an image from the sketch, which perfectly illustrates a stiff-legged walk,As far as I can tell, the use of this image would fall under the notion of ‘fair dealing‘ as it’s called in Canada.
Getting back to the Nanowerk news item, it started life as a University of Oxford Science blog April 23, 2015 posting by Pete Wilton (Note: A link has been removed),
The motion of myosin 5 has now been recorded by a team led by Oxford University scientists using a new microscopy technique that can ‘see’ tiny steps of tens of nanometres captured at up to 1000 frames per second. The findings are of interest for anyone trying to understand the basis of cellular function but could also help efforts aimed at designing efficient nanomachines.
‘Until now, we believed that the sort of movements or steps these proteins made were random and free-flowing because none of the experiments suggested otherwise,’ said Philipp Kukura of Oxford University’s Department of Chemistry who led the research recently reported in the journal eLife. ‘However, what we have shown is that the movements only appeared random; if you have the capability to watch the motion with sufficient speed and precision, a rigid walking pattern emerges.’
One of the key problems for those trying to capture proteins on a walkabout is that not only are these molecules small – with steps much smaller than the wavelength of light and therefore the resolution of most optical microscopes – but they are also move very quickly.
Philipp describes how the team had to move from the microscope equivalent of an iPhone camera to something more like the high speed cameras used to snap speeding bullets. Even with such precise equipment the team had to tag the ‘feet’ of the protein in order to precisely image its gait: one foot was tagged with a quantum dot, the other with a gold particle just 20 nanometres across. (Confusingly, technically speaking, these ‘feet’ are termed the ‘heads’ of the protein because they bind to the actin filament).
I recommend reading Wilton’s post in its entirety. Meanwhile, here’s a 12 secs. video illustrating the motor protein’s stiff-legged walk,
Here’s a link to and a citation for the paper,
Structural dynamics of myosin 5 during processive motion revealed by interferometric scattering microscopy by Joanna Andrecka, Jaime Ortega Arroyo, Yasuharu Takagi, Gabrielle de Wit, Adam Fineberg, Lachlan MacKinnon, Gavin Young, James R Sellers, & Philipp Kukura. eLife 2015;4:e05413 DOI: http://dx.doi.org/10.7554/eLife.05413Published March 6, 2015
This paper is open access.
As for silly walks, there is more than one version of the sketch with John Cleese on YouTube but I was particularly taken with this public homage which took place in Brno (Czech Republic) in Jan. 2013,