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Dramatic 3D images reveal super-small motors that drive bacteria

by • March 29, 2016 • No Comments

When you want to get together with friends or family, chances are you employ a motor. That is to say, you most likely get into a car or on a few form of public transport to arrive at a meeting point. Bacteria really aren’t really different types of. They have different types of means of getting around, but they all involve a few kind of biological motor — and those motors have only been imaged in dramatic and colorful 3D by researchers at the California Institute of Technology (Caltech).

  • The engine that drives the flagellum of the Campylobactor bacteria, the most common bacteria that cause ...
  • A Lego model of a flagellum (top) and the motor that drives it (below)
  • The motor that powers the flagellum in the well-known Salmonella bacteria
  • This image shows a closeup of the motor that turns the tail of a Vibro bacterium, ...

To image the micromotors, the team employed a technique known as electron cyrotomography. This involves freezing bacterial cells so rapidly that the water molecules they contain don’t have the time to arrange themselves into ice crystals. Once the cells are locked in their original structure this way, an electron microscope was utilized to take a bunch of 2D images that were and so assembled in such a way that digital 3D images of the motors emerged. The technique was revolutionary, with Caltech reporting that it was the initially time bacteria’s biological locomotion machinery has ereally been imaged in 3D.

“Bacteria are widely considered to be ‘simple’ cells; yet, this assumption is a reflection of our limitations, not theirs,” says Grant Jensen, a Caltech professor of biophysics and biology. “In the past, we just didn’t have innovation that may reveal the full glory of the nanomachines – massive complexes comprising most copies of a dozen or additional one-of-a-kind proteins – that carry out sophisticated functions.”

Working with colleagues in the US, UK and Germost, Jensen and his team imaged two different types of kinds of bacterial motors.

The initially, reported in the March 11 issue of Science, was of a soil bacteria known as Myxococcus xanthus and is called the type IVa pilus machine (T4PM). This mechanism lets bacteria move by sending out a long fiber called the pilus. This fiber attaches to a surface and and so the bacterial reels itself forward along the tether.

To unravel the satisfactory details of this mechanism, the researchers created a series of mutant cells, every lacking a different types of component of the T4PM, that they and so compared to the intact bacteria so they may map the mechanism. In their observations, they found that the T4PM consists of four interconnected rings. They in addition found that it is actually really powerful.

“In this study, we announced the attractive complexity of this machine that may be the strongest motor known in nature. The machine lets M. xanthus, a predatory bacterium, move across a field to form a ‘wolf pack’ with other M. xanthus cells, and hunt together for other bacteria on that to prey,” Jensen says.

The 2nd biological motor that was imaged by the Caltech team involved one that drives the flagellum — a tiny whip-like propellor — that they observed in several different types of bacteria.

They found that there are motors within the bacteria created of proteins that turn the flagellum. What is additional, these protein structures were frequently found really far of the flagellum, that means they may generate worthwhile torque. It’s kind of like a tiny rotor on a fishing boat, versus a sizeable one on a yacht. Their work with the flagellum motors was published in the March 29 issue of the journal PNAS.

“These two studies establish a technique for solving the achieve structures of sizeable macromolecular complexes in situ, or within intact cells,” Jensen says. “Our electron cryotomography technique is a great solution for the reason it can be utilized to appear at the whole cell, providing a achieve picture of the architecture and location of these structures.”

To see precisely how pili assist move bacteria along with their motor-powered grappling-hook method, check out this video.

Source: Caltech


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