Nav: Home

How nature engineered the original rotary motor

April 13, 2017

The bacterial flagellum is one of nature's smallest motors, rotating at up to 60,000 revolutions per minute. To function properly and propel the bacterium, the flagellum requires all of its components to fit together to exacting measurements. In a study published today in Science, University of Utah researchers report the eludication of a mechanism that regulates the length of the flagellum's 25 nanometer driveshaft-like rod and answers a long-standing question about how cells are held together.

While the biomechanical controls that determine the dimensions of other flagellar components have already been determined, the control of the length of the rod, a rigid shaft that transfers torque from the flagellar motor in the interior of the cell to the external propeller filament, were unknown. "Since the majority of the machine is assembled outside the cell there have to be mechanisms for self-assembly and also to determine optimal lengths of different components," says biology professor Kelly Hughes. "How does it do that?"

Hughes' graduate student Eli Cohen pursued the question of rod length control in Salmonella enterica using genetic tools with slow progress until, in one of his courses, he heard about the concept of the outer membrane tethering protein Lpp, that physically links the outer membrane to the cell wall. The Salmonella envelope is composed of an inner membrane and an outer membrane that interacts with the outside world. Between the two membranes is a space containing a cell wall called the periplasm. Cell biologists previously didn't know whether the LppA protein propped up the cell wall, like pillars prop up a roof, or whether the outer membrane was tethered to the cell wall.

Cohen, Hughes, and their colleagues engineered strains of Salmonella to determine if LppA acted as a tether for the outer membrane and whether or not the outer membrane influenced flagellar rod length. They found that varying the length of the LppA protein varied the width of the periplasm along with the length of the rod.

"The rod needs to touch the inside of the outer membrane," Cohen says. "So, if the outer membrane is farther away, the rod has to grow there to meet it."

"This work ended up showing that it actually is a tether holding the outer membrane down," Hughes adds. "If you don't tether it down, the outer membrane explodes away from the cell."

Because the flagellum is tied to a bacteria's ability to move, an understanding of the controls on the flagellar system could help researchers learn how to immobilize harmful bacteria, and to hamper the flagellum-like systems that some bacteria use to infect host cells.
-end-
After the embargo lifts, the paper's DOI will be 10.1126/science.aam6512.

University of Utah

Related Bacteria Articles:

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.
How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.
The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?
Detecting bacteria in space
A new genomic approach provides a glimpse into the diverse bacterial ecosystem on the International Space Station.
Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.
Bacteria uses viral weapon against other bacteria
Bacterial cells use both a virus -- traditionally thought to be an enemy -- and a prehistoric viral protein to kill other bacteria that competes with it for food according to an international team of researchers who believe this has potential implications for future infectious disease treatment.
Drug diversity in bacteria
Bacteria produce a cocktail of various bioactive natural products in order to survive in hostile environments with competing (micro)organisms.
Bacteria walk (a bit) like we do
EPFL biophysicists have been able to directly study the way bacteria move on surfaces, revealing a molecular machinery reminiscent of motor reflexes.
Using bacteria to create a water filter that kills bacteria
Engineers have created a bacteria-filtering membrane using graphene oxide and bacterial nanocellulose.
Probiotics are not always 'good bacteria'
Researchers from the Cockrell School of Engineering were able to shed light on a part of the human body - the digestive system -- where many questions remain unanswered.
More Bacteria News and Bacteria Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#542 Climate Doomsday
Have you heard? Climate change. We did it. And it's bad. It's going to be worse. We are already suffering the effects of it in many ways. How should we TALK about the dangers we are facing, though? Should we get people good and scared? Or give them hope? Or both? Host Bethany Brookshire talks with David Wallace-Wells and Sheril Kirschenbaum to find out. This episode is hosted by Bethany Brookshire, science writer from Science News. Related links: Why Climate Disasters Might Not Boost Public Engagement on Climate Change on The New York Times by Andrew Revkin The other kind...
Now Playing: Radiolab

Breaking Bongo
Deep fake videos have the potential to make it impossible to sort fact from fiction. And some have argued that this blackhole of doubt will eventually send truth itself into a death spiral. But a series of recent events in the small African nation of Gabon suggest it's already happening.  Today, we follow a ragtag group of freedom fighters as they troll Gabon's president - Ali Bongo - from afar. Using tweets, videos and the uncertainty they can carry, these insurgents test the limits of using truth to create political change and, confusingly, force us to ask: Can fake news be used for good? This episode was reported and produced by Simon Adler. Support Radiolab today at Radiolab.org/donate.