Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bacterial Nanosized Speargun Works Like a Power Drill

26.09.2017

In order to get rid of unpleasant competitors, some bacteria use a sophisticated weapon – a nanosized speargun. Researchers at the University of Basel’s Biozentrum have now gained new insights into the construction, mode of action and recycling of this weapon. As they report in the journal “Nature Microbiology”, the speargun drills a hole into the neighboring cells in only a few thousandths of a second and injects a cocktail of toxins.

Millions of tiny microbes on leaves, stones or our skin jostle for space. And almost everywhere they have to compete for resources and nutrients. In the course of evolution, some bacteria have therefore developed a weapon to inject a toxic cocktail into competitors and rivals in their neighborhood, thus eliminating them. Among experts, this weapon resembling a speargun is also known as the type VI secretion system (T6SS).


Structure of the bacterial nanosized speargun – called type VI secretion system – during contraction.

University of Basel, Biozentrum

Two years ago, Prof. Marek Basler was able to elucidate the atomic structure of the speargun in the “post-firing” state. In the current study, which was carried out in cooperation with various research groups and technology platforms at the Biozentrum, his team has now solved the structure of the “ready to fire” speargun. Based on these findings, the researchers have been able to model how this T6SS speargun works.

Structure of nanosized speargun changes during firing

The speargun is composed of various components, including a sheath and a spear with a sharp tip. The sheath consists of over 200 connected cogwheel-like protein rings that are assembled around the inner rigid spear. When T6SS fires, the sheath rapidly contracts and pushes the toxic spear out of the cell, which can then penetrate into neighboring cells where it releases deadly toxins. “So far, there have only been assumptions as to how the structure of the T6SS sheath changes during contraction,” says Basler. “Using cryo-electron microscopy available at C-CINA, we have now obtained an image of the spear and the extended sheath in atomic resolution.”

By comparing the structures of the extended and contracted states, the researchers were able to model how the T6SS works in detail. “During the sheath contraction, ring after ring turns and gets closer to the previous ring, while the ring diameter expands and thus releases the spear,” explains Basler. “This combination of sheath shrinking and turning results in drilling a hole into the target cells. Within less than two milliseconds, the T6SS sheath contracts to half of its length and at the same time the toxic spear spirals out like a screw. Therefore, the bacteria have an extremely powerful drill.”

Only contracted T6SS sheaths are disassembled

Furthermore, the researchers also addressed another question. After firing T6SS, bacteria re-use the individual components of the sheath to assemble a new speargun. “For a long time, it was not clear why only the contracted, but not the extended sheath is disassembled,” says Basler. “Now, we could see that a certain protein domain is exposed on the surface of the sheath during contraction and can be recognized by a specific protein responsible for dismantling the sheath. In the extended sheath state, this domain is hidden and the T6SS sheath is therefore protected from disassembly.”

The bacterial speargun will continue to be the subject of future research. “One of our projects is dedicated to the question of how the T6SS is embedded in the bacterial cell envelope. As the speargun is fired with such a high force, it must be firmly anchored, otherwise firing would not work properly or could be also fatal for the weapon-carrying bacteria themselves.”

Original article

Jing Wang, Maximilian Brackmann, Daniel Castaño-Díez, Mikhail Kudryashev, Kenneth N. Goldie, Timm Maier, Henning Stahlberg and Marek Basler
Cryo-EM structure of the extended type VI secretion system sheath-tube complex
Nature Microbiology (2017), doi: 10.1038/s41564-017-0020-7

Video: Prof. Marek Basler, Bacterial nanosized speargun

https://www.youtube.com/watch?v=wrGOU76fg40

Further information

Prof. Dr. Marek Basler, University of Basel, Biozentrum, Tel. +41 61 207 21 10, email: marek.basler@unibas.ch
Dr. Katrin Bühler, University of Basel, Biozentrum, Communications, Tel. +41 61 207 09 74, email: katrin.buehler@unibas.ch

Dr. Katrin Bühler | Universität Basel
Further information:
http://www.unibas.ch

More articles from Life Sciences:

nachricht More genes are active in high-performance maize
19.01.2018 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht How plants see light
19.01.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Let the good tubes roll

19.01.2018 | Materials Sciences

How cancer metastasis happens: Researchers reveal a key mechanism

19.01.2018 | Health and Medicine

Meteoritic stardust unlocks timing of supernova dust formation

19.01.2018 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>