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 Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care

nachricht Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>