Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How bacteria make syringes

14.06.2010
For a successful infection, bacteria must outwit the immune system of the host. To this aim, they deliver so-called virulence factors through a transport channel located in the bacterial membrane.
In some bacteria this transport channel is formed like a syringe, enabling them to inject virulence factors directly into the host cell. Scientists from the Max Planck Society and the Federal Institute for Materials Research and Testing have now succeeded for the first time in elucidating basic principles of the assembly of this transport channel. This is an important starting point for the development of new drugs that might interfere considerably earlier than antibiotics in the course of infection. (Nature Structural & Molecular Biology, 13 June 2010)

Every day the human organism is confronted with a huge variety of pathogens (fig. 1). Most of them are fended off by our immune system. To execute a successful infection, bacteria must therefore manipulate the host to ensure their survival. They secrete virulence factors through a transport channel located in the bacterial membrane. Some bacteria, such as the causative agents of dysentery, food poisoning, typhoid fever, and pest, have developed a specialized transport mechanism called the Type three secretion system. Electron microscopy reveals that this structure is formed like a syringe: the base of the syringe is imbedded in the bacterial membrane and the needle protrudes out of the bacteria (fig. 2). With this apparatus bacteria can inject virulence factors directly into the host cell.
So far, little has been known about how bacteria build this nano-syringe. Scientists from the Max Planck Institute for Infection Biology in Berlin, the Max Planck Institute for Biophysical Chemistry in Göttingen, and the Federal Institute for Materials Research and Testing have now succeeded in elucidating fundamental principles of the needle assembly. This was made possible by reconstitution experiments which allowed them to study the assembly of proteins into a needle in the test tube (fig. 3).

The close observation of these events revealed how the proteins are assembled into a syringe: the bacterium synthesizes the proteins in the cell interior, transports them through the syringe to the outside, and stacks them one after the other onto the tip of the growing needle. The scientists could also show that the proteins change their three-dimensional structure during the assembly process. They were able to pinpoint the exact structural changes down to the single amino acid level. These results open new perspectives in the development of medicines that might interfere in the course of infection much earlier than antibiotics. These so-called anti-infectives could inhibit the assembly of the needle and the injection of virulence factors into the host cell. This would be a major advantage over antibiotics, which have to travel through the membrane into the bacteria to be able to kill it. Furthermore, antibiotics cannot distinguish between good and evil, i.e. disease-causing, bacteria, often leading to unwanted side effects. Lastly, the use of anti-infectives would circumvent the problem of antibiotic resistance development.

Shigella flexneri, the causative agent of dysentery (orange), establishes contact with a human host cell (blue). The bar corresponds to a micrometer or a thousandth millimeter, respectively. Credit: Volker Brinkmann, Diane Schad, and Michael Kolbe


You can clearly see the two membranes (orange) enclosing the cell interior (blue) and the needles protruding to the outside (orange, marked in blue). The bar corresponds to a micrometer or a thousandth millimeter, respectively. Credit: Ulrike Abu Abed, Diane Schad, and Michael Kolbe

The change of the three-dimensional structure of the proteins during the needle assembly was analyzed by X-ray structural experiments at BESSY in Berlin and ESRF in Grenoble and NMR-spectroscopic experiments based on radio waves at the Max Planck Institute for Biophysical Chemistry. The scientists compared the three-dimensional structure of the needle protein before and after the needle assembly.

Original paper:
Ömer Poyraz, Holger Schmidt, Karsten Seidel, Friedmar Delissen, Christian Ader, Hezi Tenenboim, Christian Goosmann, Britta Laube, Andreas F. Thünemann, Arturo Zychlinsky, Marc Baldus, Adam Lange, Christian Griesinger, and Michael Kolbe:
Protein refolding is required for assembly of the Type three secretion needle
Nature Structural & Molecular Biology, 13 June 2010

Michael Kolbe | EurekAlert!
Further information:
http://www.mpiib-berlin.mpg.de

More articles from Life Sciences:

nachricht New application for acoustics helps estimate marine life populations
16.01.2018 | University of California - San Diego

nachricht Unexpected environmental source of methane discovered
16.01.2018 | University of Washington Health Sciences/UW Medicine

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

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...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

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

Novel 3-D printing technique yields high-performance composites

16.01.2018 | Materials Sciences

New application for acoustics helps estimate marine life populations

16.01.2018 | Life Sciences

Fast-tracking T cell therapies with immune-mimicking biomaterials

16.01.2018 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>