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 Historical rainfall levels are significant in carbon emissions from soil
30.05.2017 | University of Texas at Austin

nachricht 3D printer inks from the woods
30.05.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New Method of Characterizing Graphene

Scientists have developed a new method of characterizing graphene’s properties without applying disruptive electrical contacts, allowing them to investigate both the resistance and quantum capacitance of graphene and other two-dimensional materials. Researchers from the Swiss Nanoscience Institute and the University of Basel’s Department of Physics reported their findings in the journal Physical Review Applied.

Graphene consists of a single layer of carbon atoms. It is transparent, harder than diamond and stronger than steel, yet flexible, and a significantly better...

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

3D printer inks from the woods

30.05.2017 | Life Sciences

How circadian clocks communicate with each other

30.05.2017 | Life Sciences

Graphene and quantum dots put in motion a CMOS-integrated camera that can see the invisible

30.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>