Featured Research

from universities, journals, and other organizations

3-D molecular syringes: Scientists solve structure of infection tool used by Yersinia bacterium

Date:
July 31, 2013
Source:
Helmholtz Centre for Infection Research
Summary:
Abdominal pain, fever, diarrhea -- these symptoms could point to an infection with the bacterium Yersinia. Its pathogenic potential is based on a syringe-like injection apparatus called injectisome. Scientists have now unraveled this molecular syringe's spatial conformation. The researchers demonstrated that the length of Yersinia's injectisome's basal body, which crosses the bacterial cell wall, is adjustable -- very likely an adaptation to physical stress.

Electron microscope image of a bacterial cell: injection apparatuses (shown in red) stick out from the cell and extend across the cell wall (shown here in yellow and blue).
Credit: ฉ Universitไt Basel/Kudryashev

Abdominal pain, fever, diarrhea -- these symptoms could point to an infection with the bacterium Yersinia. The bacterium's pathogenic potential is based on a syringe-like injection apparatus called injectisome. For the first time, an international team of researchers including scientists at the Helmholtz Centre for Infection Research (HZI) in Braunschweig, Germany, has unraveled this molecular syringe's spatial conformation. The researchers were able to demonstrate that the length of Yersinia's injectisome's basal body, which crosses the bacterial cell wall, is adjustable -- very likely an adaptation to physical stress.

The rod-shaped bacterium Yersinia enterocolitica, which is transmitted through contaminated food, causes gastrointestinal diseases. In Germany alone, several thousand cases are reported annually. Yersinia uses a rather sophisticated tool -- its injection apparatus -- to infect humans. Not only does the apparatus look like a syringe, it actually serves a similar purpose. A molecular "needle," which sticks out from the bacterium's surface, extends across the bacterial membranes to the host cell. It is through this needle that the bacterium "injects" substances that facilitate infection of the host. Now, for the first time, an interdisciplinary team of HZI scientists together with their colleagues at the Biozentrum of the University of Basel and at the Ecole Polytechnique F้d้rale de Lausanne in Switzerland, has presented the structure of Yersinia enterocolitica's injectisome in high-resolution and 3D. They published their results in the digital scientific magazine eLife.

Their innovative approach has yielded surprising results. Previous studies had been concerned with isolating the molecular syringe from the bacterium and studying it under the electron microscope. "We, however, actually studied the injectisome in situ, in other words, on the bacterial surface, right where it normally occurs," explains Prof. Henning Stahlberg, University of Basel. To this end, the researchers cooled the bacteria to minus 193 degrees Celsius and used cryo-electron microscopy to take pictures of the syringe from various angles. They then computed a spatial structure from a set of two-dimensional images -- a highly effective method for examining large molecular complexes. The syringe, which consists of some 30 different proteins, definitely falls into that category.

When comparing over 2000 single syringes from over 300 bacteria, the researchers made a surprising discovery: "There is a range of different lengths of each injection apparatus' base -- in some cases, it's on the order of ten nanometers, or ten millionth of a millimeter. It can be stretched or compressed -- just like a spring," explains Dr. Stefan Schmelz of the HZI, one of the study's first authors. As much as we consider such dimensions to be miniscule -- to a bacterium, which itself is but a hundred times that size, they are substantial. "Bacteria are exposed to considerable forces, be it during contact with other cells or upon changes in environmental salinity," explains Prof. Dirk Heinz, the HZI's scientific director and former head of the HZI Department of Molecular Structural Biology. "If the injectisomes were rigidly constructed, bacteria would most likely be unable to resist these forces. Their cell walls would simply rupture."

Insights into the structure of Yersinia's attack tool offer clues as to ways in which the molecular syringe may be therapeutically inhibited. Without this apparatus, the bacteria are practically harmless. "Also other pathogenic bacteria make use of this principle during infection, for example Salmonella that cause food poisoning," confirms Dr. Mikhail Kudryashev, another of the study's primary authors and a researcher at the University of Basel. The team was already able to document this same flexibility in Shigella, the causative agent behind bacillary dysentery. The "molecular building kit," as Schmelz calls it, is highly similar, suggesting that insights from this current study can potentially also be applied to other pathogenic bacteria.


Story Source:

The above story is based on materials provided by Helmholtz Centre for Infection Research. Note: Materials may be edited for content and length.


Journal Reference:

  1. M. Kudryashev, M. Stenta, S. Schmelz, M. Amstutz, U. Wiesand, D. Castano-Diez, M. T. Degiacomi, S. Munnich, C. K. Bleck, J. Kowal, A. Diepold, D. W. Heinz, M. Dal Peraro, G. R. Cornelis, H. Stahlberg. In situ structural analysis of the Yersinia enterocolitica injectisome. eLife, 2013; 2 (0): e00792 DOI: 10.7554/elife.00792

Cite This Page:

Helmholtz Centre for Infection Research. "3-D molecular syringes: Scientists solve structure of infection tool used by Yersinia bacterium." ScienceDaily. ScienceDaily, 31 July 2013. <www.sciencedaily.com/releases/2013/07/130731122821.htm>.
Helmholtz Centre for Infection Research. (2013, July 31). 3-D molecular syringes: Scientists solve structure of infection tool used by Yersinia bacterium. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2013/07/130731122821.htm
Helmholtz Centre for Infection Research. "3-D molecular syringes: Scientists solve structure of infection tool used by Yersinia bacterium." ScienceDaily. www.sciencedaily.com/releases/2013/07/130731122821.htm (accessed October 20, 2014).

Share This



More Plants & Animals News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

White Lion Cubs Born in Belgrade Zoo

White Lion Cubs Born in Belgrade Zoo

AFP (Oct. 20, 2014) — Two white lion cubs, an extremely rare subspecies of the African lion, were recently born at Belgrade Zoo. They are being bottle fed by zoo keepers after they were rejected by their mother after birth. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) — He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
Goliath Spider Will Give You Nightmares

Goliath Spider Will Give You Nightmares

Buzz60 (Oct. 20, 2014) — An entomologist stumbled upon a South American Goliath Birdeater. With a name like that, you know it's a terrifying creepy crawler. Sean Dowling (@SeanDowlingTV) has the details. Video provided by Buzz60
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) — Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins