Featured Research

from universities, journals, and other organizations

Researchers discover a new type of toxic protein

Date:
November 12, 2012
Source:
Christian-Albrechts-Universitaet zu Kiel
Summary:
Researchers have discovered a toxic protein of pathogenic acanthamoebae and have been able to elucidate its three-dimensional structure. They found that this protein molecule looks different from all the structures formerly discovered. The acanthamoeba secretes a cell toxin (Acanthaporin); when roused from its inactive state this toxin infiltrates human nerve cells or bacteria and embeds itself in the plasma membrane, forming a kind of circular channel (pore).

The model shows how the activated monomer acanthaporin (golden three-dimensional structure) transforms into a hexamer inside the membrane of the cell under attack. This leads to the emission of cellular components and finally results in the cell’s death. The different colourings on the protein’s surface indicate the varying charge distribution within the membrane pore (blue: positive charges; red: negative charges; white: uncharged; red ring: pore opening).
Credit: Copyright: Kiel University; Picture: Matthias Michalek

Researchers at Kiel University have discovered a toxic protein of pathogenic acanthamoebae and have been able to elucidate its three-dimensional structure. They found that this protein molecule looks different from all the structures formerly discovered. The acanthamoeba secretes a cell toxin (Acanthaporin); when roused from its inactive state this toxin infiltrates human nerve cells or bacteria and embeds itself in the plasma membrane, forming a kind of circular channel (pore).

This discovery is published in the current issue of Nature Chemical Biology.

Acanthamoebae are free-living unicellular organisms, which occur in soil and water where they feed on other microorganisms. For humans, certain amoebas of this genus are dangerous because they can cause diseases. The parasite can infest the nervous system and may cause death. Compared to commonly known tropical diseases such as malaria or amoebic dysentery, which are also caused by parasitic unicellular organisms, such a fatal outcome is relatively rare and affects primarily patients with a weak immune system. In the medical field, acanthamoeba is better known as an actuator for painful inflammation of the cornea, known as amoebic keratitis. People who wear contact lenses mainly suffer from this disease that can lead to complete blindness. Furthermore, the parasite often carries other bacterial pathogens within its cellular body like the one causing Legionnaire's disease. For this reason, acanthamoebae are dubbed "Trojan horses."

The current scientific findings are the result of close collaboration between two teams of scientists supervised by Professor Matthias Leippe (Zoophysiology, Institute of Zoology at Kiel University) und Professor Joachim Grötzinger (Structural Biology, Institute of Biochemistry at Kiel University). The findings were to a major extent collected by Matthias Michalek, then a mutual doctorate candidate studying under both Leippe and Grötzinger. As the project started to grow, the scientists were joined by colleagues from Kiel University and from the Research Center Borstel. The latter has been partner to Kiel University in the cluster "Inflammation at Interfaces" for some years. Furthermore, international experts were asked to join the research.

"For scientists like us, who work on the fundamentals, it is very satisfying if we are able not only to discover such an interesting protein, but in the end are able to see exactly what it looks like. In that way we can learn more about its mode of action," said the initiator of the study, Matthias Leippe, adding: "It is even more satisfying if it turns out to be a completely new structure. A discovery such as this hardly ever happens nowadays." He continued to explain: "The principle of distributing soluble proteins which incorporate themselves into cell membranes and form pores is however not new. We find the same mechanisms with bacterial pathogens or in our own immune system. This is why we refer to these proteins as 'ancient weapons' that take effect very fast and very effectively. In nature, these mechanisms have proven to be successful for attack and defence."

The scientists hope that thanks to their findings, it will be easier to understand the mysterious circumstances which cause tissue damage and disease caused by acanthamoeba.


Story Source:

The above story is based on materials provided by Christian-Albrechts-Universitaet zu Kiel. Note: Materials may be edited for content and length.


Journal Reference:

  1. Matthias Michalek, Frank D Sönnichsen, Rainer Wechselberger, Andrew J Dingley, Chien-Wen Hung, Annika Kopp, Hans Wienk, Maren Simanski, Rosa Herbst, Inken Lorenzen, Francine Marciano-Cabral, Christoph Gelhaus, Thomas Gutsmann, Andreas Tholey, Joachim Grötzinger, Matthias Leippe. Structure and function of a unique pore-forming protein from a pathogenic acanthamoeba. Nature Chemical Biology, 2012; DOI: 10.1038/NChemBio.1116

Cite This Page:

Christian-Albrechts-Universitaet zu Kiel. "Researchers discover a new type of toxic protein." ScienceDaily. ScienceDaily, 12 November 2012. <www.sciencedaily.com/releases/2012/11/121112090422.htm>.
Christian-Albrechts-Universitaet zu Kiel. (2012, November 12). Researchers discover a new type of toxic protein. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2012/11/121112090422.htm
Christian-Albrechts-Universitaet zu Kiel. "Researchers discover a new type of toxic protein." ScienceDaily. www.sciencedaily.com/releases/2012/11/121112090422.htm (accessed September 19, 2014).

Share This



More Plants & Animals News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

AP (Sep. 18, 2014) — Grand the elephant has successfully undergone surgery to remove a portion of infected tusk at Tbilisi Zoo in Georgia. British veterinary surgeons used an electric drill to extract the infected piece. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Chimp Violence Study Renews Debate On Why They Kill

Chimp Violence Study Renews Debate On Why They Kill

Newsy (Sep. 17, 2014) — The study weighs in on a debate over whether chimps are naturally violent or become that way due to human interference in the environment. Video provided by Newsy
Powered by NewsLook.com
Some Tobacco Farmers Thrive Amid Challenges

Some Tobacco Farmers Thrive Amid Challenges

AP (Sep. 16, 2014) — The South's tobacco country is surviving, and even thriving in some cases, as demand overseas keeps growers in the fields of one of America's oldest cash crops. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

AFP (Sep. 16, 2014) — Scientists say a female colossal squid weighing an estimated 350 kilograms (770 lbs) and thought to be only the second intact specimen ever found was carrying eggs when discovered in the Antarctic. Duration: 00:47 Video provided by AFP
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:
from the past week

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