Featured Research

from universities, journals, and other organizations

Bacteria with vuvuzelas: Microbes use a channel protein as a syringe for toxins

Date:
March 20, 2013
Source:
Max-Planck-Gesellschaft
Summary:
The bacterium Photorhabdus luminescens is a constant companion of some roundworms. These worms assault insect larvae, thereby infecting them with the bacteria; the pathogens then attack the cells of their victims with a deadly cocktail of various toxins. Scientists have now discovered that the bacteria use an important toxin complex like a syringe.

Molecular vuvuzela: The central channel of the TcA proteins (light green) is shaped like a vuvuzela horn, the South African musical instrument (dark green: outer shell, black: cell membrane of the host cell).
Credit: Image courtesy of Max-Planck-Gesellschaft

The bacterium Photorhabdus luminescens is a constant companion of some roundworms. These worms assault insect larvae, thereby infecting them with the bacteria; the pathogens then attack the cells of their victims with a deadly cocktail of various toxins. Scientists at the Max Planck Institute of Molecular Physiology in Dortmund working together with colleagues from Freiburg University and Jacobs University Bremen, have discovered that the bacteria use an important toxin complex like a syringe. It makes its way into the host cells via constricted vesicles in the cell membranes, and modifies their structure from within. Part of the toxin complex then forces its way inside the cell through the vesicle membrane by means of a vuvuzela-like protein channel, and kills the cell.

Related Articles


Important toxins of Photorhabdus luminescens are counted among the ABC toxins, which consist of the three protein components TcA, TcB and TcC. The toxin complex first docks at receptor molecules on the membrane of the host cell and is sucked inside the cell in small membrane blisters called vesicles. The TcC components then make their way into the cell fluid and demolish the cell's protein skeleton. What has remained unclear to date, however, was how the protein managed to get through the vesicle membrane.

Now, for the first time, scientists have been able to decode the structure of Photorhabdus luminescens' ABC toxins using cryoelectron microscopy and single particle analysis. This shows that the bacterium's TcA protein consists of five subunits that together form the shape of a bell. "Inside the bell, the subunits form a channel that has one wide and one narrow aperture, so that it looks like the notorious vuvuzela horn used by South African football fans," explains Stefan Raunser of the Max Planck Institute of Molecular Physiology.

As soon as the pH value of the environment rises or falls, for example when the fluid in the vesicles turns acid, the outer shell of the toxin opens, unblocking the central channel. "Now the channel is pushed through the cell membrane like the needle of a syringe," says Raunser. TcB and TcC are drawn into the area between the channel and the shell, where TcC is unpacked and loses its original structure. "It may be that a drop in electrical tension or some specific unpacking proteins such as TcB are necessary for TcC to exit the vesicle and enter the cell, where it can unleash its deadly effects."

The results show that the TcA of roundworm bacteria is similar in shape to the toxins of the plague pathogen and other bacteria. "This may mean that these findings will also reveal the workings of bacteria that induce disease in humans," says Raunser. The findings could also help in the development of pest-resistant crops.

In addition to the ABC toxins, plague pathogens have developed another transport system that also occurs in the pathogens of dysentery and typhus. Known as the type III secretion system, it also looks like a syringe. However, the body of the syringe is embedded in the bacterial membrane, with the needle pointing outwards. The bacteria use these nanosyringes to inject material directly into their host cells.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. Christos Gatsogiannis, Alexander E. Lang, Dominic Meusch, Vanda Pfaumann, Oliver Hofnagel, Roland Benz, Klaus Aktories, Stefan Raunser. A syringe-like injection mechanism in Photorhabdus luminescens toxins. Nature, 2013; DOI: 10.1038/nature11987

Cite This Page:

Max-Planck-Gesellschaft. "Bacteria with vuvuzelas: Microbes use a channel protein as a syringe for toxins." ScienceDaily. ScienceDaily, 20 March 2013. <www.sciencedaily.com/releases/2013/03/130320155127.htm>.
Max-Planck-Gesellschaft. (2013, March 20). Bacteria with vuvuzelas: Microbes use a channel protein as a syringe for toxins. ScienceDaily. Retrieved November 29, 2014 from www.sciencedaily.com/releases/2013/03/130320155127.htm
Max-Planck-Gesellschaft. "Bacteria with vuvuzelas: Microbes use a channel protein as a syringe for toxins." ScienceDaily. www.sciencedaily.com/releases/2013/03/130320155127.htm (accessed November 29, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Saturday, November 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Research on Bats Could Help Develop Drugs Against Ebola

Research on Bats Could Help Develop Drugs Against Ebola

AFP (Nov. 28, 2014) In Africa's only biosafety level 4 laboratory, scientists have been carrying out experiments on bats to understand how virus like Ebola are being transmitted, and how some of them resist to it. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
New Dinosaur Species Found in Museum Collection

New Dinosaur Species Found in Museum Collection

Reuters - Innovations Video Online (Nov. 27, 2014) A British palaeontologist has discovered a new species of dinosaur while studying fossils in a Canadian museum. Pentaceratops aquilonius was related to Triceratops and lived at the end of the Cretaceous Period, around 75 million years ago. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Tryptophan Isn't Making You Sleepy On Thanksgiving

Tryptophan Isn't Making You Sleepy On Thanksgiving

Newsy (Nov. 27, 2014) Tryptophan, a chemical found naturally in turkey meat, gets blamed for sleepiness after Thanksgiving meals. But science points to other culprits. Video provided by Newsy
Powered by NewsLook.com
Classic Hollywood Memorabilia Goes Under the Hammer

Classic Hollywood Memorabilia Goes Under the Hammer

Reuters - Entertainment Video Online (Nov. 26, 2014) The iconic piano from "Casablanca" and the Cowardly Lion suit from "The Wizard of Oz" fetch millions at auction. Sara Hemrajani reports. Video provided by Reuters
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