Featured Research

from universities, journals, and other organizations

When Intestinal Bacteria Go Surfing: Molecular Signal Pathway In Diarrhea Illnesses Identified

Date:
March 26, 2009
Source:
Helmholtz Association of German Research Centres
Summary:
The bacterium Escherichia coli is part of the healthy human intestinal flora. However, E. coli also has pathogenic relatives that trigger diarrhea illnesses: enterohemorrhagic E.coli bacteria. During the course of an infection they infest the intestinal mucosa, causing injury in the process, in contrast to benign bacteria.

An EHEC-bacterium sitting on a pedestal on an intestional cell.
Credit: Image courtesy of Helmholtz Association of German Research Centres

The bacterium Escherichia coli is part of the healthy human intestinal flora. However, E. coli also has pathogenic relatives that trigger diarrhea illnesses: enterohemorrhagic E.coli bacteria. During the course of an infection they infest the intestinal mucosa, causing injury in the process, in contrast to benign bacteria.

The EHECs adhere to the surface of the mucosal cells and alter them internally: a part of the cellular supportive skeleton - the actin skeleton - is rearranged in such a manner that the cell surface beneath the bacteria forms plinth-like growths, so-called pedestals. The bacteria are securely anchored to this pedestal; the pedestals, in contrast, are mobile. This enables the bacteria, seated upon them, to surf over the cell surface and reproduce upon it, without being flushed from the intestine. But how do the bacteria bring the host cells to convert the actin skeleton? Researchers at the Helmholtz Centre for Infection Research (HZI) have now identified the signal pathway that leads to the formation of this pedestal.

"Prerequisite for this signal pathway is a special secretion system - a sort of molecular syringe, through which the bacteria insert entire proteins in the host cell," explains Theresia Stradal, head of the Signal Transduction and Motility research group at HZI. Two factors, Tir and EspFU, are brought into the host cell from the bacterium for pedestal formation. Following this, the host cell presents Tir on its surface; the bacterium recognises "its" molecule Tir and adheres to the host cell. EspFU then triggers the signal for local actin conversion.

"It has been unclear thus far how the two bacterial effectors Tir and EspFU enter into contact with one another in the host cell," says Theresia Stradal. Her research group has now found the missing link: "The molecule comes from the host cell, is called IRSp53 and gathers on the cell surface, directly beneath the bacteria sitting on it," explains cell biologist Markus Ladwein, who is also involved in the project. IRSp53, then, establishes the connection between Tir and EspFU. It ensures that actin conversion is concentrated locally. Together with the biochemist Dr. Stefanie Weiί, a former post-graduate student with the research group, Markus Ladwein also provided the counter evidence: "Cells in which IRSp53 is lacking are no longer able to form pedestals for the bacteria."

The signal pathway clarified by the Braunschweig researchers – published in the journal Cell Host & Microbe – is a good example of how pathogenic bacteria develop progressively with their host. With the aid of bacterial factors, they therefore manage to simulate signals and set in motion complex processes in the host, which they then abuse for their own purposes.


Story Source:

The above story is based on materials provided by Helmholtz Association of German Research Centres. Note: Materials may be edited for content and length.


Journal Reference:

  1. Stefanie M. Weiss, Markus Ladwein, Dorothea Schmidt, Julia Ehinger, Silvia Lommel, Kai Stδding, Ulrike Beutling, Andrea Disanza, Ronald Frank, Lothar Jδnsch, Giorgio Scita, Florian Gunzer, Klemens Rottner, and Theresia E.B. Stradal. IRSp53 Links the Enterohemorrhagic E. coli Effectors Tir and EspFU for Actin Pedestal Formation. Cell Host & Microbe, 2009; 5 (3): 244-58 DOI: 10.1016/j.chom.2009.02.003

Cite This Page:

Helmholtz Association of German Research Centres. "When Intestinal Bacteria Go Surfing: Molecular Signal Pathway In Diarrhea Illnesses Identified." ScienceDaily. ScienceDaily, 26 March 2009. <www.sciencedaily.com/releases/2009/03/090319102311.htm>.
Helmholtz Association of German Research Centres. (2009, March 26). When Intestinal Bacteria Go Surfing: Molecular Signal Pathway In Diarrhea Illnesses Identified. ScienceDaily. Retrieved August 20, 2014 from www.sciencedaily.com/releases/2009/03/090319102311.htm
Helmholtz Association of German Research Centres. "When Intestinal Bacteria Go Surfing: Molecular Signal Pathway In Diarrhea Illnesses Identified." ScienceDaily. www.sciencedaily.com/releases/2009/03/090319102311.htm (accessed August 20, 2014).

Share This




More Plants & Animals News

Wednesday, August 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Awesome New Camouflage Sheet Was Inspired By Octopus Skin

Newsy (Aug. 19, 2014) — Scientists have developed a new device that mimics the way octopuses blend in with their surroundings to hide from dangerous predators. Video provided by Newsy
Powered by NewsLook.com
Disquieting Times for Malaysia's 'fish Listeners'

Disquieting Times for Malaysia's 'fish Listeners'

AFP (Aug. 19, 2014) — Malaysia's last "fish listeners" -- practitioners of a dying local art of listening underwater to locate their quarry -- try to keep the ancient technique alive in the face of industrial trawling and the depletion of stocks. Duration: 02:29 Video provided by AFP
Powered by NewsLook.com
USDA Cracks Down On Imports From Foreign Puppy Mills

USDA Cracks Down On Imports From Foreign Puppy Mills

Newsy (Aug. 18, 2014) — New USDA measures to regulate dog imports aim to crack down on buying dogs from overseas puppy mills. Video provided by Newsy
Powered by NewsLook.com
Bone Marrow Drug Regrows Hair In Some Alopecia Patients

Bone Marrow Drug Regrows Hair In Some Alopecia Patients

Newsy (Aug. 18, 2014) — Researchers performed an experiment using an FDA-approved drug known as ruxolitinib. They found it to be successful in the majority of patients. Video provided by Newsy
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