Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Genotoxic bacteria in the digestive tract

14.08.2006
Escherichia coli is a commensal bacterium, which lives peacefully in our digestive tract. However, certain strains are pathogenic and are frequently incriminated in a broad spectrum of infections, affecting both farmed animals and humans (diarrhoea, urinary tract infections, food poisoning, septicaemia, neonatal meningitis, etc.).

In this respect, E. coli is a model bacterium to study the continuum between commensal and pathogenic bacteria. Researchers at INRA in Toulouse, in collaboration with German universities in Würzburg and Göttingen and the Institut Pasteur in Paris, have shown for the first time that both commensal and pathogenic E. coli produce a substance which is toxic to the DNA in eukaryotic cells. The bacteria producing this toxin thus induce DNA breaks in host cells and disturb the cell cycle. This slowdown of eukaryotic cell proliferation may enhance bacterial colonization of the intestine. On the other hand, if these breaks are not repaired, they could give rise to a high level of mutations, which are the principal factors triggering cancer in man. The details of this work have been published in Science, August 11th 2006.

Colibactin, a new toxin which affects the host cell cycle

Certain strains of E. coli produce a toxin, which induces a toxic effect in host cells, characterised by gradual cell enlargement following the arrest of cell proliferation. INRA researchers in Toulouse, in collaboration with teams at the German universities of Würzburg and Göttingen and the Institut Pasteur in Paris, have demonstrated that these bacterial strains possess a "genomic island" in their genome, which contains all genes allowing the biosynthesis of a new toxin, which they have called "Colibactin". The researchers have shown that the bacteria producing this toxin induce serious lesions to the DNA of host cells, causing a blockade of the cell cycle of infected cells. Colibactin belongs to a new family of bacterial toxins, which are able to act on the cell cycle of eukaryotic cells. The INRA researchers have proposed to call this family the "cyclomodulins".

Colibactin is a non-protein toxin. The genes carried by the genomic island code for several enzymes belonging to the family of "polyketide synthetases" (PKS) and "nonribosomal polypeptide synthetases" (NRPS). Compounds arising from these biosynthetic pathways constitute a large family of natural products with a very broad range of biological activities and pharmacological properties. This family comprises numerous molecules which are of importance both agronomically (anti-parasite substances, such as avermectin) and medically (e.g. immunosuppressants, cholesterol-lowering agents, anticancer compounds and antibiotics (cyclosporine, lovastatin, bleomycin, erythromycin, etc.). This is the first time that an enzyme system of this type, producing a molecule active on eukaryote cells, has been characterised in E. coli, a bacterial species where genetic engineering is well mastered. This discovery provides a biotechnological key to producing new compounds of interest, and has been the subject of a patent application. It opens the way to novel therapeutic approaches as well as preventive opportunities.

Infectious diseases, cancer and anti-proliferative effects: is there a role for bacteria producing cyclomodulins?

The work reported in Science also raises an important question for public health. DNA double strand breaks are dangerous lesions affecting eukaryotic cells; if these are not repaired, they give rise to a high level of mutations, which are the principal triggers of cancer in man. Colibactin is produced by both commensal E. coli in the intestinal flora and pathogenic strains which are responsible for septicaemia, urinary tract infections and meningitis. The presence of these bacteria in the commensal flora may therefore constitute a predisposing factor for the development of certain cancers. Thus bacterial flora may participate in the development, differentiation and homeostasis of mucosa and hence the development of certain types of cancer, or protection against them.

Céline Goupil | alfa
Further information:
http://www.inra.fr
http://www.international.inra.fr/press/genotoxic_bacteria_in_the_digestive_tract

More articles from Life Sciences:

nachricht Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care

nachricht Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>