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 Rochester scientists discover gene controlling genetic recombination rates
23.04.2018 | University of Rochester

nachricht One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>