Seminarios

"Helicobacter pylori, the black sheep amongst naturally competent bacterial species" Dr. J. Pablo Radicella

Resumen:

Horizontal gene transfer (HGT) is a major contributor to the spreading of new genetic variants within a bacterial population and thus to its genetic diversity. HGT is therefore critical for the capacity of microorganisms to adapt to environmental changes or to colonise new niches. In pathogens HGT also plays a major role in the spreading of antibacterial resistance genes. Antibiotic resistance is a huge concern in the treatment of bacterial infections and represents an alarming risk to human health in the coming years.

The human gastric pathogen Helicobacter pylori is until now the only bacterium recognised as a class 1 carcinogen and is part of the recent WHO list of antibiotic-resistant “priority pathogens” that pose the greatest threat to human health. H. pylori colonises the stomach of half of the human population worldwide causing chronic gastritis that can evolve into ulcers or cancer that are responsible for 800,000 deaths per year. H. pylori genome presents high mutation rates leading to an amazing genetic diversity most likely contributing to the capacity of H. pylori to persistently colonise large and heterogeneous human populations. In H. pylori, natural transformation, i.e acquisition of exogenous DNA by a cell, is the main HGT mechanism that, together with very efficient recombination systems, results in the rapid spreading of the new alleles. This includes dissemination of antibiotic resistance markers which, in H. pylori, are restricted to chromosomal mutations.

Given that H. pylori is the sole stable coloniser of the stomach and that its genetic variability is not restricted to cases of multiple H. pylori infections, the origin of this spectacular genomic variability has been a fascinating question since its discovery. We will present here our latest results aiming at understanding the mechanisms underlying the efficient transfer of genetic information of this pathogen, which is considered the “black sheep” among naturally transformable bacteria.

Localización : Aula Cardini
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Dr. J. Pablo Radicella
Institut de Biologie François Jacob
CEA, Fontenay aux Roses
Francia

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