Horizontal gene transfer in bacterial pathogens

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Horizontal gene transfer in bacterial pathogens

bacterieHorizontal gene transfer (HGT) is a major actor of genome evolution in bacteria. HGT events are often linked to the emergence of pathogens as well as their adaptation and resistance to therapeutic and prophylactic interventions. Natural transformation is the only mechanism of HGT that is inherent to the species and fully controlled by the bacteria. It occurs when bacteria enter a genetically programmed physiological state called competence. Competence is triggered by conditions or signals that are multiple, elusive and often species-specific. In the competence state, expression of a DNA uptake system confers bacteria the ability to take up free DNA and integrate it in their genome resulting in genetic and phenotypic transformation. Natural transformation is likely common in bacterial pathogens but often undetected because of our limited understanding of the complex signaling and genetics of competence. Indeed, only a limited number of species are naturally transformable under laboratory conditions and the competence of most bacterial species is certainly underestimated.
We study natural transformation in bacterial pathogens with a primary focus on Legionella pneumophila, a pathogen that targets the alveolar macrophage in its human host. We previously found that competence in L. pneumophila is induced by DNA-damaging antibiotics and UV radiation but the underlying mechanisms and genetics are unknown. We also investigate competence in another pathogen known for its propensity to acquire antibiotic resistance genes, Acinetobacter baumannii. In both organisms we intend to investigate the regulation of competence and its function within the context of the infection which may represent a breeding ground, stimulating horizontal transfer of antibiotic resistance genes.
We use a combination of genetics, transcriptomics, molecular biology and microscopy applied to relevant isolates from clinical, veterinary or environmental origins.

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