Biology of Intracelluar Bacteria
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Institut Pasteur, CNRS UMR 3525
28, Rue du Dr Roux,
75014 Paris
France
Scientific Interest
Horizontal gene transfer (HGT) plays a major role in the diversification and the evolution of bacterial species and is a central question in the study of the evolution of bacteria. It allows to understand the emergence of specific clones and the rapid adaptation to changing environments like those encountered during the interaction with a host. Mobile genetic elements (MGE) belonging to different families (plasmids, integrative conjugative elements and pathogenicity islands (PAI) are important players in the emergence of pathogens. We are studying bacteria belonging to the genus Legionella. These are environmental bacteria replicating in aquatic protozoa, but in particular L. pneumophila and L. longbaechae are also human pathogens that cause a severe pneumonia that can be fatal in 5% to 20% of the case; These bacteria have evolved their pathogenicity features during co-evolution with protozoan cells and we have shown by sequence, evolutionary and phylogenetics analyses that many of their virulence genes have been acquired by HGT from their protozoan hosts. We aim to understand the mechanism of gene transfer between domains of life, and hypothesize that MGE and phage like elements are implicated. Furthermore, several of the acquired genes are secreted factors that modulate the epigenetics landscape of the host cell. Thus, a second axe of our research is to understand the mechanism and identify which epigenetic changes are induced by L. pneumophila during infection.
Horizontal gene transfer (HGT) plays a major role in the diversification and the evolution of bacterial species and is a central question in the study of the evolution of bacteria. It allows to understand the emergence of specific clones and the rapid adaptation to changing environments like those encountered during the interaction with a host. Mobile genetic elements (MGE) belonging to different families (plasmids, integrative conjugative elements and pathogenicity islands (PAI) are important players in the emergence of pathogens. We are studying bacteria belonging to the genus Legionella. These are environmental bacteria replicating in aquatic protozoa, but in particular L. pneumophila and L. longbaechae are also human pathogens that cause a severe pneumonia that can be fatal in 5% to 20% of the case; These bacteria have evolved their pathogenicity features during co-evolution with protozoan cells and we have shown by sequence, evolutionary and phylogenetics analyses that many of their virulence genes have been acquired by HGT from their protozoan hosts. We aim to understand the mechanism of gene transfer between domains of life, and hypothesize that MGE and phage like elements are implicated. Furthermore, several of the acquired genes are secreted factors that modulate the epigenetics landscape of the host cell. Thus, a second axe of our research is to understand the mechanism and identify which epigenetic changes are induced by L. pneumophila during infection.
Thematic