Members of the Faucher lab have a focused interest on host-pathogen interactions, particularly between intracellular pathogens and mammalian macrophages. How one senses the presence of the other, how the regulatory response is organized, and what tools each of them use are among the top questions that are shaping our research. We use transcriptomic tools extensively to answer these questions, and the data generated from these studies are used to identify new systems involved in host-pathogen interactions.
L. pneumophila microarray.
Our model organism is Legionella pneumophila, a Gram-negative pathogen that can be found in almost any natural or human-made water system. L. pneumophila is able to replicate inside a wide diversity of phagocytic protozoans found in water. It is the causative agent of Legionnaires' disease, an acute form of pneumonia. After inhalation of contaminated water droplets, Legionella infect and replicate inside alveolar macrophages. This phenotype is completely dependent on a Type IVb secretion system that translocates ~200 effectors into the host cells. These effectors modify the normal phagocytic pathway to the benefit of Legionella. Many regulators are known to play a role in the expression of virulence factors, such as two-component systems and small regulatory RNAs (sRNA).
Mechanism of regulation by sRNAs: riboswitch (A), cis-encoded base-pairing sRNA (B), trans-encoded base-pairing sRNA (C), CsrA-CsrB system (D) and the 6S RNA-RNA polymerase system (E). sRNA are colored blue, the mRNA targets are colored in red.