Study of lipoprotein export to the surface of Bacteroidetes
The phylum Bacteroidetes includes human pathogens and commensals as several members of the human microbiota that play a crucial role in health and disease in particular contributing to the control of gut homeostasis and protection against pathogens. A hallmark of these bacteria is the presence of surface-exposed protein membrane complexes (Sus-like systems).
These systems are unique and have a major role in the biology of Bacteroidetes since they allow the uptake and catabolism of a large variety of nutrients, mainly polysaccharides coming from the host.
During the last years, his work focused at characterizing the function of the Sus-like systems of the dog oral commensal and human pathogen Capnocytophaga canimorsus. He was able to show that these systems play a major role in commensalism and pathogenicity allowing these bacteria to feed on host glycoproteins, to degrade mucin and uptake iron from serotransferrin. Such systems are mainly composed of lipoproteins anchored to the outer membrane and facing the external milieu. This lipoprotein localization is uncommon in most studied Gram-negative bacteria while it is widespread in Bacteroidetes. Little is known on how these complexes assemble and in particular on how lipoproteins are transported to the bacterial surface.
Recently, a signal was identified, the LES, which drives lipoproteins to the surface of C. canimorsus and other Bacteroidetes. This finding suggests the presence of a common new bacterial lipoprotein export pathway that flips lipoproteins across the outer membrane of Bacteroidetes.
The aim of the present research program is to unravel the mechanism of transport of surface exposed lipoproteins using C. canimorsus and Flavobacterium johnsoniae as model organisms.
Overall, Francesco hopes that his research will contribute to a better knowledge of the complex biology of these particular emerging bacteria that are nowadays of extreme interest for the scientific community mainly because of their impact on human health.
Contact : Francesco Renzi