Molecular mechanisms of heme acquisition by Haemophilus influenzae Hgps – HAPTOHEME

Haemophilus influenzae is a bacterium that causes a range of human infections. Since H. influenzae lacks most enzymes of the heme biosynthetic pathway, it has an absolute growth requirement for protoporphyrin IX, the immediate precursor of heme. H. influenzae is one of the few microorganisms able to scavenge heme from the hemoglobin-haptoglobin complex present in human serum. Haptoglobin is a glycoprotein capturing free hemoglobin released in the serum during hemolysis. By allowing the elimination of this potentially toxic products, haptoglobin prevent oxidative damages to the host. At the same time, it participates in the host defense against infection by restricting certain pathogens access to an essential nutrient. The goal of the HAPTOHEME project is to determine the mechanism by which H. influenzae is able to acquire heme from hemoglobin or the haptoglobin-hemoglobin complex.