Heme is an indispensable cofactor for almost all aerobic life, including the human host and many bacterial pathogens. During
infection,
heme and hemoproteins are the largest source of bioavailable
iron, and pathogens have evolved various
heme acquisition pathways to satisfy their need for
iron and
heme. Many of these pathways are regulated transcriptionally by intracellular
iron levels, however, host
heme availability and intracellular
heme levels have also been found to regulate
heme uptake in some species. Knowledge of these pathways has helped to uncover not only how these bacteria incorporate host
heme into their metabolism but also provided insight into the importance of host
heme as a nutrient source during
infection. Within this review is covered multiple aspects of the role of
heme at the host pathogen interface, including the various routes of
heme biosynthesis, how
heme is sequestered by the host, and how
heme is scavenged by bacterial pathogens. Also discussed is how
heme and hemoproteins alter the behavior of the host immune system and bacterial pathogens. Finally, some unanswered questions about the regulation of
heme uptake and how host
heme is integrated into bacterial metabolism are highlighted.