Bacterial heme uptake system (HAS)

The bacterial heme uptake system is a complex protein network used by pathogenic bacteria to acquire essential iron from host heme-containing molecules like hemoglobin and hemopexin (NIH, 2020). In the iron-restricted environment of a host, bacteria rely on this system to overcome 'nutritional immunity' and sustain growth and virulence (Frontiers in Microbiology, 2022). The system typically comprises secreted hemophores that scavenge heme, TonB-dependent outer membrane receptors for internalization, and ABC transporters that deliver heme to the cytoplasm for degradation by heme oxygenases (NIH, 2020; OUP, 2024). Because these pathways are critical for the survival of many multi-drug resistant pathogens, they have become attractive targets for novel antimicrobial development (NIH, 2020). Therapeutic approaches include the use of 'Trojan horse' heme analogs, such as gallium-protoporphyrin IX, which exploit the uptake machinery to deliver toxic metal ions into the bacterial cell (Future Med Chem, 2014). Additionally, vaccines and monoclonal antibodies are being developed to target surface-exposed components of the system, such as the Isd proteins in Staphylococcus aureus, to block nutrient acquisition and attenuate infection (NIH, 2020; Frontiers in Immunology, 2021).

Other names

Heme acquisition systemHeme transport systemHeme iron uptake pathwayHemophore-mediated uptake systemHmu systemPhu systemIsd system

Competitive inhibition of heme binding, Trojan horse delivery of toxic metal analogs, and neutralization of surface receptors to prevent iron acquisition (NIH, 2020; Future Med Chem, 2014).