Modeling of the structure of the Haemophilus influenzae heme‐binding protein suggests a mode of heme interaction

The structure and function of the periplasmic heme‐binding protein HbpA of Haemophilus influenzae were investigated. This protein is involved in the import of heme into the bacteria through the inner membrane, and thus is a key element of the organism's ability to survive in blood. A high degree of sequence similarity between HbpA and the dipeptide‐binding protein of Escherichia coli is suggested to be the result of a functional relationship. An HbpA model built using the dipeptide‐binding protein suggests a mode of heme binding that is distinct from those known in proteins of the human host. These results provide a starting point for rational drug design.