The bacterial pathogen Staphylococcus aureus uses two closely related receptors located on its surface, IsdH and IsdB, to capture from haemoglobin (Hb) the iron it needs to grow. Both proteins show conserved near iron transporter (NEAT) domains (Pfam:PF05031) that function synergistically. These domains, essential for the arrest of iron, are appropriately positioned by an alpha-helical linker domain (this entry), which does not interact itself with the heme group. In IsdH, this linker domain forms a three-helix bundle structure that is essential for efficient heme capture [1-4].

1: Staphylococcus aureus uses a novel multidomain receptor to break apart human hemoglobin and steal its heme. Spirig T, Malmirchegini GR, Zhang J, Robson SA, Sjodt M, Liu M, Krishna Kumar K, Dickson CF, Gell DA, Lei B, Loo JA, Clubb RT; J Biol Chem. 2013;288:1065-1078. PMID:23132864

2: Structure of the hemoglobin-IsdH complex reveals the molecular basis of iron capture by Staphylococcus aureus. Dickson CF, Kumar KK, Jacques DA, Malmirchegini GR, Spirig T, Mackay JP, Clubb RT, Guss JM, Gell DA; J Biol Chem. 2014;289:6728-6738. PMID:24425866

3: The structure of haemoglobin bound to the haemoglobin receptor IsdH from Staphylococcus aureus shows disruption of the native alpha-globin haem pocket. Dickson CF, Jacques DA, Clubb RT, Guss JM, Gell DA; Acta Crystallogr D Biol Crystallogr. 2015;71:1295-1306. PMID:26057669

4: Structure-function analyses reveal key features in Staphylococcus aureus IsdB-associated unfolding of the heme-binding pocket of human hemoglobin. Bowden CFM, Chan ACK, Li EJW, Arrieta AL, Eltis LD, Murphy MEP; J Biol Chem. 2018;293:177-190. PMID:29109153