Backbone 1H, 13C and 15N resonance assignments of the 39 kDa staphylococcal hemoglobin receptor IsdH

During infections Stahpylococcus aureus preferentially uses heme as an iron source, which it captures from human hemoglobin using the Iron regulated surface determinant (Isd) system. On the cell surface two related staphylococcal surface receptors called IsdH and IsdB bind to hemoglobin and extract its heme. Both receptors contain multiple NEAr iron Transporter (NEAT) domains that either bind to hemoglobin, or to heme. All previous structural studies have investigated individual NEAT domains and have not explored how the domains might interact with one another to synergistically extract heme from hemoglobin. Here, we report the near complete 1H, 13C and 15N backbone resonance assignments of a bi-domain unit from IsdH that contains the N2 and N3 NEAT domains, which bind to hemoglobin and heme, respectively (IsdHN2N3, residues 326–660, 39 kDa). The assigned backbone resonances lay the foundation for future NMR studies that will explore the molecular basis of IsdH function.