Non-Heme-Binding Domains and Segments of the Staphylococcus aureus IsdB Protein Critically Contribute to the Kinetics and Equilibrium of Heme Acquisition from Methemoglobin
Figure 9
A schematic model depicting the distinct functions of individual domains of IsdB for the kinetics and equilibrium of the metHb/IsdB heme transfer reaction.
In this model, NS-N1 specifically enhances direct heme assimilation from α and β subunits of metHb by N2; MD enhances the affinity of N2 for heme and favorably drives the equilibrium of the heme transfer reaction; and CS functions as a spacer to place IsdB at an appropriate position in the cell wall envelope of S. aureus for heme relay by the Isd heme acquisition system.