Iron-regulated surface determinants (Isd) of Staphylococcus aureus: stealing iron from heme

Cell-wall sorted proteins of the Staphylococcus aureus iron-regulated surface determinant system bind human hemoproteins, remove the heme molecule, and transport heme through the cell wall and plasma membrane for accumulation in the bacterial cytoplasm. Once inside the cell, the porphyrin ring of heme is degraded by heme degrading monooxygenases, leading to the formation of free iron for use by the bacterium as a nutrient source.