IsdB-dependent Hemoglobin Binding Is Required for Acquisition of Heme by Staphylococcus aureus

• Published in: The Journal of infectious diseases Vol. 209; no. 11; pp. 1764 - 1772
• Main Authors: Pishchany, Gleb, Sheldon, Jessica R., Dickson, Claire F., Alam, Md Tauqeer, Read, Timothy D., Gell, David A., Heinrichs, David E., Skaar, Eric P.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01-06-2014
• Subjects: Bacteria; Bacteriology; Biological and medical sciences; Cation Transport Proteins - genetics; Cation Transport Proteins - metabolism; Cell walls; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial - physiology; Genetic mutation; Genetic Variation; Genome, Bacterial; Heme - metabolism; Hemoglobins; Hemoglobins - metabolism; Humans; Infections; Infectious diseases; Iron; Major and Brief Reports; Medical sciences; Mice; Microbiology; Miscellaneous; Protein Binding - physiology; Proteins; Staphylococcus aureus; Staphylococcus aureus - metabolism; Staphylococcus aureus - pathogenicity; Virulence; pathogenesis; iron; infection; iron-regulated surface determinant system; heme; hemoglobin; Infection; Heme; Hemoglobin; Bacteria; Micrococcales; Micrococcaceae; Staphylococcus aureus
• ISSN: 0022-1899; 1537-6613
• DOI: 10.1093/infdis/jit817

Staphylococcus aureus is a Gram-positive pathogen responsible for tremendous morbidity and mortality. As with most bacteria, S. aureus requires iron to cause disease, and it can acquire iron from host hemoglobin. The current model for staphylococcal hemoglobin-iron acquisition proposes that S. aureus binds hemoglobin through the surface-exposed hemoglobin receptor IsdB. IsdB removes heme from bound hemoglobin and transfers this cofactor to other proteins of the Isd system, which import and degrade heme to release iron in the cytoplasm. Here we demonstrate that the individual components of the Isd system are required for growth on low nanomolar concentrations of hemoglobin as a sole source of iron. An in-depth study of hemoglobin binding by IsdB revealed key residues that are required for hemoglobin binding. Further, we show that these residues are necessary for heme extraction from hemoglobin and growth on hemoglobin as a sole iron source. These processes are found to contribute to the pathogenicity of S. aureus in a murine model of infection. Together these results build on the model for Isd-mediated hemoglobin binding and heme-iron acquisition during the pathogenesis of S. aureus infection.