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Staphylococcus aureus Growth using Human Hemoglobin as an Iron Source
Published on: February 7, 2013
Heme binding properties of Staphylococcus aureus IsdE
Mark Pluym1, Christie L Vermeiren, John Mack
1Department of Chemistry, University of Western Ontario, London, Ontario, Canada N6A 5C1.
Biochemistry
|October 13, 2007
Summary
Staphylococcus aureus uses the IsdE protein to acquire iron via heme binding. This unique histidine-methionine ligation mechanism is crucial for bacterial survival and infection.
Area of Science:
- Microbiology
- Biochemistry
- Structural Biology
Background:
- Staphylococcus aureus causes severe hospital-acquired infections.
- Iron acquisition is vital for S. aureus survival and growth.
- Isd proteins are involved in heme acquisition by S. aureus.
Purpose of the Study:
- Characterize the S. aureus heme-binding protein IsdE.
- Investigate the ligand and redox properties of heme bound by IsdE.
- Determine the structural characteristics of IsdE in heme-bound and heme-free states.
Main Methods:
- Magnetic circular dichroism (MCD) spectroscopy.
- Site-directed mutagenesis.
- Electrospray ionization mass spectrometry (ESI-MS).
Main Results:
- IsdE binds both ferric and ferrous heme, predominantly low-spin ferrous heme.
- Heme iron ligation involves proximal histidine and distal methionine, a unique mechanism for heme transport.
- IsdE binds one heme ligand per molecule with minimal conformational change upon heme binding.
- Heme-free IsdE exhibits distinct conformations under denaturing conditions.
Conclusions:
- IsdE's unique histidine-methionine ligation is critical for heme transport in S. aureus.
- IsdE structure is largely independent of heme, with reversible unfolding observed.
- Understanding IsdE function provides insights into S. aureus iron acquisition strategies.
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