Heme binding properties of Staphylococcus aureus IsdE.

摘要: Staphylococcus aureus is the source of a large number hospital-acquired infections, which many are serious and can lead to death. Iron critically important survival growth bacterium, complex, multistep mechanisms present fulfill necessary iron requirement. Isd proteins located on wall membrane S. have been proposed function in heme acquisition. We report characterization heme-binding protein IsdE, lipoprotein component membrane-localized ABC transporter that believed key receiving from cell wall-anchored proteins. Magnetic circular dichroism (MCD) data, greatly extend results our initial study IsdE bacterial lysates (Mack, J., Vermeiren, C., Heinrichs, D. E., Stillman, M. J. (2004) Biochem. Biophys. Res. Commun. 320, 781-788), probe ligand redox properties bound heme. The MCD data show when overexpressed E. coli, binds either ferric or ferrous but largest fraction low spin Studies mutants allowed identification ligands fifth sixth position as histidine, proximally, methionine, distally. This histidine-methionine heme-iron ligation unique transport smaller not by allowing for access strong field ligands, such cyanide. Electrospray ionization mass spectral reported first time only one per molecule. These also there little change conformation between heme-bound heme-free species, indicating adopts structure essentially independent clearly reversibly unwinds under denaturing conditions form at least two distinct, conformations.