2q8p
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(New page: 200px<br /><applet load="2q8p" size="350" color="white" frame="true" align="right" spinBox="true" caption="2q8p, resolution 1.95Å" /> '''Crystal Structure of...)
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Revision as of 10:58, 23 January 2008
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Crystal Structure of selenomethionine labelled S. aureus IsdE complexed with heme
Overview
Staphylococcus aureus is a Gram-positive bacterial pathogen and a leading, cause of hospital acquired infections. Because the free iron concentration, in the human body is too low to support growth, S. aureus must acquire, iron from host sources. Heme iron is the most prevalent iron reservoir in, the human body and a predominant source of iron for S. aureus. The, iron-regulated surface determinant (Isd) system removes heme from host, heme proteins and transfers it to IsdE, the cognate substrate-binding, lipoprotein of an ATP-binding cassette transporter, for import and, subsequent degradation. Herein, we report the crystal structure of the, soluble portion of the IsdE lipoprotein in complex with heme. The, structure reveals a bi-lobed topology formed by an N- and C-terminal, domain bridged by a single alpha-helix. The structure places IsdE as a, member of the helical backbone metal receptor superfamily. A, six-coordinate heme molecule is bound in the groove established at the, domain interface, and the heme iron is coordinated in a novel fashion for, heme transporters by Met(78) and His(229). Both heme propionate groups are, secured by H-bonds to IsdE main chain and side chain groups. Of these, residues, His(229) is essential for IsdE-mediated heme uptake by S. aureus, when growth on heme as a sole iron source is measured. Multiple sequence, alignments of homologues from several other Gram-positive bacteria, including the human pathogens pyogenes, Bacillus anthracis, and Listeria, monocytogenes, suggest that these other systems function equivalently to, S. aureus IsdE with respect to heme binding and transport.
About this Structure
2Q8P is a Single protein structure of sequence from Staphylococcus aureus with as ligand. Full crystallographic information is available from OCA.
Reference
Heme Coordination by Staphylococcus aureus IsdE., Grigg JC, Vermeiren CL, Heinrichs DE, Murphy ME, J Biol Chem. 2007 Sep 28;282(39):28815-22. Epub 2007 Jul 31. PMID:17666394
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