The PRE-Derived NMR Model of the 38.8-kDa Tri-Domain IsdH Protein from Staphylococcus aureus Suggests That It Adaptively Recognizes Human Hemoglobin

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dc.citation.firstpage1107
dc.citation.issueNumber6
dc.citation.journalTitleJournal of Molecular Biology
dc.citation.lastpage1129
dc.citation.volumeNumber428
dc.contributor.authorSjodt, Megan
dc.contributor.authorMacdonald, Ramsay
dc.contributor.authorSpirig, Thomas
dc.contributor.authorChan, Albert H.
dc.contributor.authorDickson, Claire F.
dc.contributor.authorFabian, Marian
dc.contributor.authorOlson, John S.
dc.contributor.authorGell, David A.
dc.contributor.authorClubb, Robert T.
dc.date.accessioned2017-05-03T16:12:50Z
dc.date.available2017-05-03T16:12:50Z
dc.date.issued2016
dc.description.abstractStaphylococcus aureus is a medically important bacterial pathogen that, during infections, acquires iron from human hemoglobin (Hb). It uses two closely related iron-regulated surface determinant (Isd) proteins to capture and extract the oxidized form of heme (hemin) from Hb, IsdH and IsdB. Both receptors rapidly extract hemin using a conserved tri-domain unit consisting of two NEAT (near iron transporter) domains connected by a helical linker domain. To gain insight into the mechanism of extraction, we used NMR to investigate the structure and dynamics of the 38.8-kDa tri-domain IsdH protein (IsdHN2N3, A326–D660 with a Y642A mutation that prevents hemin binding). The structure was modeled using long-range paramagnetic relaxation enhancement (PRE) distance restraints, dihedral angle, small-angle X-ray scattering, residual dipolar coupling and inter-domain NOE nuclear Overhauser effect data. The receptor adopts an extended conformation wherein the linker and N3 domains pack against each other via a hydrophobic interface. In contrast, the N2 domain contacts the linker domain via a hydrophilic interface and, based on NMR relaxation data, undergoes inter-domain motions enabling it to reorient with respect to the body of the protein. Ensemble calculations were used to estimate the range of N2 domain positions compatible with the PRE data. A comparison of the Hb-free and Hb-bound forms reveals that Hb binding alters the positioning of the N2 domain. We propose that binding occurs through a combination of conformational selection and induced-fit mechanisms that may promote hemin release from Hb by altering the position of its F helix.
dc.identifier.citationSjodt, Megan, Macdonald, Ramsay, Spirig, Thomas, et al.. "The PRE-Derived NMR Model of the 38.8-kDa Tri-Domain IsdH Protein from Staphylococcus aureus Suggests That It Adaptively Recognizes Human Hemoglobin." <i>Journal of Molecular Biology,</i> 428, no. 6 (2016) Elsevier: 1107-1129. https://doi.org/10.1016/j.jmb.2015.02.008.
dc.identifier.doihttps://doi.org/10.1016/j.jmb.2015.02.008
dc.identifier.urihttps://hdl.handle.net/1911/94129
dc.language.isoeng
dc.publisherElsevier
dc.rightsThis is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier.
dc.subject.keywordparamagnetic relaxation enhancement
dc.subject.keywordlarge protein NMR
dc.subject.keywordiron-regulated surface determinant system
dc.subject.keywordhemoglobin receptor
dc.subject.keywordnuclear magnetic resonance spectroscopy
dc.titleThe PRE-Derived NMR Model of the 38.8-kDa Tri-Domain IsdH Protein from Staphylococcus aureus Suggests That It Adaptively Recognizes Human Hemoglobin
dc.typeJournal article
dc.type.dcmiTexten_US
dc.type.publicationpost-print
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