Structural highlights
Function[ISDH_STAAS] Binds human plasma haptoglobin-hemoglobin complexes, haptoglobin and hemoglobin. Binds haptoglobin-hemoglobin complexes with significantly higher affinity than haptoglobin alone (Probable). Publication Abstract from PubMedDuring infections the pathogen Staphylococcus aureus procures the essential nutrient iron from its host using iron-regulated surface determinant (Isd) proteins, which scavenge heme bound iron from host hemoproteins. Four Isd proteins are displayed in the cell wall, where they function as receptors for host proteins and heme. Each of the receptors contains one or more copies of a recently discovered domain called NEAT (NEAr Transporter) that has been shown to mediate protein binding. Here we report the three-dimensional solution structure of the NEAT domain from the IsdH/HarA protein, which is the hemoglobin receptor in the Isd system. This is the first structure of a NEAT domain and reveals that they adopt a beta sandwich fold that consists of two five-stranded antiparallel beta sheets. Although unrelated at the primary sequence level, our results indicate that NEAT domains belong to the immunoglobulin superfamily. Binding studies indicate that two IsdH/HarA NEAT domains bind a single molecule of methemoglobin, while the distantly related NEAT domain from the S. aureus IsdC protein binds only heme. A comparison of their primary sequences in light of the new structure is used to predict the hemoglobin and heme binding surfaces on NEAT domains. Solution structure of the NEAT (NEAr Transporter) domain from IsdH/HarA: the human hemoglobin receptor in Staphylococcus aureus.,Pilpa RM, Fadeev EA, Villareal VA, Wong ML, Phillips M, Clubb RT J Mol Biol. 2006 Jul 7;360(2):435-47. Epub 2006 May 22. PMID:16762363[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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