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Structural Basis for Multimeric Heme Complexation through a Specific Protein-Heme Interaction: THE CASE OF THE THIRD NEAT DOMAIN OF IsdH FROM STAPHYLOCOCCUS AUREUS*S⃞

By Masato Watanabe, Yoshikazu Tanaka, Ayuko Suenaga, Makoto Kuroda, Min Yao, Nobuhisa Watanabe, Fumio Arisaka, Toshiko Ohta, Isao Tanaka and Kouhei Tsumoto

Abstract

To elucidate the heme acquisition system in pathogenic bacteria, we investigated the heme-binding properties of the third NEAT domain of IsdH (IsdH-NEAT3), a receptor for heme located on the surfaces of pathogenic bacterial cells, by using x-ray crystallography, isothermal titration calorimetry, examination of absorbance spectra, mutation analysis, size-exclusion chromatography, and analytical ultracentrifugation. We found the following: 1) IsdH-NEAT3 can bind with multiple heme molecules by two modes; 2) heme was bound at the surface of IsdH-NEAT3; 3) candidate residues proposed from the crystal structure were not essential for binding with heme; and 4) IsdH-NEAT3 was associated into a multimeric heme complex by the addition of excess heme. From these observations, we propose a heme-binding mechanism for IsdH-NEAT3 that involves multimerization and discuss the biological importance of this mechanism

Topics: Protein Structure and Folding
Publisher: American Society for Biochemistry and Molecular Biology
OAI identifier: oai:pubmedcentral.nih.gov:2661414
Provided by: PubMed Central
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