Structural Basis for Multimeric Heme Complexation through a Specific Protein-Heme Interaction

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, exa...

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Bibliographic Details
Published in:The Journal of biological chemistry 2008-10, Vol.283 (42), p.28649-28659
Main Authors: Watanabe, Masato, Tanaka, Yoshikazu, Suenaga, Ayuko, Kuroda, Makoto, Yao, Min, Watanabe, Nobuhisa, Arisaka, Fumio, Ohta, Toshiko, Tanaka, Isao, Tsumoto, Kouhei
Format: Article
Language:English
Subjects:
Protein Structure and Folding
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Summary: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.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M803383200