Journal of Biomolecular NMR

, 35:53

Heteronuclear multidimensional NMR and homology modelling studies of the C-terminal nucleotide-binding domain of the human mitochondrial ABC transporter ABCB6

Authors

  • Kaori Kurashima-Ito
    • Cellular and Molecular Biology LaboratoryRIKEN
    • Molecular and Cellular Physiology LaboratoryInternational Graduate School of Arts and Sciences, Supramolecular Biology, Yokohama City University
    • CREST/Japan Science and Technology Agency (JST)
  • Teppei Ikeya
    • National Institute of Advanced Industrial Science and Technology (AIST),
  • Hiroshi Senbongi
    • Cellular and Molecular Biology LaboratoryRIKEN
    • Mitochondrial Diseases Group, MRC Dunn Human Nutrition Unit
  • Hidehito Tochio
    • Molecular Biophysics LaboratoryInternational Graduate School of Arts and Sciences, Supramolecular Biology, Yokohama City University
  • Tsutomu Mikawa
    • Cellular and Molecular Biology LaboratoryRIKEN
    • Molecular and Cellular Physiology LaboratoryInternational Graduate School of Arts and Sciences, Supramolecular Biology, Yokohama City University
    • CREST/Japan Science and Technology Agency (JST)
  • Takehiko Shibata
    • Cellular and Molecular Biology LaboratoryRIKEN
    • Molecular and Cellular Physiology LaboratoryInternational Graduate School of Arts and Sciences, Supramolecular Biology, Yokohama City University
    • Shibata Distinguished Senior Scientist LaboratoryRIKEN
    • Cellular and Molecular Biology LaboratoryRIKEN
    • Molecular and Cellular Physiology LaboratoryInternational Graduate School of Arts and Sciences, Supramolecular Biology, Yokohama City University
    • CREST/Japan Science and Technology Agency (JST)
    • Department of ChemistryTokyo Metropolitan University
Article

DOI: 10.1007/s10858-006-9000-6

Cite this article as:
Kurashima-Ito, K., Ikeya, T., Senbongi, H. et al. J Biomol NMR (2006) 35: 53. doi:10.1007/s10858-006-9000-6

Abstract

Human ATP-binding cassette, sub-family B, member 6 (ABCB6) is a mitochondrial ABC transporter, and presumably contributes to iron homeostasis. Aimed at understanding the structural basis for the conformational changes accompanying the substrate-transportation cycle, we have studied the C-terminal nucleotide-binding domain of ABCB6 (ABCB6-C) in both the nucleotide-free and ADP-bound states by heteronuclear multidimensional NMR and homology modelling. A non-linear sampling scheme was utilised for indirectly acquired 13C and 15N dimensions of all 3D triple-resonance NMR experiments, in order to overcome the instability and the low solubility of ABCB6-C. The backbone resonances for approximately 25% of non-proline residues, which are mostly distributed around the functionally important loops and in the Helical domain, were not observed for nucleotide-free form of ABCB6-C. From the pH, temperature and magnetic field strength dependencies of the resonance intensities, we concluded that this incompleteness in the assignments is mainly due to the exchange between multiple conformations at an intermediate rate on the NMR timescale. These localised conformational dynamics remained in ADP-bound ABCB6-C except for the loops responsible for adenine base and α/β-phosphate binding. These results revealed that the localised dynamic cooperativity, which was recently proposed for a prokaryotic ABC MJ1267, also exists in a higher eukaryotic ABC, and is presumably shared by all members of the ABC family. Since the Helical domain is the putative interface to the transmembrane domain, this cooperativity may explain the coupled functions between domains in the substrate-transportation cycle.

Keywords

ABC transportermitochondriaNMRnucleotide recognition

Copyright information

© Springer Science+Business Media, Inc. 2006