Solution structure of a novel calcium binding protein, MTH1880, from Methanobacterium thermoautotrophicum

Authors

  • Chang-Hun Lee,

    1. Department of Biochemistry, College of Science, Yonsei University, Seoul, Korea, 120-749
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    • These authors equally contributed to this work.

  • Jin-Won Jung,

    1. Department of Biochemistry, College of Science, Yonsei University, Seoul, Korea, 120-749
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    • These authors equally contributed to this work.

  • Adelinda Yee,

    1. Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada M5G 2M9
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  • Cheryl H. Arrowsmith,

    1. Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada M5G 2M9
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  • Weontae Lee

    Corresponding author
    1. Department of Biochemistry, College of Science, Yonsei University, Seoul, Korea, 120-749
    • Department of Biochemistry, College of Science, Yonsei University, 134 Seodaemoon-Gu, Shinchondong, Seoul, Korea 120-749; fax: 82-2-363-2706.
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Abstract

MTH1880 is a hypothetical protein from Methanobacterium thermoautotrophicum, a target organism of structural genomics. The solution structure determined by NMR spectroscopy demonstrates a typical α + β-fold found in many proteins with different functions. The molecular surface of the protein reveals a small, highly acidic pocket comprising loop B (Asp36, Asp37, Asp38), the end of β2 (Glu39), and loop D (Ser57, Ser58, Ser61), indicating that the protein would have a possible cation binding site. The NMR resonances of several amino acids within the acidic binding pocket in MTH1880, shifted upon addition of calcium ion. This calcium binding motif and overall topology of MTH1880 differ from those of other calcium binding proteins. MTH1880 did not show a calcium-induced conformational change typical of calcium sensor proteins. Therefore, we propose that the MTH1880 protein contains a novel motif for calcium-specific binding, and may function as a calcium buffering protein.

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