Functional expression of the multi-subunit type calcium/proton antiporter from Thermomicrobium roseum

Authors

  • Masato Morino,

    1. Graduate School of Life Sciences, Toyo University, Oura-gun, Gunma, Japan
    Current affiliation:
    1. Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, NY, USA
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  • Masahiro Ito

    Corresponding author
    1. Bio-nano Electronics Research Center, Toyo University, Kawagoe, Saitama, Japan
    • Graduate School of Life Sciences, Toyo University, Oura-gun, Gunma, Japan
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Correspondence: Masahiro Ito, Faculty of Life Sciences, Toyo University 1-1-1 Izumino, Itakura-machi, Oura-gun, Gunma 374-0193, Japan. Tel.: +81 276 82 9202; fax: +81 276 82 9801; e-mail: masahiro.ito@toyo.jp

Abstract

Multiple resistance and pH adaptation (Mrp) antiporters are widely distributed in various prokaryotes and have been reported to function as a hetero-oligomeric monovalent cation/proton antiporter, which exchanges a cytoplasmic monovalent cation (Na+, Li+, and/or K+) with extracellular H+. In many organisms, they are essential for survival in alkaline or saline environments. Here, we report that the Mrp antiporter from the thermophilic gram-negative bacterium, Thermomicrobium roseum, does not catalyze monovalent cation/proton antiport like the Mrp antiporters studied to date, but catalyzes Ca2+/H+ antiport in Escherichia coli membrane vesicles.

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