Fachbereich Veterinärmedizin



    The G-M-N motif determines ion selectivity in the yeast magnesium channel Mrs2p (2013)

    Zeitschriftenartikel / wissenschaftlicher Beitrag
    Sponder, G. (WE 2)
    Svidová, S.
    Khan, M.B.
    Kolisek, Martin (WE 2)
    Schweyen, R. J.
    Carugo, O.
    Djinovic-Carugo, K.
    Metallomics : integrated biometal science; 5(6) — S. 745–752
    ISSN: 1756-5901
    DOI: 10.1039/c3mt20201a.
    Pubmed: 23686104
    Institut für Veterinär-Physiologie

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    Abstract / Zusammenfassung

    The highly conserved G-M-N motif of the CorA-Mrs2-Alr1 family of Mg(2+) channels has been shown to be essential for Mg(2+) transport. We performed random mutagenesis of the G-M-N sequence of Saccharomyces cerevisiae Mrs2p in an unbiased genetic screen. A large number of mutants still capable of Mg(2+) influx, albeit below the wild-type level, were generated. Growth complementation assays, performed in media supplemented with Ca(2+) or Co(2+) or Mn(2+) or Zn(2+) at varying concentrations, lead to identification of mutants with reduced growth in the presence of Mn(2+) and Zn(2+). We hereby conclude that (1) at least two, but predominantly all three amino acids of the G-M-N motif must be replaced by certain combinations of other amino acids to remain functional, (2) replacement of any single amino acid within the G-M-N motif always impairs the function of Mrs2p, and (3) we show that the G-M-N motif determines ion selectivity, likely in concurrence with the negatively charged loop at the entrance of the channel thereby forming the Mrs2p selectivity filter.