Fachbereich Veterinärmedizin



    Mrs2p is an essential component of the major electrophoretic Mg2+ influx system in mitochondria (2003)

    Zeitschriftenartikel / wissenschaftlicher Beitrag
    Kolisek, Martin
    Zsurka, Gabor
    Samaj, Jozef
    Weghuber, Julian
    Schweyen, Rudolf J
    Schweigel, Monika
    The EMBO journal; 22(6) — S. 1235–1244
    ISSN: 0261-4189
    Pubmed: 12628916
    Institut für Veterinär-Physiologie

    Oertzenweg 19 b
    14163 Berlin
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    Abstract / Zusammenfassung

    Steady-state concentrations of mitochondrial Mg(2+) previously have been shown to vary with the expression of Mrs2p, a component of the inner mitochondrial membrane with two transmembrane domains. While its structural and functional similarity to the bacterial Mg(2+) transport protein CorA suggested a role for Mrs2p in Mg(2+) influx into the organelle, other functions in cation homeostasis could not be excluded. Making use of the fluorescent dye mag-fura 2 to measure free Mg(2+) concentrations continuously, we describe here a high capacity, rapid Mg(2+) influx system in isolated yeast mitochondria, driven by the mitochondrial membrane potential Deltapsi and inhibited by cobalt(III)hexaammine. Overexpression of Mrs2p increases influx rates 5-fold, while the deletion of the MRS2 gene abolishes this high capacity Mg(2+) influx. Mg(2+) efflux from isolated mitochondria, observed with low Deltapsi only, also requires the presence of Mrs2p. Cross-linking experiments revealed the presence of Mrs2p-containing complexes in the mitochondrial membrane, probably constituting Mrs2p homo- oligomers. Taken together, these findings characterize Mrs2p as the first molecularly identified metal ion channel protein in the inner mitochondrial membrane.