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Báo cáo khoa học: Mutational analysis of functional domains in Mrs2p, the mitochondrial Mg2+ channel protein of Saccharomyces cerevisiae

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Mutational analysis of functional domains in Mrs2p, the mitochondrial Mg2+ chanThe nuclear geneMRS2in Saccharomyces cerevisiaeencodes an integral protein (Mrs2p) of the inner mitochondrial membrane. It forms an ion channel mediating influx of Mg 2+ into mitochondria. Orthologues of Mrs2p have been shown to exist in other lower eukaryotes, in vertebrates and in plants.nel protein of Saccharomyces cerevisiae ` Julian Weghuber, Frank Dieterich, Elisabeth M. Froschauer, Sona Svidova and Rudolf J. Schweyen Max F. Perutz Laboratories, Department of Genetics, University of Vienna, Austria Keywords gain-of-function; mag-fura 2; Mg2+; mitochondria; mutagenesis Correspondence R.J. Schweyen, Max F. Perutz Laboratories, Department of Genetics, University of Vienna, Dr. Bohrgasse 9, 1030, Austria Fax: +43. | iFEBS Journal Mutational analysis of functional domains in Mrs2p the mitochondrial Mg2 channel protein of Saccharomyces cerevisiae Julian Weghuber Frank Dieterich Elisabeth M. Froschauer Sona Svidova and Rudolf J. Schweyen Max F. Perutz Laboratories Department of Genetics University of Vienna Austria Keywords gain-of-function mag-fura 2 Mg2 mitochondria mutagenesis Correspondence R.J. Schweyen Max F. Perutz Laboratories Department of Genetics University of Vienna Dr. Bohrgasse 9 1030 Austria Fax 43 14277 9546 Tel 43 14277 54604 Email rudolf.schweyen@univie.ac.at Received 29 November 2005 revised 20 January 2006 accepted 27 January 2006 doi 10.1111 j.1742-4658.2006.05157.x The nuclear gene MRS2 in Saccharomyces cerevisiae encodes an integral protein Mrs2p of the inner mitochondrial membrane. It forms an ion channel mediating influx of Mg2 into mitochondria. Orthologues of Mrs2p have been shown to exist in other lower eukaryotes in vertebrates and in plants. Characteristic features of the Mrs2 protein family and the distantly related CorA proteins of bacteria are the presence of two adjacent transmembrane domains near the C terminus of Mrs2p one of which ends with a F Y-G-M-N motif. Two coiled-coil domains and several conserved primary sequence blocks in the central part of Mrs2p are identified here as additional characteristics of the Mrs2p family. Gain-of-function mutations obtained upon random mutagenesis map to these conserved sequence blocks. They lead to moderate increases in mitochondrial Mg2 concentrations and concomitant positive effects on splicing of mutant group II intron RNA. Site-directed mutations in several conserved sequences reduce Mrs2p-mediated Mg2 uptake. Mutants with strong effects on mitochondrial Mg2 concentrations also have decreased group II intron splicing. Deletion of a nonconserved basic region previously invoked for interaction with mitochondrial introns lowers intramitochondrial Mg2 levels as well as group II intron splicing. Data .