The mitochondrial inner membrane protein Lpe10p, a homologue of Mrs2p, is essential for magnesium homeostasis and group II intron splicing in yeast.
The yeast ORF YPL060w/LPE10 encodes a homologue of the mitochondrial protein Mrs2p. These two proteins are 32% identical, and have two transmembrane domains in their C-terminal regions and a putative magnesium transporter signature, Y/F-G-M-N, at the end of one of these domains. Data presented here indicate that Lpe10p is inserted into the inner mitochondrial membrane with both termini oriented towards the matrix space. Disruption of the LPE10 gene results in a growth defect on non-fermentable substrates (petite phenotype) and a marked defect in group II intron splicing. The fact that in intron-less strains lpe10 disruptants also exhibit a petite phenotype indicates that functions other than RNA splicing are affected by the absence of Lpe10p. In the mitochondria, concentrations of magnesium, but not of several other divalent metal ions, are increased when Lpe10p is overexpressed and reduced when it is absent. Magnesium concentrations are raised to normal levels and growth on non-fermentable substrates is partially restored by the expression of CorA, the bacterial magnesium transporter, in the lpe10 disruptant. These features are similar to those previously reported for Mrs2p, suggesting that Lpe10p and Mrs2p are functional homologues. However, they cannot easily substitute for each other. Their roles in magnesium homeostasis and, possibly as a secondary effect, in RNA splicing are discussed.
Vienna Biocenter, Department of Microbiology and Genetics, University of Vienna, Austria.
J
J
Gregan
D M
DM
Bui
R
R
Pillich
M
M
Fink
G
G
Zsurka
R J
RJ
Schweyen
D000595:Amino Acid Sequence; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006706:Homeostasis; D007425:Intracellular Membranes / Q000378:metabolism; D007438:Introns; D007473:Ion Channels; D008274:Magnesium / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000235:genetics*; D016366:Open Reading Frames; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
D005656:Fungal Proteins; D007473:Ion Channels; C423310:Lpe10 protein, S cerevisiae; C114838:MRS2 protein, S cerevisiae; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D008274:Magnesium