The mitochondrial inner membrane protein Lpe10p, a homologue of Mrs2p, is essential for magnesium homeostasis and group II intron splicing in yeast

Abstract

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.

MNR2 Regulates Intracellular Magnesium Storage in Saccharomyces cerevisiae

“…Previous reports indicated that both the Mrs2 and the Lpe10 proteins were essential for Mg uptake by mitochondria, as lpe10 and mrs2 mutants displayed a similar decrease in mitochondrial Mg content (Gregan et al 2001a;Kolisek et al 2003). To determine the effect of these mutations on whole-cell Mg content, we grew strains carrying combinations of mnr2, lpe10, and mrs2 mutations in Mgreplete and -deficient conditions.…”

“…NP174, NP180, NP193, and NP201 were generated by sequential transformation of DY1514 with the insert of pmnr2SpHIS5 and a tfp1TKAN R PCR product, followed by sporulation. NP103, NP107, and NP112 were derived by transformation of DBY747, and lpe10D-1 and mrs2D-2 (Gregan et al 2001a) with the mnr2TKAN R PCR product. AAS and inductively coupled plasma-mass spectrometry: Measurement of total cell-associated Mg was routinely performed using AAS.…”

Antagonistic signals within the COX2 mRNA coding sequence control its translation in Saccharomyces cerevisiae mitochondria

“…MRS2 encodes a mitochondrial inner membrane protein that functions as a magnesium transporter (Bui et al 1999;Gregan et al 2001) and is required for splicing of mito- cox2 (1,15,(89)(90)(91) cox2 (1,(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(89)(90)(91) cox2 (1,(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(89)(90)(91) cox2 (1,(17)(18)(19)(20)(21)(22)(23)(24)(25)(89)(90)(91) cox2 (1,(18)(19)(20)(21)(22)(23)(24)(25)(89)(90)(91) cox2 (1,…”

The Role of Mg(II) in DNA Cleavage Site Recognition in Group II Intron Ribozymes

“…Moreover, several metal ion binding sites have been located in the active site (38 -40), and a two-metal ion mechanism (41,42) has been suggested to underlie intron catalysis (43,44). In-cell studies establishing a correlation between the intracellular Mg 2ϩ concentration and the frequency of splicing and retrohoming buttress the relevance of Mg 2ϩ for group II intron catalysis (45)(46)(47)(48). The importance of the identity of the divalent metal ions bound to the intron is underscored by the finding that the presence of Mn 2ϩ can lead to a shift of the cleavage site (49) and that already low amounts of Ca 2ϩ decrease the turnover rate by 50% in the Sc.ai5␥ intron (50).…”