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A member of a novel Arabidopsis thaliana gene family of candidate Mg 2+ ion transporters complements a yeast mitochondrial group II intron‐splicing mutant
Author(s) -
Schock Irene,
Gregan Juraj,
Steinhauser Siegfried,
Schweyen Rudolf,
Brennicke Axel,
Knoop Volker
Publication year - 2000
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2000.00895.x
Subject(s) - complementation , arabidopsis thaliana , arabidopsis , biology , intron , mutant , rna splicing , genetics , yeast , gene , saccharomyces cerevisiae , bimolecular fluorescence complementation , fusion protein , rna , recombinant dna
Summary Autocatalytic activity of some group II introns has been demonstrated in vitro , but helper functions such as the yeast MRS2 protein are essential for splicing in vivo . In our search for such helper factors in plants, we pursued the cloning of two Arabidopsis thaliana homologues, atmrs2‐1 and atmrs2‐2 . Atmrs2‐1 , but not atmrs2‐2 , complements the yeast deletion mutant of mrs2 , and this is congruent with the prediction of two adjacent transmembrane stretches in AtMRS2‐1 and yeast MRS2 but not in AtMRS2‐2. This complementation depends on fusion of the native yeast mitochondrial import sequence to atmrs2‐1 . A differing, non‐mitochondrial, cellular targeting in Arabidopsis is supported by the analysis of green fluorescent protein fusion constructs after transient transformation into plant protoplasts. Further members of what now appears to be a family of 10 mrs2 homologues are identified in the Arabidopsis genome. Similarity searches with the psi ‐ blast algorithm in the protein database fail to identify homologues of this novel gene family in any eukaryotes other than yeasts, but do identify its distant relatedness to the corA group of bacterial magnesium transporters. In line with this observation, intramitochondrial magnesium concentrations are indeed restored to wild‐type levels in the yeast mutant on complementation with atmrs2‐1 .