Abstract
The yeast Saccharomyces cerevisiae expressing a cDNA library prepared from Stylosanthes hamata was screened for enhanced Mn(2+) tolerance. From this screen, we identified four related cDNAs that encode membrane-bound proteins of the cation diffusion facilitator (CDF) family. One of these cDNAs (ShMTP1) was investigated in detail and found to confer Mn(2+) tolerance to yeast by internal sequestration rather than by efflux of Mn(2+). Expression of ShMTP1 in a range of yeast mutants suggested that it functions as a proton:Mn(2+) antiporter on the membrane of an internal organelle. Similarly, when expressed in Arabidopsis, ShMTP1 conferred Mn(2+) tolerance through internal sequestration. The ShMTP1 protein fused to green fluorescent protein was localized to the tonoplast of Arabidopsis cells but appeared to localize to the endoplasmic reticulum of yeast. We suggest that the ShMTP1 proteins are members of the CDF family involved in conferring Mn(2+) tolerance and that at least one of these proteins (ShMTP1) confers tolerance by sequestering Mn(2+) into internal organelles.
MeSH terms
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Adaptation, Physiological / genetics
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Amino Acid Sequence
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Arabidopsis / genetics
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Arabidopsis / metabolism
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Cation Transport Proteins / genetics*
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Cation Transport Proteins / metabolism
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DNA, Complementary / chemistry
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DNA, Complementary / genetics
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DNA, Complementary / isolation & purification
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Endoplasmic Reticulum / genetics
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Endoplasmic Reticulum / metabolism
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Fabaceae / genetics*
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Fabaceae / metabolism
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Gene Expression
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Gene Expression Regulation, Plant / drug effects
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Green Fluorescent Proteins
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Luminescent Proteins / genetics
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Luminescent Proteins / metabolism
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Manganese / metabolism*
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Manganese / pharmacology
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Molecular Sequence Data
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Phylogeny
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Plant Proteins / genetics*
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Plant Proteins / metabolism
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Plants, Genetically Modified
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Protein Isoforms / genetics
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Protein Isoforms / metabolism
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Sequence Analysis, DNA
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Sequence Homology, Amino Acid
Substances
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Cation Transport Proteins
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DNA, Complementary
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Luminescent Proteins
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Plant Proteins
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Protein Isoforms
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Green Fluorescent Proteins
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Manganese
Associated data
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GENBANK/AY181256
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GENBANK/AY181257
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GENBANK/AY181258
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GENBANK/AY181259