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Glutathione Transporter (glutathione + transporter)

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Life Sciences100%

Selected Abstracts

Pgt1, a glutathione transporter from the fission yeast Schizosaccharomyces pombe

FEMS YEAST RESEARCH, Issue 6 2008
Anil Thakur
Abstract The Schizosaccharomyces pombe ORF, SPAC29B12.10c, a predicted member of the oligopeptide transporter (OPT) family, was identified as a gene encoding the S. pombe glutathione transporter (Pgt1) by a genetic strategy that exploited the requirement of the cys1a, strain of S. pombe (which is defective in cysteine biosynthesis) for either cysteine or glutathione, for growth. Disruption of the ORF in the cys1a, strain led to an inability to grow on glutathione as a source of cysteine. Cloning and subsequent biochemical characterization of the ORF revealed that a high-affinity transporter for glutathione (Km=63 ,M) that was found to be localized to the plasma membrane. The transporter was specific for glutathione, as significant inhibition in glutathione uptake could be observed only by either reduced or oxidized glutathione, or glutathione conjugates, but not by dipeptides or tripeptides. Furthermore, although glu,cys,gly, an analogue of glutathione (,-glu,cys,gly), could be utilized as a sulphur source, the growth was not Pgt1 dependent. This further underlined the specificity of this transporter for glutathione. The strong repression of pgt1+ expression by cysteine suggested a role in scavenging glutathione from the extracellular environment for the maintenance of sulphur homeostasis in this yeast. [source]

Functional characterization and expression analysis of a glutathione transporter, BjGT1, from Brassica juncea: evidence for regulation by heavy metal exposure

PLANT CELL & ENVIRONMENT, Issue 10 2003
J. BOGS
ABSTRACT Glutathione and its derivatives play an important role in the tolerance of plants against heavy metals. A glutathione transporter, BjGT1 (AJ561120), was cloned and functionally characterized from Brassica juncea, a plant which may be used for phytoremediation. The full-length BjGT1 cDNA showed homology with the high affinity glutathione transporter HGT1 from Saccharomyces cerevisiae and shares 92% identity with a putative glutathione transporter from A. thaliana (At4g16370). When expressed in the S. cerevisiae hgt1, strain, BjGT1 complemented the mutant on medium with glutathione as the only sulphur source and mediated the uptake of [3H]GSH. Immunoblot analysis with a peptide-specific antiserum directed against a C-terminal sequence revealed high BjGT1 expression in leaf tissue and relatively low expression in stem tissue, whereas BjGT1 protein was not detectable in root tissue. The amounts of BjGT1 mRNA and protein were analysed during a 6 d exposure of B. juncea to 25 µm Cd(NO3)2. BjGT1 mRNA was strongly induced by cadmium in stems and leaves. Unexpectedly, the amount of BjGT1 protein in leaves showed a pronounced decrease with a minimum after 96 h of Cd exposure, followed by partial recovery. The strong regulation of BjGT1 by cadmium suggests a role of this glutathione transporter during heavy metal exposure. [source]