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Proc Natl Acad Sci U S A. 1997 Jan 7;94(1):42-7.

A new pathway for vacuolar cadmium sequestration in Saccharomyces cerevisiae: YCF1-catalyzed transport of bis(glutathionato)cadmium.

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  • 1Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia 19104, USA.

Abstract

The yeast cadmium factor (YCF1) gene encodes an MgATP-energized glutathione S-conjugate transporter responsible for the vacuolar sequestration of organic compounds after their S-conjugation with glutathione. However, while YCF1 was originally isolated according to its ability to confer resistance to cadmium salts, neither its mode of interaction with Cd2+ nor the relationship between this process and organic glutathione-conjugate transport are known. Here we show through direct comparisons between vacuolar membrane vesicles purified from Saccharomyces cerevisiae strain DTY167, harboring a deletion of the YCF1 gene, and the isogenic wild-type strain DTY165 that YCF1 mediates the MgATP-energized vacuolar accumulation of Cd-glutathione complexes. The substrate requirements, kinetics and Cd2+/glutathione stoichiometry of cadmium uptake and the molecular weight of the transport-active complex demonstrate that YCF1 selectively catalyzes the transport of bis(glutathionato)cadmium (Cd x +GS2). On the basis of these results--the Cd2+ hypersensitivity of DTY167, versus DTY165, cells, the inducibility of YCF1-mediated transport, and the rapidity and spontaneity of Cd-GS2 formation--this new pathway is concluded to contribute substantially to Cd2+ detoxification.

PMID:
8990158
[PubMed - indexed for MEDLINE]
PMCID:
PMC19233
Free PMC Article

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