Work

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

Year: 1997

Type: article

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.

Source: Proceedings of the National Academy of Sciences

DOI: 10.1073/pnas.94.1.42

Authors: Ze-Sheng Li, Yu-Ping Lu, Rui-Guang Zhen, Mark Szczypka, Dennis J. Thiele, Philip A. Rea

Institutions: University of Michigan, University of Pennsylvania

Language: English

Topic: Heavy Metal Exposure and Toxicity

Subfield: Health, Toxicology and Mutagenesis

Field: Environmental Science

Domain: Physical Sciences

Open Access status: green