Open AccessLoss of Zhf and the tightly regulated zinc‐uptake system SpZrt1 in Schizosaccharomyces pombe reveals the delicacy of cellular zinc balance
Author(s) -
Boch Annegret,
Trampczynska Aleksandra,
Simm Claudia,
Taudte Nadine,
Krämer Ute,
Clemens Stephan
Publication year - 2008
Publication title -
fems yeast research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 92
eISSN - 1567-1364
pISSN - 1567-1356
DOI - 10.1111/j.1567-1364.2008.00414.x
Subject(s) - schizosaccharomyces pombe , zinc , biology , micronutrient , cytosol , saccharomyces cerevisiae , transporter , yeast , biochemistry , transport protein , zinc deficiency (plant disorder) , microbiology and biotechnology , chemistry , gene , enzyme , organic chemistry
Zinc is an essential micronutrient, and yet it can be toxic when present in excess. Zinc acquisition and distribution are dependent on tightly controlled transport of Zn 2+ ions. Schizosaccharomyces pombe represents a second eukaryotic model to study cellular metal homeostasis. In several ways its micronutrient metabolism is fundamentally different from Saccharomyces cerevisiae . We identified the first Zn 2+ ‐uptake system in S. pombe and named it SpZrt1. Knock‐out strains for all three ZIP (Zrt, Irt‐like protein) transporters in fission yeast were constructed. Only zrt1 Δ cells were unable to grow at low Zn 2+ and showed reduced 65 Zn 2+ uptake. Elemental profiles revealed a strong decrease in zinc accumulation. Cd 2+ ions inhibited uptake but Fe 2+ or Mn 2+ did not. Both mRNA abundance and protein amount are tightly regulated. Zrt1 activity is rapidly shut down upon transfer of zinc‐deficient cells to zinc‐replete conditions. In cells lacking Zhf, a transporter mediating endoplasmic reticulum storage of zinc, this response is about 100‐fold more sensitive. Thus, removal of excess of zinc from the cytosol is largely Zhf dependent. Moreover, cells deficient for both transporters are no longer able to adjust to changing external Zn 2+ concentrations. Optimal growth is restricted to a narrow range of Zn 2+ concentrations, illustrating the fine balance between micronutrient deficiency and toxicity.