The Zrc1 is involved in zinc transport system between vacuole and cytosol in Saccharomyces cerevisiae.
The ZRC1 gene encodes a multicopy suppressor of zinc toxicity in Saccharomyces cerevisiae; however, previously we found that the expression of ZRC1 was induced when the intracellular zinc level was decreased. Zrc1 has six putative transmembrane domains and we determined that a Zrc1-GFP fusion protein was localized to the vacuolar membrane. The steady state level of intracellular zinc in a zrc1Delta mutant cultured in the zinc-abundant medium was lower than that in wild type. No distinct difference was observed in the basal activity of glyoxalase I, which is a cytosolic enzyme requiring zinc for catalytic function and is used here as a marker for cytosolic zinc-availability, between wild type and zrc1Delta mutant, although the activity was decreased much greater extent in the zrc1Delta mutant if the cells were exposed to the metal-limited medium. Similarly, the basal expression level of ZRC1-lacZ reporter gene in zrc1Delta mutant was the same as that in wild type; however, the fold of induction of ZRC1-lacZ expression in zrc1Delta mutant under the zinc-limited conditions was higher than that in the wild type. Based on these results, we present a tentative model for the function of Zrc1 as a mechanism to maintain the zinc homeostasis in yeast.
Miyabe
S
S
Research Institute for Food Science, Kyoto University, Uji, Kyoto, 611-0011, Japan
Izawa
S
S
Inoue
Y
Y
D001483:Base Sequence; D001692:Biological Transport; D027682:Cation Transport Proteins; D003600:Cytosol / Q000378:metabolism*; D017931:DNA Primers; D005656:Fungal Proteins / Q000502:physiology*; D006706:Homeostasis; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014617:Vacuoles / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
D027682:Cation Transport Proteins; D017931:DNA Primers; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C088843:ZRC1 protein, S cerevisiae; D015032:Zinc