COT1, a gene involved in cobalt accumulation in Saccharomyces cerevisiae.

Conklin, Douglas S.; McMaster, J A; Culbertson, Michael R.; Kung, Ching

doi:10.1128/mcb.12.9.3678

Cited by 189 publications

(128 citation statements)

References 28 publications

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“…Whereas previous reports suggested that ZRC1 and COT1 primarily confer tolerance to zinc and cobalt ions respectively (8,12), it is now clear that under certain conditions, these genes are functionally redundant with respect to zinc. Zrc1 and Cot1 are both important determinants of zinc detoxification in zinc-replete yeast grown in high zinc, and both genes were implicated in the vacuolar storage of zinc in zinc-replete cells (13,14).…”

Section: Discussionmentioning

confidence: 77%

“…Our recent in vitro studies provided evidence that Zrc1 directly mediates vacuolar zinc transport, most likely via a zinc/H ϩ antiport mechanism (11). The COT1 gene encodes a related protein that may act analogously to Zrc1 in cobalt detoxification (8,12). Cot1 also contributes to zinc detoxification (13) and both Zrc1 and Cot1 appear to be required for sequestration of zinc in an intracellular storage compartment for later use under zinc-limiting conditions (14).…”

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confidence: 99%

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Induction of the ZRC1 Metal Tolerance Gene in Zinc-limited Yeast Confers Resistance to Zinc Shock

MacDiarmid

Milanick

Eide

2003

Journal of Biological Chemistry

165

125

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Zinc is an essential nutrient but toxic to cells with overaccumulation. For this reason, intracellular zinc levels are tightly controlled. In the yeast Saccharomyces cerevisiae, the Zrc1 and Cot1 proteins have been implicated in the storage and detoxification of excess zinc in the vacuole. Surprisingly, transcription of ZRC1 is induced in zinc-limited cells by the zinc-responsive transcription factor Zap1. We show here that this increase in ZRC1 expression is a novel mechanism of zinc homeostasis and stress tolerance. Zinc-limited cells also express high levels of the plasma membrane zinc uptake transporters. As a consequence, when zinc-limited cells are resupplied with small amounts of zinc, large quantities quickly accumulate in the cell, a condition we refer to as "zinc shock." We show here that ZRC1 and its induction in zinc-limited cells are required for resistance to this zinc shock. Experiments using the zincresponsive fluorophore FuraZin-1 as an indicator of vacuolar zinc levels indicated that Zrc1 is required for the rapid transport of zinc into the vacuole during zinc shock. We also present evidence that cytosolic zinc rises to higher levels in cells unable to sequester this excess zinc. Thus, the increase in ZRC1 expression occurs prior to the zinc shock stress for which this induction is important. We propose that this "proactive" strategy of homeostatic regulation, such as we document here for ZRC1, may represent a common but largely unrecognized phenomenon.

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Section: Discussionmentioning

confidence: 77%

mentioning

confidence: 99%

Induction of the ZRC1 Metal Tolerance Gene in Zinc-limited Yeast Confers Resistance to Zinc Shock

MacDiarmid

Milanick

Eide

2003

Journal of Biological Chemistry

165

125

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“…The Zn-sensitive phenotype of the zrc1 ⌬ mutant was fully complemented by PtdMTP1. cot1 ⌬ mutants are hypersensitive to both Zn and Co, because COT1 mediates the efflux of both ions into the vacuole (Conklin et al, 1992;Li and Kaplan, 1998;Lyons et al, 2000). Interestingly, although PtdMTP1 complemented the cot1 ⌬ mutant phenotype when grown on Zn ( Figures 3C and 3D), PtdMTP1 failed to complement when grown on Co ( Figures 3E and 3F).…”

Section: Expression Of Ptdmtp1 In Yeast Confers Tolerance To Zn But Nmentioning

confidence: 92%

Poplar Metal Tolerance Protein 1 Confers Zinc Tolerance and Is an Oligomeric Vacuolar Zinc Transporter with an Essential Leucine Zipper Motif

et al. 2003

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Cation diffusion facilitator (CDF) proteins are a recently discovered family of cation efflux transporters that might play an essential role in metal homeostasis and tolerance. Here, we describe the identification, characterization, and localization of PtdMTP1, a member of the CDF family from the hybrid poplar Populus trichocarpa ؋ Populus deltoides . PtdMTP1 is expressed constitutively and ubiquitously, although at low levels. Heterologous expression in yeast showed that PtdMTP1 was able to complement the hypersensitivity of mutant strains to Zn but not to other metals, including Cd, Co, Mn, and Ni. PtdMTP1 fused to green fluorescent protein localized to the vacuolar membrane both in yeast and in plant cells, consistent with a function of PtdMTP1 in zinc sequestration. Overexpression of PtdMTP1 in Arabidopsis confers Zn tolerance. We show that PtdMTP1, when expressed in yeast and Arabidopsis, forms homooligomers, a novel feature of CDF members. Oligomer formation is disrupted by reducing agents, indicating possible disulfide bridge formation. PtdMTP1 also contains a conserved Leu zipper motif. Although not necessary for oligomer formation, Leu residues within this motif are required for PtdMTP1 functional activity.

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“…ZnT-1 is an integral membrane protein with a deduced length of 507 aa and is predicted to contain six transmembrane-spanning domains (11). It shares limited homology to the yeast cobalt transporter COT1 (15). The ZnT-1 sequence contains the motif (His-Gly) 8 in the large intracellular loop between membrane-spanning regions 4 and 5.…”

mentioning

confidence: 99%