Zinc is an essential nutrient but also potentially toxic if accumulated to excess. Therefore, cells have evolved with efficient mechanisms to maintain zinc homeostasis. In addition, cells can alter specific metabolic processes to adapt to the stress of zinc deficiency. Among eukaryotes, these mechanisms of zinc homeostasis and low zinc adaptation are best understood in the yeast Saccharomyces cerevisiae. In yeast, the Zap1 transcription factor is the central regulator of zinc homeostasis. Zap1 activates expression of its target genes in zinc-limited cells and its activity is repressed in replete cells. Over the years, synergistic approach of characterizing the molecular mechanisms of Zap1's zinc responsiveness, combined with analyzing the function of Zap1 target genes, has led to many key discoveries about how cells survive the stress of zinc deficiency. In this application, two specific aims are proposed.
In Specific Aim 1, the Zap1 transcription factor will be further characterized. New Zap1 target genes will be identified and candidate genes previously identified by transcriptomics will be verified as bona fide targets. The role of Zap1 autoregulatio in establishing the regulatory hierarchy of Zap1 target genes will be determined and the mechanism regulating Zap1 DNA binding in response to zinc will be dissected.
In Specific Aim 2, the function of key Zap1 target genes in zinc-limited cells will be characterized. A focus of th next funding period is the Tsa1 chaperone. Functional genomics studies and specific analysis of Tsa1 have indicated that zinc-deficient cells experience a crisis of protein homeostasis. The source of unfolded proteins in zinc-limited cells will be determined as will the mechanisms of protein folding, degradation, and sequestration that cells use to survive. Preliminary results also indicate that Tsa1 orthologs in humans are critical for low zinc growth and their roles in human cells will also be investigated. Health relevance: The long-term goal of the proposed research is to determine how cells respond and adapt to the stress of zinc deficiency, a common nutrient deficiency in the US and the world. The research also explores the effect of zinc deficiency on protein folding and this work may ultimately lead to fundamental insights into diseases of protein misfolding such as amyotrophic lateral sclerosis (ALS), Parkinson's, Alzheimer's, and prion diseases and their relationships with metal homeostasis.

Public Health Relevance

Zinc is an essential nutrient but also toxic so cells require mechanisms to maintain zinc homeostasis and adapt to zinc-deficient conditions. This proposed research investigates these mechanisms and explores the effect of zinc deficiency on protein folding which may ultimately link zinc deficiency with diseases of protein misfolding, such as amyotrophic lateral sclerosis (ALS), Parkinson's, Alzheimer's, and prion diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM056285-16A1
Application #
8758937
Study Section
Macromolecular Structure and Function A Study Section (MSFA)
Program Officer
Anderson, Vernon
Project Start
1997-09-30
Project End
2018-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
16
Fiscal Year
2014
Total Cost
$333,175
Indirect Cost
$113,175
Name
University of Wisconsin Madison
Department
Nutrition
Type
Schools of Earth Sciences/Natur
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
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Wu, Yi-Hsuan; Frey, Avery G; Eide, David J (2011) Transcriptional regulation of the Zrg17 zinc transporter of the yeast secretory pathway. Biochem J 435:259-66
Atkinson, Aaron; Khalimonchuk, Oleh; Smith, Pamela et al. (2010) Mzm1 influences a labile pool of mitochondrial zinc important for respiratory function. J Biol Chem 285:19450-9
Wu, Chang-Yi; Steffen, Janet; Eide, David J (2009) Cytosolic superoxide dismutase (SOD1) is critical for tolerating the oxidative stress of zinc deficiency in yeast. PLoS One 4:e7061

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