Understanding Zinc Homeostasis using Loz1 from the Fission Yeast

Understanding Zinc Homeostasis using Loz1 from the Fission Yeast

Bibliographic Details
Main Author: Wilson, Stevin
Language:English
Published: The Ohio State University / OhioLINK 2019
Subjects:
Genetics
Molecular Biology
zinc homeostasis
fission yeast
Schizosaccharomyces pombe
storage organelle
nutrient stress
metal toxicity
gene regulation
DNA binding
transcriptome
nutrient sensing
Loz1
Zap1
Zhf1
Ecl
transcription factor
ChIP-seq
RNA-seq
MTF-1
transporter
zinc fingers
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=osu1565902886663748
id ndltd-OhioLink-oai-etd.ohiolink.edu-osu1565902886663748
record_format oai_dc
collection NDLTD
language English
sources NDLTD
topic Genetics
Molecular Biology
zinc homeostasis
fission yeast
Schizosaccharomyces pombe
storage organelle
nutrient stress
metal toxicity
gene regulation
DNA binding
transcriptome
nutrient sensing
Loz1
Zap1
Zhf1
Ecl
transcription factor
ChIP-seq
RNA-seq
MTF-1
transporter
zinc fingers
spellingShingle Genetics
Molecular Biology
zinc homeostasis
fission yeast
Schizosaccharomyces pombe
storage organelle
nutrient stress
metal toxicity
gene regulation
DNA binding
transcriptome
nutrient sensing
Loz1
Zap1
Zhf1
Ecl
transcription factor
ChIP-seq
RNA-seq
MTF-1
transporter
zinc fingers
Wilson, Stevin
Understanding Zinc Homeostasis using Loz1 from the Fission Yeast
author Wilson, Stevin
author_facet Wilson, Stevin
author_sort Wilson, Stevin
title Understanding Zinc Homeostasis using Loz1 from the Fission Yeast
title_short Understanding Zinc Homeostasis using Loz1 from the Fission Yeast
title_full Understanding Zinc Homeostasis using Loz1 from the Fission Yeast
title_fullStr Understanding Zinc Homeostasis using Loz1 from the Fission Yeast
title_full_unstemmed Understanding Zinc Homeostasis using Loz1 from the Fission Yeast
title_sort understanding zinc homeostasis using loz1 from the fission yeast
publisher The Ohio State University / OhioLINK
publishDate 2019
url http://rave.ohiolink.edu/etdc/view?acc_num=osu1565902886663748
work_keys_str_mv AT wilsonstevin understandingzinchomeostasisusingloz1fromthefissionyeast
_version_ 1719456346987823104
spelling ndltd-OhioLink-oai-etd.ohiolink.edu-osu15659028866637482021-08-03T07:12:25Z Understanding Zinc Homeostasis using Loz1 from the Fission Yeast Wilson, Stevin Genetics Molecular Biology zinc homeostasis fission yeast Schizosaccharomyces pombe storage organelle nutrient stress metal toxicity gene regulation DNA binding transcriptome nutrient sensing Loz1 Zap1 Zhf1 Ecl transcription factor ChIP-seq RNA-seq MTF-1 transporter zinc fingers <p>Zinc is the second most abundant transition metal in humans and is essential for life. Zinc is required for the activity of more than 300 enzymes spanning the six major classes of enzymes. Also, the coordination of zinc ions confers proper structural conformation to numerous proteins. Given the importance of zinc to cellular metabolism, zinc deficiency is harmful to health. Zinc, in excess, is also toxic to cells. Therefore, all organisms have evolved zinc homeostasis mechanisms to maintain an optimum range of intracellular zinc levels. Zinc-responsive transcriptional regulation is one of the most common means to achieve zinc homeostasis. Transcriptional factors can regulate the expression of zinc transporters, zinc-sequestering proteins, and abundant zinc-binding proteins according to cellular zinc status. Most of our knowledge about the zinc-responsive transcriptional regulation in eukaryotes is derived from Zap1 from <i>Saccharomyces cerevisiae</i> and MTF-1 from vertebrates, which activate gene expression in response to zinc deficiency and excess zinc, respectively. However, there are several questions remaining to be answered, including the regulation of mammalian zinc-regulated genes independent of MTF-1 and the properties that enable proteins to sense intracellular zinc levels. The fission yeast <i>Schizosaccharomyces pombe</i> lacks a Zap1 homolog, and yet regulates gene expression in response to zinc. It was later discovered that Loz1 was required for this zinc-responsive transcriptional regulation of gene expression.</p><p>In this study, I have investigated the role of Loz1 in the zinc-responsive regulatory pathway. The results from this study show that Loz1 is a transcriptional factor that represses the expression of target genes by binding to their promoters under zinc-replete conditions. For the Loz1-mediated regulation <i>in vivo</i>, a Loz1 Response Element (LRE) with the sequence 5’-CGNMRATCNTY-3’ is necessary and sufficient. By combining information about the Loz1 binding loci to the transcriptomic changes that occur in a Loz1-dependent manner, I also determined the Loz1 regulon under zinc-replete growth conditions. By expressing two predicted Loz1 orthologs in <i>S. pombe</i> cells lacking Loz1, I found that these proteins, having the conserved C<sub>2</sub>H<sub>2</sub>-type zinc fingers and divergent accessory domains, retained the ability to regulate the expression of Loz1 target genes in a zinc-dependent manner. </p><p>In the second part of this study, I elucidated the role of the Ecl family proteins in the regulation of two highly regulated Loz1 target genes, <i>zrt1</i> and <i>SPBC1348.06c</i>. I found that the Ecl family-mediated activation of these genes is independent of the zinc-sensing regulatory pathway that contains Loz1. </p><p>In the final chapter of this work, I determined the subcellular localization of Zhf1, which is a zinc transporter that is required for growth under excess zinc. Fluorescence microscopy using GFP-tagged Zhf1 showed a vacuolar membrane localization, which suggests that excess zinc is stored in vacuoles where the bulk of cellular phosphorus is also stored.</p><p>The data presented within this dissertation confirm Loz1 as the first zinc-responsive transcriptional repressor identified in eukaryotes. Since the Loz1 DNA binding <i>in vivo</i> is zinc-dependent and this DNA binding requires the two conserved C-terminal C<sub>2</sub>H<sub>2</sub>-type zinc fingers, our results strongly suggest the zinc-responsive regulatory role to be due to the ability of the Loz1 zinc fingers to `sense’ intracellular zinc status. </p> 2019 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1565902886663748 http://rave.ohiolink.edu/etdc/view?acc_num=osu1565902886663748 restricted--full text unavailable until 2025-12-16 This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

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