0000000000088409
AUTHOR
Rosa De Llanos
Soybean Ferritin Expression in Saccharomyces cerevisiae Modulates Iron Accumulation and Resistance to Elevated Iron Concentrations
Fungi, including the yeast Saccharomyces cerevisiae, lack ferritin and use vacuoles as iron storage organelles. This work explored how plant ferritin expression influenced baker's yeast iron metabolism. Soybean seed ferritin H1 (SFerH1) and SFerH2 genes were cloned and expressed in yeast cells. Both soybean ferritins assembled as multimeric complexes, which bound yeast intracellular iron in vivo and, consequently, induced the activation of the genes expressed during iron scarcity. Soybean ferritin protected yeast cells that lacked the Ccc1 vacuolar iron detoxification transporter from toxic iron levels by reducing cellular oxidation, thus allowing growth at high iron concentrations. Interes…
Responses of Saccharomyces cerevisiae Strains from Different Origins to Elevated Iron Concentrations
ABSTRACT Iron is an essential micronutrient for all eukaryotic organisms. However, the low solubility of ferric iron has tremendously increased the prevalence of iron deficiency anemia, especially in women and children, with dramatic consequences. Baker's yeast Saccharomyces cerevisiae is used as a model eukaryotic organism, a fermentative microorganism, and a feed supplement. In this report, we explore the genetic diversity of 123 wild and domestic strains of S. cerevisiae isolated from different geographical origins and sources to characterize how yeast cells respond to elevated iron concentrations in the environment. By using two different forms of iron, we selected and characterized bot…
Yeast Dun1 Kinase Regulates Ribonucleotide Reductase Inhibitor Sml1 in Response to Iron Deficiency
Iron is an essential micronutrient for all eukaryotic organisms because it participates as a redox-active cofactor in many biological processes, including DNA replication and repair. Eukaryotic ribonucleotide reductases (RNRs) are Fe-dependent enzymes that catalyze deoxyribonucleoside diphosphate (dNDP) synthesis. We show here that the levels of the Sml1 protein, a yeast RNR large-subunit inhibitor, specifically decrease in response to both nutritional and genetic Fe deficiencies in a Dun1-dependent but Mec1/Rad53- and Aft1-independent manner. The decline of Sml1 protein levels upon Fe starvation depends on Dun1 forkhead-associated and kinase domains, the 26S proteasome, and the vacuolar pr…
Differences in activation of MAP kinases and variability in the polyglutamine tract of Slt2 in clinical and non-clinical isolates of Saccharomyces cerevisiae
The concept of Saccharomyces cerevisiae as an emerging opportunistic pathogen is relatively new and it is due to an increasing number of human infections during the past 20 years. There are still few studies addressing the mechanisms of infection of this yeast species. Moreover, little is known about how S. cerevisiae cells sense and respond to the harsh conditions imposed by the host, and whether this response is different between clinical isolates and non-pathogenic strains. In this regard, mitogen-activated protein kinase (MAPK) pathways constitute one of the major mechanisms for controlling transcriptional responses and, in some cases, virulence in fungi. Here we show differences among …
Post-Transcriptional Regulation of Iron Homeostasis in Saccharomyces cerevisiae
Iron is an essential micronutrient for all eukaryotic organisms because it participates as a redox cofactor in a wide variety of biological processes. Recent studies in Saccharomyces cerevisiae have shown that in response to iron deficiency, an RNA-binding protein denoted Cth2 coordinates a global metabolic rearrangement that aims to optimize iron utilization. The Cth2 protein contains two Cx8Cx5Cx3H tandem zinc fingers (TZFs) that specifically bind to adenosine/uridine-rich elements within the 3' untranslated region of many mRNAs to promote their degradation. The Cth2 protein shuttles between the nucleus and the cytoplasm. Once inside the nucleus, Cth2 binds target mRNAs and stimulate…
Use of Saccharomyces cerevisiae and Caenorhabditis elegans as model organisms to study the effect of cocoa polyphenols in the resistance to oxidative stress.
Developing functional foods to improve the quality of life for elderly people has great economic and social impact. Searching for and validating ingredients with in vivo antioxidant effects is one of the key steps in developing this kind of food. Here we describe the combined use of simple biological models and transcriptomics to define the functional intracellular molecular targets of a polyphenol-enriched cocoa powder. Cocoa powder supplemented culture medium led to increased resistance to oxidative stress, in both the budding yeast Saccharomyces cerevisiae and the nematode Caenorhabditis elegans, and, in the latter, lifespan was also increased. These effects are fully dependent on the po…