Abstract
Iron plays an essential role in all organisms and is involved in the structure of many biomolecules. It also regulates the Fenton reaction where highly reactive hydroxyl radicals occur. Iron is also important for microbial biodiversity, health and nutrition. Excessive iron levels can cause oxidative damage in cells. Saccharomyces cerevisiae evolved mechanisms to regulate its iron levels. To study the iron stress resistance in S. cerevisiae, evolutionary engineering was employed. The evolved iron stress-resistant mutant “M8FE” was analysed physiologically, transcriptomically and by whole genome re-sequencing. M8FE showed cross-resistance to other transition metals: cobalt, chromium and nickel and seemed to cope with the iron stress by both avoidance and sequestration strategies. PHO84, encoding the high-affinity phosphate transporter, was the most down-regulated gene in the mutant, and may be crucial in iron-resistance. M8FE had upregulated many oxidative stress response, reserve carbohydrate metabolism and mitophagy genes, while ribosome biogenesis genes were downregulated. As a possible result of the induced oxidative stress response genes, lower intracellular oxidation levels were observed. M8FE also had high trehalose and glycerol production levels. Genome re-sequencing analyses revealed several mutations associated with diverse cellular and metabolic processes, like cell division, phosphate-mediated signalling, cell wall integrity and multidrug transporters.
Highlights
IntroductionIron is one of the most commonly found transition metals in the Earth’s crust
After aluminium, iron is one of the most commonly found transition metals in the Earth’s crust
One-color microarray analyses were performed for M8FE and 905, under control and iron stress conditions
Summary
Iron is one of the most commonly found transition metals in the Earth’s crust. As well as in biological systems, iron is most often found in its Fe2+ (ferrous) and Fe3+ (ferric) oxidation states. Most forms of iron found in the environment are insoluble. This property of iron prevents biological systems from accessing this micronutrient. Salt forms are more soluble than other forms. Since the ferrous ion is much more soluble than the ferric ion in the 10−2 M range, it is more toxic than the ferric ion. Ferrous iron is more bioavailable than ferric iron and it is favourable for oxidation to the more stable “ferric” form, which gains iron redox potential [1,2,3]
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