Evolutionary Engineering of an Iron-Resistant <i>Saccharomyces cerevisiae</i> Mutant and Its Physiological and Molecular Characterization

• Main Authors: Berrak Gülçin Balaban, Ülkü Yılmaz, Ceren Alkım, Alican Topaloğlu, Halil İbrahim Kısakesen, Can Holyavkin, Zeynep Petek Çakar
• Format: Article
• Language: English
• Published: MDPI AG 2019-12-01
• Series: Microorganisms
• Subjects: oxidative stress; evolutionary engineering; stress resistance; <i>saccharomyces cerevisiae</i>; transition metals; iron stress; <i>pho84</i>; adaptive laboratory evolution
• Online Access: https://www.mdpi.com/2076-2607/8/1/43

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. <i>Saccharomyces cerevisiae</i> evolved mechanisms to regulate its iron levels. To study the iron stress resistance in <i>S. cerevisiae</i>, evolutionary engineering was employed. The evolved iron stress-resistant mutant &#8220;<i>M8FE</i>&#8221; was analysed physiologically, transcriptomically and by whole genome re-sequencing. <i>M8FE</i> 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. <i>PHO84</i>, encoding the high-affinity phosphate transporter, was the most down-regulated gene in the mutant, and may be crucial in iron-resistance. <i>M8FE</i> 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. <i>M8FE</i> 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.