Magnesium ions in yeast: setting free the metabolism from glucose catabolite repression

Abstract

In a recent work we showed that magnesium (Mg) plays an important role in industrial ethanol production, overcoming the negative effect of the excess of minerals, particularly copper, present in sugarcane juice, with a consequent increase in ethanol yield. This cation has been reported to be involved in several steps of yeast metabolism, acting mainly as a co-factor of several enzymes of fermentation metabolism and protecting yeast cells from stressful conditions. However, despite many physiological investigations, its effect in the molecular mechanisms that control such metabolic activities remains unclear and to date no information concerning its influence on gene expression has been provided. The present work took advantage of the DNA microarray technology to analyse the global gene expression in yeast cells upon fermentation in Mg-supplemented medium. The results of the fermentation parameters confirmed the previous report on the increase in ethanol yield by Mg. Moreover, the gene expression data revealed an unexpected set of up-regulated genes currently assigned as being negatively-regulated by glucose, which belong to respiratory and energy metabolism, the stress response and the glyoxalate cycle. On the other hand, genes involved in ribosome biogenesis were down-regulated. Computational analysis provided evidence for a regulatory network commanded by key transcriptional factors that may be responsible for the biological action of Mg in yeast cells. In this scenario, Mg seems to act by reprogramming the yeast metabolism by releasing many genes from glucose catabolite repression with positive consequences for ethanol production and maintenance of cell viability.

Isolation and identification of aroma producing strain with esterification capacity from yellow water

“…Yeast extract and peptone are rich in vitamins, essential amino acids and trace elements such as magnesium cation. Magnesium cation acts as a mainly co-factor of several enzymes of fermentation metabolism and protecting yeast cells from stressful conditions [45]. The yield of EA increased with the elevation of nitrogen source, but excess nitrogen source may also suppress EA production (S2(C) Fig).…”

Magnesium enhances dehydration tolerance in Schizosaccharomyces pombe by promoting intracellular 5′‐methylthioadenosine accumulation

“…In S. cerevisiae cells, the ion Mg 2+ activates over 300 enzymes in different metabolic reactions involved in processes such as the maintenance of cellular integrity, TCA cycle, β‐oxidation, DNA, and ATP synthesis, as well as the structural stabilization of nucleic acids, polysaccharides, and lipids. The ion Mg 2+ binds to ATP molecules at physiological pH, stabilizing phosphate groups used in ATP‐dependent reactions, such as DNA polymerization (Barros de Souza et al, ). Its association to the phospholipids of membranes promotes membrane integrity by decreasing their fluidity, especially under stress conditions (Walker , ).…”

“…Its association to the phospholipids of membranes promotes membrane integrity by decreasing their fluidity, especially under stress conditions (Walker , ). The Mg 2+ ion also participates in S. cerevisiae cell protection by activating detoxification processes for heavy metals (e.g., Al 3+ or Cd 2+ ) and reactive oxygen species (ROS; Barros de Souza et al, ; Udeh et al, ). Moreover, growth of Schizosaccharomyces pombe has been resumed by adding Mg 2+ to cells arrested with the metal chelator‐ionophore A 23187 (Walker, ).…”