Effects of metal ions and hydrogen peroxide on the phenotype of yeast hom6Δ mutant

HOM6 is a major gene in the aspartate pathway which leads to biosynthesis of threonine and methionine. The phenotypes of the gene deletion mutant (hom6∆) in a variety of cultural conditions have previously provided meaningful insights into the biological roles of HOM6 and its upstream intermediate metabolites. Here, we conducted a survey on a spectrum of metal ions for their effect on the aspartate pathway and broader sulphur metabolism. We show that manganese (Mn2+) promoted the growth of hom6∆ under both anaerobic and aerobic conditions. Unexpectedly, 4 mmol l−1 hydrogen peroxide (H2O2), a dose normally causing temporary cell growth arrest, enhanced the growth of hom6∆ under the anaerobic condition only, while it had no effect on the wild type strain BY4743. We propose that Mn2+ and H2O2 promote the growth of hom6∆ by reducing the accumulation of the toxic intermediate metabolite"”aspartate β-semialdehyde, via directing the aspartate pathway to the central sugar metabolism-tricarboxylic acid cycle.