Transcriptomic Analysis of Aromatic Amino Acid Biosynthesis Under Nitrogen Starvation in Saccharomyces Cerevisiae

Abstract

Yeast Saccharomyces cerevisiae has been a preferred organism for scientific research on many sensing and signaling processes. Its ability to adapt to changes in reproductive conditions, especially its fermentative properties have made this yeast species an industrially important species. Because of that S. cerevisiae has been genetically modified to create many kinds of beneficial chemicals from biomass. S. cerevisiae cells have the ability to detect the quality of nitrogen sources in their environment. And It has many regulatory mechanisms to utilize alternative nitrogen sources after the favored sources have been depleted. And proline is the least desired nitrogen source for many laboratory yeast strains. Usage of proline results in the slowest growth rates. The yeast S. cerevisiae can only get cellular nitrogen from tryptophan, tyrosine, or phenylalanine. The major products of this catabolism are tryptophol, phenylethanol, and tyrosol, which are elements of the mixture of alcohols known as fusel oil and this makes yeast S. cerevisiae important also in the production of seconder metabolites. Next Generation Sequencing allows deep analysis of gene expression. The effect of growth in media containing poor nitrogen source, proline, on the aromatic amino acid biosynthetic pathway was observed using NGS technologies in this work. According to the transcriptomic analysis results, we found that 14 genes are responsible for aromatic amino acid biosynthesis and 12 genes (ARO1, ARO2, ARO4, ARO7, ARO8, ARO9, PHA2, TRP1, TRP2, TRP3, TRP4, and TYR1) were down-regulated, while 2 genes (ARO3 and TRP1) were up-regulated. In addition, ARO1, ARO2, ARO4, ARO7, ARO9, PHA2, TRP1, TRP2, TRP3, TRP4, and TYR1 genes have showed 1.5-fold or more expression.