The yeast ζ-crystallin/NADPH:quinone oxidoreductase (Zta1p) is under nutritional control by the target of rapamycin pathway and is involved in the regulation of argininosuccinate lyase mRNA half-life.

The yeast ζ-crystallin (Zta1p) is a quinone oxidoreductase belonging to the ζ-crystallin family, with activity in the reduction of alkenal/alkenone compounds. Various biological functions have been ascribed to the members of this protein family, such as their ability to interact specifically with AU-rich sequences in mRNA, and thus they have been proposed to act as AU-rich element-binding proteins (AREBPs). In this study, we evaluated the specificity of Zta1p for RNA versus DNA by means of a novel nonisotopic method for the in vitro quantitative detection of protein · RNA complexes. Through comparative transcriptomic analysis, we found that the lack of Zta1p negatively affects the expression of a group of genes involved in amino acid biosynthesis, the argininosuccinate lyase (ARG4) gene being one of them. Here, we propose that Zta1p participates in the post-transcriptional regulation of ARG4 expression by increasing the ARG4 mRNA half-life. In addition, expression of the ζ-crystallin gene (ZTA1) is itself regulated by nutrient availability through the general amino acid control and target of rapamycin pathways. Our results shed new light on the ζ-crystallin family members from yeast to humans as stress response proteins with a bifunctional role in the detoxification of alkenal and alkenone compounds, and the regulation of gene expression.