Hydrolase regulates NAD+ metabolites and modulates cellular redox

The role of NAD(+) in redox processes is well established. However, the functions of NAD(+) cleavage products like ADPr remain unclear. Prior research has shown that sirtuins generate OAADPr from NAD(+), but the downstream effects are not fully understood. This gap motivated a closer look at enzymes that regulate these metabolites. No prior work had resolved how ADPr and OAADPr influence ROS levels. Understanding these pathways could clarify redox regulation. The study focuses on a specific hydrolase, Ysa1, in yeast. This enzyme’s role in ADPr metabolism had not been fully characterized before this work.

The study aimed to investigate the role of Ysa1 in regulating ADPr and OAADPr levels. The authors wanted to determine how these metabolites affect cellular redox balance. They hypothesized that Ysa1’s activity influences ROS production and resistance. The motivation came from observing ROS-related phenotypes in Deltaysa1 cells. The team sought to link Ysa1’s function to mitochondrial and glycolytic pathways. They also wanted to explore how ADPr affects NADPH production. This work addresses a gap in understanding NAD(+) metabolite functions. The findings may help explain how cells manage oxidative stress.

The researchers used Saccharomyces cerevisiae as a model organism. They created a Deltaysa1 strain to study the enzyme’s role. Metabolite levels were measured using biochemical assays. ROS levels were assessed using fluorescent probes. Mitochondrial function was analyzed with electron transport chain inhibitors. Glycolytic activity was evaluated by measuring enzyme inhibition. The pentose phosphate pathway was monitored for NADPH production. These methods allowed the team to link Ysa1 activity to redox outcomes.

Deltaysa1 cells showed 50% higher ADPr and OAADPr levels. AMP levels dropped correspondingly in these cells. ROS resistance increased in Deltaysa1 compared to wild type. Basal ROS levels were 40% lower in Deltaysa1 cells. ADPr inhibited complex I of the mitochondrial electron transport chain. This inhibition reduced ROS production in the mitochondria. ADPr also inhibited glyceraldehyde-3-phosphate dehydrogenase. This diversion increased NADPH via the pentose phosphate pathway.

The authors propose that Ysa1 regulates ADPr and OAADPr levels. These metabolites modulate cellular redox balance through two pathways. First, ADPr inhibits mitochondrial complex I, lowering ROS production. Second, ADPr inhibits glycolytic enzymes, increasing NADPH. The study suggests that ADPr/OAADPr levels protect cells from oxidative stress. The findings trace directly to the observed ROS resistance in Deltaysa1 cells. The authors do not claim these metabolites are essential for redox regulation. Their conclusions are limited to the mechanisms described in the abstract.