Ubiquitin protease Ubp8 is necessary for S. cerevisiae respiration

Abstract

Healthy mitochondria are required in cell metabolism and deregulation of underlying mechanisms is often involved in human diseases and neurological disorders. Post-translational modifications of mitochondrial proteins regulate their function and activity, accordingly, impairment of ubiquitin proteasome system affects mitochondria homeostasis and organelle dynamics. In the present study we have investigated the role of the ubiquitin protease Ubp8 in S. cerevisiae respiration. We show that Ubp8 is necessary for respiration and its expression is upregulated in glycerol respiratory medium. In addition, we show that the respiratory defects in absence of Ubp8 are efficiently rescued by disruption of the E3 Ub-ligase Psh1, suggesting their epistatic link. Interestingly, we found also that Ubp8 is localized into mitochondria as single protein independently of SAGA complex assembly, thus suggesting an independent function from the nuclear one. We also show evidences on the importance of HAT Gcn5 in sustaining Ubp8 expression and affecting the amount of protein in mitochondria. Collectively, our results have investigated the role of Ubp8 in respiratory metabolism and highlight the role of ubiquitin related pathways in the mitochondrial functions of S. cerevisiae.

Gcn5 and Ubp8 dependent ubiquitylation affects glycolysis in yeast

“…Growth was severely impaired in 0,2% glucose accordingly, an extremely low fermentative potential was correlated to the exclusive presence of Adh1 (Fig. 5C) in ubp8 strain demonstrating its full inability to switch to respiratory conditions as reported in a previous reports [6]. On the contrary, gcn5 strain displayed weak amount of Adh2 in fermentative conditions (2% glucose) suggesting the rerouting of the glycolytic flux towards a respiro-fermentative metabolism (Fig.…”

“…We previously demonstrated the genetic interaction between Gcn5 and Ubp8 in respiratory growth conditions [6,12]. Here we have assayed S.cerevisiae gcn5∆, ubp8∆ and ubp8∆/gcn5∆ strains and confirmed their genetic interaction by growing at low (12°C), physiological (28°C) and high (35°C) temperatures ( Fig.…”

“…The coexistence in SAGA complex of acetylation and deubiquitylation modules sustains their possible interdependency and interlaced functions. Gcn5 and Ubp8 indeed showed functional interaction in fermentative or respiratory growth conditions [6] and at high and low temperatures previously reported to be correlated with glycolysis [7]. In the present study we investigated polyubiquitylated proteins expressed in absence of KAT-Gcn5, DUB-Ubp8 or both in comparison with wild type strains.…”

“…It was reported that, PTMs regulate central carbon metabolism, glycolysis and fermentation where a high number of key enzymes engaged in sugar utilization and energy supply were marked by phosphorylation, acetylation and ubiquitylation indicating a direct involvement of PTMs in the regulation of their catalytic activity [11]. In addition, we have recently demonstrated that Gcn5 and Ubp8 beside their role as catalytic subunits of SAGA complex, are also involved in the control of the respiratory metabolism and mitochondrial functions [6,12]. Following this line of reasoning and starting from a shotgun proteomic profiles and in vivo phenotypic assays in strains missing Gcn5 and Ubp8 or both we wanted to deeply characterize the composition of differentially ubiquitylated proteins in order to clarify their role and investigate possible correlation with the regulation of sugar metabolism.…”

“…Moreover, most of the Ub-proteins found as differentially expressed in the examined comparisons, although not always with the same levels of abundance, resulted shared and up-represented in absence of Ubp8, Gcn5 and in the double disrupted strain. These evidences can be interpreted as due to modification of lysines that can alternatively be acetylated or ubiquitylated [11], or, even, to a lower expression of Ubp8 in gcn5 strain [6].…”