Cu/Zn superoxide dismutase and the proton ATPase Pma1p of  Saccharomyces cerevisiae

Abstract

In eukaryotes, the Cu/Zn containing superoxide dismutase (SOD1) plays a critical role in oxidative stress protection as well as in signaling. We recently demonstrated a function for S. cerevisiae Sod1p in signaling through CK1γ casein kinases and identified the essential proton ATPase Pma1p as one likely target. The connection between Sod1p and Pma1p was explored further by testing the impact of sod1Δ mutations on cells expressing mutant alleles of Pma1p that alter activity and/or post-translational regulation of this ATPase. We report here that sod1Δ mutations are lethal when combined with the T912D allele of Pma1p in the C-terminal regulatory domain. This “synthetic lethality” was reversed by intragenic suppressor mutations in Pma1p, including an A906G substitution that lies within the C-terminal regulatory domain and hyper-activates Pma1p. Surprisingly the effect of sod1Δ mutations on Pma1-T912D is not mediated through the Sod1p signaling pathway involving the CK1γ casein kinases. Rather, Sod1p sustains life of cells expressing Pma1-T912D through oxidative stress protection. The synthetic lethality of sod1Δ Pma1-T912D cells is suppressed by growing cells under low oxygen conditions or by treatments with manganese-based antioxidants. We now propose a model in which Sod1p maximizes Pma1p activity in two ways: one involving signaling through CK1γ casein kinases and an independent role for Sod1p in oxidative stress protection.

Sod1 integrates oxygen availability to redox regulate NADPH production and the thiol redoxome

“…In response to glucose, sod1 Δ cells exhibit more rapid rates of intracellular acidification, indicating that glycolysis is more active compared to WT cells. In contrast, sod1 Δ cells exhibit a diminished rate of realkalization, indicating that Pma1 is less active in response to glucose, which is consistent with prior work that found that sod1 Δ cells exhibit a defect in Pma1 activity ( 16 , 46 ). To rule out that the intracellular acidification phase is affected by Pma1-dependent realkalization, glucose-dependent changes in intracellular pH were monitored in a strain expressing a hypomorphic allele of PMA1, pma1-tap , containing a C-terminal tandem affinity purification (TAP)-tag ( SI Appendix , Fig.…”

Antioxidant Activity Evaluation of Dietary Flavonoid Hyperoside Using Saccharomyces Cerevisiae as a Model

“…The reaction mixture was incubated in a boiling water bath for 15 min, and the mixture was cooled afterwards. The extracts were used to detect malondialdehyde (MDA) by measuring the absorbance at 532 nm [ 61 , 62 ].…”

Sod1 Integrates Oxygen Availability to Redox Regulate NADPH Production and the Thiol Redoxome

“…Moreover, sod1 Δ cells exhibit slightly diminished rates of re-alkalization, indicating that PMA1 is less active in response to glucose. Indeed, prior work found that sod1 Δ cells exhibit a defect in PMA1 activity (16, 45). To rule out that the intracellular acidification phase is unaffected by PMA1-dependent re-alkalization, glucose-dependent changes in intracellular pH were monitored in a strain expressing a hypomorphic allele of PMA1, pma1-tap , containing a C-terminal tandem affinity purification (TAP)-tag ( Figure S1B ).…”