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Oxidative Stress Induced by Loss of Superoxide Dismutases Leads to Activation of No‐Go Decay
Author(s) -
Cianflone Emily,
Champine Madison,
Lobb Amber,
Segal Scott P.
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.05502
Subject(s) - superoxide dismutase , cytoplasm , ribosome , intracellular , oxidative stress , reactive oxygen species , microbiology and biotechnology , chemistry , mitochondrion , biochemistry , oxidative phosphorylation , messenger rna , sod1 , cytosol , enzyme , biology , rna , gene
Reactive oxygen species (ROS) are known to cause oxidative damage in the cell and have been connected to many neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and cancer. Superoxide dismutases (SODs) are a group of enzymes that act to prevent oxidative damage from ROS by converting O 2 − to H 2 O 2 . In Saccharomyces cerevisiae, there are two SOD proteins that are expressed, each of which is conserved in humans. Sod1p is a cytoplasmic Cu/Zn coordinated enzyme, whereas Sod2p coordinates Mn 2+ and localizes to mitochondria. Although there is significant data showing that loss of SOD proteins allows for high levels of intracellular oxidation, it is unknown what effects that would have on the translating pool of mRNA. Current work has revealed that strains lacking Sod1p have a moderate decrease in general translation and an increase in P‐body assembly. Furthermore, this reduction in translation is likely due to the formation of 8‐oxo(G) bases in mRNA, which can cause ribosome stalls leading to the subsequent activation of the No‐Go quality control pathway. No‐Go decay is mediated by the proteins Dom34p and Hbs1p, which act together to remove stalled ribosomes and promote endonucleolytic cleavage of the mRNA at the stall site. The 3′ fragment of mRNA is then localized to P‐bodies to be degraded 5′ to 3′ by Xrn1p, whereas the 5′ fragment is degraded by the cytoplasmic exosome. Sod2p performs a similar role to Sod1p, as it also converts O 2 − to H 2 O 2 , and plays an important role in preventing the formation of strong oxidant peroxynitrate (ONOO − ). Given that it localizes to mitochondria, a loss of Sod2p would result in higher levels of mitochondrially derived ROS. To determine the effect of mitochondrially derived ROS on the translating pool of mRNA, both general translation and P‐body assembly will be analyzed in strains lacking Sod2p. If general translation is reduced and P‐body assembly is increased, then it will be ascertained whether No‐Go Decay is being upregulated in the absence of Sod2p. To perform this analysis, double mutant strains lack both Sod2p and No‐Go Decay will be created and further analyzed for general translational control and P‐body assembly.