Glucose Metabolism generates ROS that activate NGD to Sustain the Entire Translating Pool
Presenter(s)
Elizabeth Martinez Castro and Kaitlyn Martin
Abstract
Deletions in SDH1 and CYC1 effect the mitochondrial electron transport chain (ETC) by disrupting electron flow. This causes electrons to leave the ETC prematurely before reaching Complex IV, preventing the reduction of oxygen to water. Instead, these electrons react with oxygen to form reactive oxygen species (ROS). While ROS are naturally created during aerobic metabolism, defects in ETC significantly increase oxidative stress. Excess ROS can damage guanine bases found in mRNA, leading to the formation of 8-oxo(G). These 8-oxo(G) bases can stall ribosomes leading to the activation of No-Go Decay (NGD). NGD is an evolutionary conserved mechanism that aids in the degradation of damaged mRNA that contains stalled ribosomes. While a lot is known about the molecular mechanisms of NGD, the reason why this pathway is evolutionarily conserved is unknown. NGD is mediated by the Dom34p/Hbs1p complex which removes stalled ribosomes and promotes cleavage of mRNA at the stall site by the endonuclease Cue2p. The 5’ fragment produced from the cleavage is degraded by the cytoplasmic exosome in the 3’ to 5’ direction. Whereas the 3’ fragment is localized to p-bodies where it gets degraded 5’ to 3’ by Xrn1p. To minimize the possibility of oxidative molecular damage, cells also express superoxide dismutase proteins (Sod1p) in the cytoplasm to breakdown ROS into O2 and H2O2. Previous work has shown there is a relationship between ROS levels and NGD activity. Therefore, it can be hypothesized that defects in ETC, which increase ROS could damage mRNA leading to an activation of NGD and an increase in p-body assembly. The Saccharomyces cerevisiae (baker’s yeast) strain containing double mutations, cyc1D sod1D, showed increased p-body formation, indicating enhanced NGD activity. In contrast, the sdh1D hbs1D mutant demonstrated decreased p-body formation due to its inability to perform NGD because of the deletion in the hbs1 protein.Lastly, analyses of the sdh1D dom34D strain were unable to be performed due to its significant decrease in cell size. The work presented in this research proposes that NGD is an evolutionary conserved mechanism because it functions to preserve the entire translating pool from reactive oxygen species (ROS) potentially generated from ETC leakiness.
College
College of Science & Engineering
Department
Biology
Campus
Winona
First Advisor/Mentor
Scott Segal
Location
Kryzsko Great River Ballroom, Winona, Minnesota; United States
Start Date
4-23-2026 1:00 PM
End Date
4-23-2026 2:00 PM
Presentation Type
Poster Session
Format of Presentation or Performance
In-Person
Session
2a=1pm-2pm
Poster Number
81
Glucose Metabolism generates ROS that activate NGD to Sustain the Entire Translating Pool
Kryzsko Great River Ballroom, Winona, Minnesota; United States
Deletions in SDH1 and CYC1 effect the mitochondrial electron transport chain (ETC) by disrupting electron flow. This causes electrons to leave the ETC prematurely before reaching Complex IV, preventing the reduction of oxygen to water. Instead, these electrons react with oxygen to form reactive oxygen species (ROS). While ROS are naturally created during aerobic metabolism, defects in ETC significantly increase oxidative stress. Excess ROS can damage guanine bases found in mRNA, leading to the formation of 8-oxo(G). These 8-oxo(G) bases can stall ribosomes leading to the activation of No-Go Decay (NGD). NGD is an evolutionary conserved mechanism that aids in the degradation of damaged mRNA that contains stalled ribosomes. While a lot is known about the molecular mechanisms of NGD, the reason why this pathway is evolutionarily conserved is unknown. NGD is mediated by the Dom34p/Hbs1p complex which removes stalled ribosomes and promotes cleavage of mRNA at the stall site by the endonuclease Cue2p. The 5’ fragment produced from the cleavage is degraded by the cytoplasmic exosome in the 3’ to 5’ direction. Whereas the 3’ fragment is localized to p-bodies where it gets degraded 5’ to 3’ by Xrn1p. To minimize the possibility of oxidative molecular damage, cells also express superoxide dismutase proteins (Sod1p) in the cytoplasm to breakdown ROS into O2 and H2O2. Previous work has shown there is a relationship between ROS levels and NGD activity. Therefore, it can be hypothesized that defects in ETC, which increase ROS could damage mRNA leading to an activation of NGD and an increase in p-body assembly. The Saccharomyces cerevisiae (baker’s yeast) strain containing double mutations, cyc1D sod1D, showed increased p-body formation, indicating enhanced NGD activity. In contrast, the sdh1D hbs1D mutant demonstrated decreased p-body formation due to its inability to perform NGD because of the deletion in the hbs1 protein.Lastly, analyses of the sdh1D dom34D strain were unable to be performed due to its significant decrease in cell size. The work presented in this research proposes that NGD is an evolutionary conserved mechanism because it functions to preserve the entire translating pool from reactive oxygen species (ROS) potentially generated from ETC leakiness.
Comments
Martinez Castro, Elizabeth; Martin, Kaitlyn M