Mutation in a mitochondrial ribosomal protein causes increased sensitivity to oxygen with decreased longevity in the nematode Caenorhabditis elegans.

Oxygen is essential for animals, but high concentrations of oxygen are toxic to them probably because of an increase in reactive oxygen species (ROS). Many genes are involved in the reactions from which ROS are generated, but not much attention has been focused on them. To identify these genes, we screened for mutants with an altered sensitivity to oxidative stress in the nematode Caenorhabditis elegans and isolated a mutant, oxy-5(qa5002). oxy-5 showed an increased sensitivity to oxygen and decreased longevity. The decreased life span in oxy-5 was probably due to increased oxidative stress because it was recovered to a normal level when oxy-5 was cultured under hypoxic conditions. Our genetic analysis has revealed that the responsible gene for oxy-5 encodes a protein similar to mitochondrial ribosomal protein S36. The OXY-5 protein was highly expressed in the neurons, pharynx, and intestine, and expression of oxy-5 from the pan-neuronal H20 promoter efficiently suppressed the increased sensitivity to oxygen in oxy-5. These findings suggested that oxy-5 played an important role in the regulation of the sensitivity to oxygen in neuronal cells in C. elegans.