Impact of oxidative stress on the function, abundance, and turnover of the Arabidopsis 80S cytosolic ribosome

• Published in: The Plant journal : for cell and molecular biology Vol. 103; no. 1; pp. 128 - 139
• Main Authors: Salih, Karzan J., Duncan, Owen, Li, Lei, O’Leary, Brendan, Fenske, Ricarda, Trösch, Josua, Millar, A. Harvey
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.07.2020
• Subjects: 14C‐leucine assay; 15N‐labelling; Aging; Arabidopsis; Arabidopsis - metabolism; Arabidopsis Proteins - biosynthesis; Arabidopsis thaliana; Cell culture; Cell growth; Cytosol - metabolism; Degradation; Growth rate; Hydrogen peroxide; Hydrogen Peroxide - pharmacology; Labeling; Menadione; multiple reaction monitoring; Oxidation; Oxidative stress; Oxidative Stress - drug effects; Protein biosynthesis; protein content measuring; Protein synthesis; Proteins; Proteomics; Reactive oxygen species; Ribosomal proteins; Ribosomal Proteins - metabolism; ribosome purification; Ribosomes; Ribosomes - metabolism; Turnover rate; turnover study; Vitamin K 3 - pharmacology; Arabidopsis thaliana; 14C-leucine assay; ribosome purification; turnover study; 15N-labelling; multiple reaction monitoring; protein content measuring; oxidative stress
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.14713

SUMMARY Abiotic stress in plants causes accumulation of reactive oxygen species (ROS) leading to the need for new protein synthesis to defend against ROS and to replace existing proteins that are damaged by oxidation. Functional plant ribosomes are critical for these activities, however we know little about the impact of oxidative stress on plant ribosome abundance, turnover, and function. Using Arabidopsis cell culture as a model system, we induced oxidative stress using 1 µm of H2O2 or 5 µm menadione to more than halve cell growth rate and limit total protein content. We show that ribosome content on a total cell protein basis decreased in oxidatively stressed cells. However, overall protein synthesis rates on a ribosome abundance basis showed the resident ribosomes retained their function in oxidatively stressed cells. 15N progressive labelling was used to calculate the rate of ribosome synthesis and degradation to track the fate of 62 r‐proteins. The degradation rates and the synthesis rates of most r‐proteins slowed following oxidative stress leading to an ageing population of ribosomes in stressed cells. However, there were exceptions to this trend; r‐protein RPS14C doubled its degradation rate in both oxidative treatments. Overall, we show that ribosome abundance decreases and their age increases with oxidative stress in line with loss of cell growth rate and total cellular protein amount, but ribosome function of the ageing ribosomes appeared to be maintained concomittently with differences in the turnover rate and abundance of specific ribosomal proteins. Data are available via ProteomeXchange with identifier PXD012840. Significance Statement Protein synthesis is critical during abiotic stress, however we know little about the impact of oxidative stress on plant ribosomes. By tracking cytosolic ribosome abundance, turnover, and function, we show the robust maintenance of ribosome function, even when cell growth is significantly slowed, and discover selective patterns of ribosome subunit maintenance in plant cells.