Bacterial senescence: protein oxidation in non-proliferating cells is dictated by the accuracy of the ribosomes.
We have investigated the causal factors behind the age-related oxidation of proteins during arrest of cell proliferation. A proteomic approach demonstrated that protein oxidation in non-proliferating cells is observed primarily for proteins being produced in a number of aberrant isoforms. Also, these cells exhibited a reduced translational fidelity as demonstrated by both proteomic analysis and genetic measurements of nonsense suppression. Mutants harboring hyperaccurate ribosomes exhibited a drastically attenuated protein oxidation during growth arrest. In contrast, oxidation was augmented in mutants with error-prone ribosomes. Oxidation increased concomitantly with a reduced rate of translation, indicating that the production of aberrant, and oxidized proteins, is not the result of titration of the co-translational folding machinery. The age-related accumulation of the chaperones, DnaK and GroEL, was drastically attenuated in the hyperaccurate rpsL mutant, demonstrating that the reduced translational fidelity in growth-arrested cells may also be a primary cause for the induction of the heat shock regulon. The data point to an alternative way of approaching the causal factors involved in protein oxidation in eukaryotic G(0) cells.
Ballesteros
M
M
Department of Cell and Molecular Biology-Microbiology, Göteborg University, Medicinaregatan 9C, 413 90 Göteborg, Sweden.
Fredriksson
A
A
Henriksson
J
J
Nyström
T
T
D001426:Bacterial Proteins / Q000378:metabolism*; D002455:Cell Division; D018834:Chaperonin 60 / Q000378:metabolism; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D005947:Glucose / Q000502:physiology; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010101:Oxygen Consumption; D010441:Peptide Chain Elongation, Translational; D014176:Protein Biosynthesis; D020033:Protein Isoforms / Q000096:biosynthesis; D020543:Proteome; D000091243:Ribosomal Protein S9; D012270:Ribosomes / Q000502:physiology*; D013997:Time Factors
D001426:Bacterial Proteins; D018834:Chaperonin 60; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D020033:Protein Isoforms; D020543:Proteome; D000091243:Ribosomal Protein S9; C000717190:RpsI protein, E coli; C063842:dnaK protein, E coli; D005947:Glucose