title: Quantifying protein synthesis and degradation in Arabidopsis by dynamic 13CO2 labeling and analysis of enrichment in individual amino acids in their free pools and in protein.
abstract: Protein synthesis and degradation represent substantial costs during plant growth. To obtain a quantitative measure of the rate of protein synthesis and degradation, we supplied (13)CO2 to intact Arabidopsis (Arabidopsis thaliana) Columbia-0 plants and analyzed enrichment in free amino acids and in amino acid residues in protein during a 24-h pulse and 4-d chase. While many free amino acids labeled slowly and incompletely, alanine showed a rapid rise in enrichment in the pulse and a decrease in the chase. Enrichment in free alanine was used to correct enrichment in alanine residues in protein and calculate the rate of protein synthesis. The latter was compared with the relative growth rate to estimate the rate of protein degradation. The relative growth rate was estimated from sequential determination of fresh weight, sequential images of rosette area, and labeling of glucose in the cell wall. In an 8-h photoperiod, protein synthesis and cell wall synthesis were 3-fold faster in the day than at night, protein degradation was slow (3%-4% d(-1)), and flux to growth and degradation resulted in a protein half-life of 3.5 d. In the starchless phosphoglucomutase mutant at night, protein synthesis was further decreased and protein degradation increased, while cell wall synthesis was totally inhibited, quantitatively accounting for the inhibition of growth in this mutant. We also investigated the rates of protein synthesis and degradation during leaf development, during growth at high temperature, and compared synthesis rates of Rubisco large and small subunits of in the light and dark.
authors: Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany.
authors: Hirofumi
authors: http://orcid.org/0000-0002-7658-0473
authors: H
authors: Ishihara
authors: Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany.
authors: Toshihiro
authors: http://orcid.org/0000-0001-8931-7722
authors: T
authors: Obata
authors: Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany.
authors: Ronan
authors: http://orcid.org/0000-0002-6113-9570
authors: R
authors: Sulpice
authors: Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany.
authors: Alisdair R
authors: AR
authors: Fernie
authors: Max Planck Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany mstitt@mpimp-golm.mpg.de.
authors: Mark
authors: M
authors: Stitt
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes; D002467:Cell Nucleus / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D060146:Ecotype; D005947:Glucose / Q000378:metabolism; D007553:Isotope Labeling; D007700:Kinetics; D009154:Mutation; D010733:Phosphoglucomutase / Q000378:metabolism; D017440:Photoperiod; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism; D018087:Plastids / Q000378:metabolism; D014176:Protein Biosynthesis; D021122:Protein Subunits / Q000378:metabolism; D059748:Proteolysis; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D013213:Starch / Q000378:metabolism; D013696:Temperature
chemical_list: D000596:Amino Acids; D029681:Arabidopsis Proteins; D002247:Carbon Isotopes; D021122:Protein Subunits; D002245:Carbon Dioxide; D013213:Starch; D012273:Ribulose-Bisphosphate Carboxylase; D010733:Phosphoglucomutase; D005947:Glucose