Mathematical modelling of photoinhibition and Photosystem II repair cycle. I. Photoinhibition and D1 protein degradation in vitro and in the absence of chloroplast protein synthesis in vivo

1994 ◽  
Vol 41 (3) ◽  
pp. 439-449 ◽  
Author(s):  
Esa Tyystjärvi ◽  
Pirkko Mäenpää ◽  
Eva-Mari Aro
Keyword(s):  
Protein Synthesis ◽  
Photosystem Ii ◽  
Mathematical Modelling ◽  
Protein Degradation ◽  
D1 Protein ◽  
Photosystem Ii Repair ◽  
Repair Cycle ◽  
Chloroplast Protein Synthesis

Processing of the precursor to a chloroplast ribosomal protein made in the cytosol occurs in two steps, one of which depends on a protein made in the chloroplast

1985 ◽  
Vol 5 (5) ◽  
pp. 1093-1099
Author(s):  
R J Schmidt ◽  
N W Gillham ◽  
J E Boynton
Keyword(s):  
Molecular Weight ◽  
Protein Synthesis ◽  
Ribosomal Protein ◽  
Apparent Molecular Weight ◽  
Protein L ◽  
Mature Form ◽  
Chloroplast Protein Synthesis ◽  
Made In

In pulse-chase experiments in which log-phase cells of Chlamydomonas reinhardtii were labeled in vivo for 5 min with H2(35)SO4, fluorographs of immunoprecipitates from whole cell extracts revealed that chloroplast ribosomal proteins L-2, L-6, L-21, and L-29, which are made in the cytosol and imported, appeared in their mature forms. However, in the case of chloroplast ribosomal protein L-18, which is also made in the cytoplasm and imported, a prominent precursor with an apparent molecular weight of 17,000 was found at the end of a 5-min pulse. This precursor was processed to its mature size (apparent molecular weight of 15,500) within the first 5 min of the subsequent chase. As determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the precursor to L-18 formed in vivo was 1.5 kilodaltons smaller than the primary product detected in translations of Chlamydomonas polyadenylated RNA in vitro. Upon a 10-min incubation with a postribosomal supernatant from Chlamydomonas, the 18,500-dalton precursor detected in vitro could be partially converted into a polypeptide that comigrated with the 17,000-dalton precursor detected in extracts of cells labeled in vivo. Under conditions in which the total amounts of chloroplast proteins had been reduced and cells were made to synthesize ribosomes rapidly, the apparent half-life of the 17,000-dalton precursor was extended over that seen in log-phase cells. When chloroplast protein synthesis was inhibited with lincomycin for 3 h before labeling under these conditions, the 17,000-dalton L-18 precursor but not the mature form was found, and the precursor was slowly degraded during a 60-min chase. When cells were placed in the dark for 3 h before labeling, processing of this precursor to the mature form appeared unaffected, but the chloroplast-synthesized ribosomal protein L-26 was detected, indicating that chloroplast protein synthesis was still occurring. We interpret these results to indicate that the maturation of protein L-18 in vivo involves at least two processing steps, one of which depends on a protein made on chloroplast ribosomes.

scholarly journals Processing of the precursor to a chloroplast ribosomal protein made in the cytosol occurs in two steps, one of which depends on a protein made in the chloroplast.

1985 ◽  
Vol 5 (5) ◽  
pp. 1093-1099 ◽  
Author(s):  
R J Schmidt ◽  
N W Gillham ◽  
J E Boynton
Keyword(s):  
Molecular Weight ◽  
Protein Synthesis ◽  
Ribosomal Protein ◽  
Apparent Molecular Weight ◽  
Protein L ◽  
Mature Form ◽  
Chloroplast Protein Synthesis ◽  
Made In

In pulse-chase experiments in which log-phase cells of Chlamydomonas reinhardtii were labeled in vivo for 5 min with H2(35)SO4, fluorographs of immunoprecipitates from whole cell extracts revealed that chloroplast ribosomal proteins L-2, L-6, L-21, and L-29, which are made in the cytosol and imported, appeared in their mature forms. However, in the case of chloroplast ribosomal protein L-18, which is also made in the cytoplasm and imported, a prominent precursor with an apparent molecular weight of 17,000 was found at the end of a 5-min pulse. This precursor was processed to its mature size (apparent molecular weight of 15,500) within the first 5 min of the subsequent chase. As determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the precursor to L-18 formed in vivo was 1.5 kilodaltons smaller than the primary product detected in translations of Chlamydomonas polyadenylated RNA in vitro. Upon a 10-min incubation with a postribosomal supernatant from Chlamydomonas, the 18,500-dalton precursor detected in vitro could be partially converted into a polypeptide that comigrated with the 17,000-dalton precursor detected in extracts of cells labeled in vivo. Under conditions in which the total amounts of chloroplast proteins had been reduced and cells were made to synthesize ribosomes rapidly, the apparent half-life of the 17,000-dalton precursor was extended over that seen in log-phase cells. When chloroplast protein synthesis was inhibited with lincomycin for 3 h before labeling under these conditions, the 17,000-dalton L-18 precursor but not the mature form was found, and the precursor was slowly degraded during a 60-min chase. When cells were placed in the dark for 3 h before labeling, processing of this precursor to the mature form appeared unaffected, but the chloroplast-synthesized ribosomal protein L-26 was detected, indicating that chloroplast protein synthesis was still occurring. We interpret these results to indicate that the maturation of protein L-18 in vivo involves at least two processing steps, one of which depends on a protein made on chloroplast ribosomes.

In vitro studies on light-induced inhibition of Photosystem II and D1-protein degradation at low temperatures

1990 ◽  
Vol 1019 (3) ◽  
pp. 269-275 ◽  
Author(s):  
Eva-Mari Aro ◽  
Torill Hundal ◽  
Inger Carlberg ◽  
Bertil Andersson
Keyword(s):  
Photosystem Ii ◽  
Protein Degradation ◽  
Low Temperatures ◽  
D1 Protein ◽  
In Vitro Studies

scholarly journals Rates of protein turnover in vivo and in vitro in ventricular muscle of hearts from fed and starved rats

1984 ◽  
Vol 222 (2) ◽  
pp. 395-400 ◽  
Author(s):  
V R Preedy ◽  
D M Smith ◽  
N F Kearney ◽  
P H Sugden
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Turnover ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Ventricular Muscle ◽  
Degradation Rates ◽  
Perfused Hearts

Starvation of 300 g rats for 3 days decreased ventricular-muscle total protein content and total RNA content by 15 and 22% respectively. Loss of body weight was about 15%. In glucose-perfused working rat hearts in vitro, 3 days of starvation inhibited rates of protein synthesis in ventricles by about 40-50% compared with fed controls. Although the RNA/protein ratio was decreased by about 10%, the major effect of starvation was to decrease the efficiency of protein synthesis (rate of protein synthesis relative to RNA). Insulin stimulated protein synthesis in ventricles of perfused hearts from fed rats by increasing the efficiency of protein synthesis. In vivo, protein-synthesis rates and efficiencies in ventricles from 3-day-starved rats were decreased by about 40% compared with fed controls. Protein-synthesis rates and efficiencies in ventricles from fed rats in vivo were similar to values in vitro when insulin was present in perfusates. In vivo, starvation increased the rate of protein degradation, but decreased it in the glucose-perfused heart in vitro. This contradiction can be rationalized when the effects of insulin are considered. Rates of protein degradation are similar in hearts of fed animals in vivo and in glucose/insulin-perfused hearts. Degradation rates are similar in hearts of starved animals in vivo and in hearts perfused with glucose alone. We conclude that the rates of protein turnover in the anterogradely perfused rat heart in vitro closely approximate to the rates in vivo in absolute terms, and that the effects of starvation in vivo are mirrored in vitro.

Regulation of D1-protein degradation during photoinhibition of photosystem II in vivo: Phosphorylation of the D1 protein in various plant groups

Planta ◽  
1995 ◽  
Vol 195 (3) ◽  
Author(s):  
Eevi Rintam�ki ◽  
Riitta Salo ◽  
Elina Lehtonen ◽  
Eva-Mari Aro
Keyword(s):  
Photosystem Ii ◽  
Protein Degradation ◽  
D1 Protein ◽  
Plant Groups

Akt promotes increased mammalian cell size by stimulating protein synthesis and inhibiting protein degradation

2003 ◽  
Vol 285 (5) ◽  
pp. E964-E972 ◽  
Author(s):  
Jesika Faridi ◽  
Janet Fawcett ◽  
Lihong Wang ◽  
Richard A. Roth
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Cell Size ◽  
Specific Inhibitor ◽  
Phosphatidylinositol 3 Kinase ◽  
Inhibiting Protein ◽  
Regulate Protein ◽  
Mcf 7

Expression of constitutively active Akt3 was found to increase the size of MCF-7 cells approximately twofold both in vitro and in vivo. A regulatable version of Akt1 (MER-Akt) was also found capable of inducing a twofold increase in the size of H4IIE rat hepatoma cells. Rapamycin, a specific inhibitor of mTOR function, was found to inhibit the Akt-induced increase in cell size by 70%, presumably via inhibition of the Akt-induced increase in protein synthesis. To determine whether Akt could be inhibiting protein degradation, thereby contributing to its ability to induce an increase in cell size, we conducted protein degradation experiments in the H4IIE cell line. Activation of MER-Akt was found to inhibit protein degradation to a degree comparable to insulin treatment. The effects of these two agents on protein degradation were not additive, thereby suggesting that they were acting on a similar pathway. An inhibitor of the phosphatidylinositol 3-kinase pathway, LY-294002, blocked both insulin- and Akt-induced inhibition of protein degradation, again consistent with the hypothesis that both agents were acting on the same pathway. In contrast, rapamycin did not block the ability of either agent to inhibit protein degradation. These results indicate that Akt increases cell size through both mTOR-dependent and -independent pathways and that the latter involves inhibition of protein degradation. These studies are also consistent with the hypothesis that insulin's ability to regulate protein degradation is to a large extent mediated via Akt.

scholarly journals Leptin and leucine synergistically regulate protein metabolism in C2C12 myotubes and mouse skeletal muscles

2012 ◽  
Vol 110 (2) ◽  
pp. 256-264 ◽  
Author(s):  
Xiangbing Mao ◽  
Xiangfang Zeng ◽  
Zhimin Huang ◽  
Junjun Wang ◽  
Shiyan Qiao
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Skeletal Muscles ◽  
Receptor Expression ◽  
C2c12 Myotubes ◽  
Leucine Supplementation ◽  
Regulate Protein

Leucine and leptin play important roles in regulating protein synthesis and degradation in skeletal muscles in vitro and in vivo. However, the objective of the present study was to determine whether leptin and leucine function synergistically in regulating protein metabolism of skeletal muscles. In the in vitro experiment, C2C12 myotubes were cultured for 2 h in the presence of 5 mm-leucine and/or 50 ng/ml of leptin. In the in vivo experiment, C57BL/6 and ob/ob mice were randomly assigned to be fed a non-purified diet supplemented with 3 % l-leucine or 2·04 % l-alanine (isonitrogenous control) for 14 d. Ob/ob mice were injected intraperitoneally with sterile PBS or recombinant mouse leptin (0·1 μg/g body weight) for 14 d. In C57BL/6 mice, dietary leucine supplementation increased (P< 0·05) plasma leptin, leptin receptor expression and protein synthesis in skeletal muscles, but reduced (P< 0·05) plasma urea and protein degradation in skeletal muscles. Dietary leucine supplementation and leptin injection increased the relative weight of the gastrocnemius and soleus muscles in ob/ob mice. Moreover, leucine and leptin treatments stimulated (P< 0·05) protein synthesis and inhibited (P< 0·05) protein degradation in C2C12 myotubes and skeletal muscles of ob/ob mice. There were interactions (P< 0·05) between the leucine and leptin treatments with regard to protein metabolism in C2C12 myotubes and soleus muscles of ob/ob mice but not in the gastrocnemius muscles of ob/ob mice. Collectively, these results suggest that leptin and leucine synergistically regulate protein metabolism in skeletal muscles both in vitro and in vivo.

Turnover of total proteins and ornithine aminotransferase during liver regeneration in rats

1980 ◽  
Vol 238 (1) ◽  
pp. E46-E52
Author(s):  
S. L. Augustine ◽  
R. W. Swick
Keyword(s):  
Amino Acids ◽  
Liver Regeneration ◽  
Protein Degradation ◽  
Partial Hepatectomy ◽  
Free Amino ◽  
Liver Protein ◽  
Ornithine Aminotransferase ◽  
Fractional Rate

The recovery of approximately 40% of the total liver protein during the first day after partial hepatectomy was shown to be due to the near cessation of protein breakdown rather than to an increase in protein synthesis. The decrease in degradation of total protein was less if rats were adrenalectomized or protein-depleted prior to partial hepatectomy. The effect of these treatments originally suggested that changes in free amino acid levels in liver might be related to the rate of protein degradation. However, no correlation was found between levels of total free amino acids and rates of breakdown. Measurements of individual amino acids during liver regeneration suggested that levels of free methionine and phenylalanine, amino acids that have been found to lower rates of protein degradation in vitro, are not correlated with rates of breakdown in vivo. The difference between the fractional rate of ornithine aminotransferase degradation (0.68/day and 0.28/day in sham-hepatectomized and partially hepatectomized rats, respectively) was sufficient to account for the higher level of this protein 3 days after surgery in the latter group.

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