scholarly journals The stability of mRNA for eucaryotic elongation factor Tu in Friend erythroleukemia cells varies with growth rate.

1988 ◽  
Vol 8 (3) ◽  
pp. 1085-1092 ◽  
Author(s):  
T R Rao ◽  
L I Slobin
Keyword(s):  
Stationary Phase ◽  
Mrna Decay ◽  
Elongation Factor ◽  
Growth Conditions ◽  
Decay Rates ◽  
Fresh Medium ◽  
Initiation Factor ◽  
Elongation Factor Tu ◽  
Messenger Ribonucleoprotein ◽  
The Stability

The decay rates of eucaryotic elongation factor Tu (eEF-Tu) mRNA and eucaryotic initiation factor 4A (eIF-4A) mRNA in Friend erythroleukemia (FEL) cells were determined under several different growth conditions. In FEL cells which were no longer actively dividing (stationary phase), eEF-Tu mRNA was found to be rather stable, with a t1/2 of about 24 h. In rapidly growing FEL cells eEF-Tu mRNA was considerably less stable, with a t1/2 of about 9 h. In both cases a single rate of mRNA decay was observed. However, when stationary-phase cells resumed growth after treatment with fresh medium, we observed that eEF-Tu mRNA decay followed a biphasic process. The faster of the two decay rates involved approximately 50% of the eEF-Tu mRNA and had a t1/2 of about 1 h. The decay rates for eIF-4A (t1/2 = 2 h) and total poly(A)+ RNA (t1/2 = 3 h) were unaffected by changes in growth conditions. The t1/2 for polysomal eEF-Tu mRNA was found to be about 8 h when stationary FEL cells were treated with fresh medium. Previous work in this laboratory has shown (T. R. Rao and L. I. Slobin, Mol. Cell. Biol. 7:687-697, 1987) that when FEL cells are allowed to grow to stationary phase, approximately 60% of the mRNA for eEF-Tu is found in a nontranslating postpolysomal messenger ribonucleoprotein (mRNP) particle. eEF-Tu mRNP was rapidly cleared from stationary cells after treatment with fresh medium. The data presented in this report indicate that the stability of eEF-Tu mRNP is rapidly altered and the particle is targeted for degradation when stationary FEL cells resume growth.

The stability of mRNA for eucaryotic elongation factor Tu in Friend erythroleukemia cells varies with growth rate

1988 ◽  
Vol 8 (3) ◽  
pp. 1085-1092
Author(s):  
T R Rao ◽  
L I Slobin
Keyword(s):  
Stationary Phase ◽  
Mrna Decay ◽  
Elongation Factor ◽  
Growth Conditions ◽  
Decay Rates ◽  
Fresh Medium ◽  
Initiation Factor ◽  
Elongation Factor Tu ◽  
Messenger Ribonucleoprotein ◽  
The Stability

The decay rates of eucaryotic elongation factor Tu (eEF-Tu) mRNA and eucaryotic initiation factor 4A (eIF-4A) mRNA in Friend erythroleukemia (FEL) cells were determined under several different growth conditions. In FEL cells which were no longer actively dividing (stationary phase), eEF-Tu mRNA was found to be rather stable, with a t1/2 of about 24 h. In rapidly growing FEL cells eEF-Tu mRNA was considerably less stable, with a t1/2 of about 9 h. In both cases a single rate of mRNA decay was observed. However, when stationary-phase cells resumed growth after treatment with fresh medium, we observed that eEF-Tu mRNA decay followed a biphasic process. The faster of the two decay rates involved approximately 50% of the eEF-Tu mRNA and had a t1/2 of about 1 h. The decay rates for eIF-4A (t1/2 = 2 h) and total poly(A)+ RNA (t1/2 = 3 h) were unaffected by changes in growth conditions. The t1/2 for polysomal eEF-Tu mRNA was found to be about 8 h when stationary FEL cells were treated with fresh medium. Previous work in this laboratory has shown (T. R. Rao and L. I. Slobin, Mol. Cell. Biol. 7:687-697, 1987) that when FEL cells are allowed to grow to stationary phase, approximately 60% of the mRNA for eEF-Tu is found in a nontranslating postpolysomal messenger ribonucleoprotein (mRNP) particle. eEF-Tu mRNP was rapidly cleared from stationary cells after treatment with fresh medium. The data presented in this report indicate that the stability of eEF-Tu mRNP is rapidly altered and the particle is targeted for degradation when stationary FEL cells resume growth.

Regulation of the utilization of mRNA for eucaryotic elongation factor Tu in Friend erythroleukemia cells

1987 ◽  
Vol 7 (2) ◽  
pp. 687-697
Author(s):  
T R Rao ◽  
L I Slobin
Keyword(s):  
Stationary Phase ◽  
Elongation Factor ◽  
Fold Increase ◽  
Growth Conditions ◽  
Fresh Medium ◽  
Initiation Factor ◽  
Elongation Factor Tu ◽  
Erythroleukemia Cells ◽  
Friend Erythroleukemia Cells

When Friend erythroleukemia cells were allowed to grow to stationary phase (2 X 10(6) to 3 X 10(6) cells per ml), approximately 60% of the mRNA for eucaryotic elongation factor Tu (eEF-Tu) sedimented at less than or equal to 80S, and most of the remaining factor mRNA was associated with small polysomes. Under the same growth conditions, greater than 90% of the mRNA for eucaryotic initiation factor 4A remained associated with polysomes. The association of eEF-Tu mRNA with polysomes changed dramatically when stationary-phase cells were treated with fresh medium. After 1 h in fresh medium, approximately 90% of eEF-Tu mRNA in Friend cells was found in heavy polysomes. Associated with the shift of eEF-Tu mRNA into heavy polysomes, we found at least a 2.6-fold increase in the synthesis of eEF-Tu in vivo as well as a remarkable 40% decrease in the total amount of eEF-Tu mRNA per cell. Our data raise the possibility that eEF-Tu mRNA that has accumulated in ribonucleoprotein particles in stationary-phase cells is degraded rather than reutilized for eEF-Tu synthesis.

scholarly journals Regulation of the utilization of mRNA for eucaryotic elongation factor Tu in Friend erythroleukemia cells.

1987 ◽  
Vol 7 (2) ◽  
pp. 687-697 ◽  
Author(s):  
T R Rao ◽  
L I Slobin
Keyword(s):  
Stationary Phase ◽  
Elongation Factor ◽  
Fold Increase ◽  
Growth Conditions ◽  
Fresh Medium ◽  
Initiation Factor ◽  
Elongation Factor Tu ◽  
Erythroleukemia Cells ◽  
Friend Erythroleukemia Cells

When Friend erythroleukemia cells were allowed to grow to stationary phase (2 X 10(6) to 3 X 10(6) cells per ml), approximately 60% of the mRNA for eucaryotic elongation factor Tu (eEF-Tu) sedimented at less than or equal to 80S, and most of the remaining factor mRNA was associated with small polysomes. Under the same growth conditions, greater than 90% of the mRNA for eucaryotic initiation factor 4A remained associated with polysomes. The association of eEF-Tu mRNA with polysomes changed dramatically when stationary-phase cells were treated with fresh medium. After 1 h in fresh medium, approximately 90% of eEF-Tu mRNA in Friend cells was found in heavy polysomes. Associated with the shift of eEF-Tu mRNA into heavy polysomes, we found at least a 2.6-fold increase in the synthesis of eEF-Tu in vivo as well as a remarkable 40% decrease in the total amount of eEF-Tu mRNA per cell. Our data raise the possibility that eEF-Tu mRNA that has accumulated in ribonucleoprotein particles in stationary-phase cells is degraded rather than reutilized for eEF-Tu synthesis.

Eukaryotic initiation factor 5A dephosphorylation is required for translational arrest in stationary phase cells

2013 ◽  
Vol 451 (2) ◽  
pp. 257-267 ◽  
Author(s):  
Janete Chung ◽  
Antonio A. Rocha ◽  
Renata R. Tonelli ◽  
Beatriz A. Castilho ◽  
Sergio Schenkman
Keyword(s):  
Protein Synthesis ◽  
Stationary Phase ◽  
Phosphorylation Site ◽  
Elongation Factor ◽  
Growth Conditions ◽  
Initiation Factor ◽  
Eukaryotic Initiation Factor ◽  
Wild Type ◽  
Translational Arrest ◽  
Aspartate Residue

The protein known as eIF5A (eukaryotic initiation factor 5A) has an elusive role in translation. It has a unique and essential hypusine modification at a conserved lysine residue in most eukaryotes. In addition, this protein is modified by phosphorylation with unknown functions. In the present study we show that a phosphorylated state of eIF5A predominates in exponentially growing Trypanosoma cruzi cells, and extensive dephosphorylation occurs in cells in stationary phase. Phosphorylation occurs mainly at Ser2, as shown in yeast eIF5A. In addition, a novel phosphorylation site was identified at Tyr21. In exponential cells, T. cruzi eIF5A is partially associated with polysomes, compatible with a proposed function as an elongation factor, and becomes relatively enriched in polysomal fractions in stationary phase. Overexpression of the wild-type eIF5A, or eIF5A with Ser2 replaced by an aspartate residue, but not by alanine, increases the rate of cell proliferation and protein synthesis. However, the presence of an aspartate residue instead of Ser2 is toxic for cells reaching the stationary phase, which show a less-pronounced protein synthesis arrest and a decreased amount of eIF5A in dense fractions of sucrose gradients. We conclude that eIF5A phosphorylation and dephosphorylation cycles regulate translation according to the growth conditions.

scholarly journals Elongation Factor Tu3 (EF-Tu3) from the Kirromycin Producer Streptomyces ramocissimus Is Resistant to Three Classes of EF-Tu-Specific Inhibitors

2007 ◽  
Vol 189 (9) ◽  
pp. 3581-3590 ◽  
Author(s):  
Lian N. Olsthoorn-Tieleman ◽  
Robert-Jan T. S. Palstra ◽  
Gilles P. van Wezel ◽  
Mervyn J. Bibb ◽  
Cornelis W. A. Pleij
Keyword(s):  
Protein Synthesis ◽  
Stationary Phase ◽  
Streptomyces Coelicolor ◽  
Elongation Factor ◽  
Elongation Factor Tu ◽  
Multiple Antibiotic Resistance ◽  
Prokaryotic Protein ◽  
Specific Inhibitors ◽  
Intrinsic Feature

ABSTRACT The antibiotic kirromycin inhibits prokaryotic protein synthesis by immobilizing elongation factor Tu (EF-Tu) on the elongating ribosome. Streptomyces ramocissimus, the producer of kirromycin, contains three tuf genes. While tuf1 and tuf2 encode kirromycin-sensitive EF-Tu species, the function of tuf3 is unknown. Here we demonstrate that EF-Tu3, in contrast to EF-Tu1 and EF-Tu2, is resistant to three classes of EF-Tu-targeted antibiotics: kirromycin, pulvomycin, and GE2270A. A mixture of EF-Tu1 and EF-Tu3 was sensitive to kirromycin and resistant to GE2270A, in agreement with the described modes of action of these antibiotics. Transcription of tuf3 was observed during exponential growth and ceased upon entry into stationary phase and therefore did not correlate with the appearance of kirromycin in stationary phase; thus, it is unlikely that EF-Tu3 functions as a resistant alternative for EF-Tu1. EF-Tu3 from Streptomyces coelicolor A3(2) was also resistant to kirromycin and GE2270A, suggesting that multiple antibiotic resistance is an intrinsic feature of EF-Tu3 species. The GE2270A-resistant character of EF-Tu3 demonstrated that this divergent elongation factor is capable of substituting for EF-Tu1 in vivo.

scholarly journals Molecular Effects of Elongation Factor Ts and Trigger Factor on the Unfolding and Aggregation of Elongation Factor Tu Induced by the Prokaryotic Molecular Chaperone Hsp33

Biology ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1171
Author(s):  
Minho Keum ◽  
Dai Ito ◽  
Mi-Seong Kim ◽  
Yuxi Lin ◽  
Kyeong-Hyeon Yoon ◽  
...  
Keyword(s):  
Molecular Chaperones ◽  
Protein Biosynthesis ◽  
Gel Filtration ◽  
Elongation Factor ◽  
Substantial Effect ◽  
Trigger Factor ◽  
Titration Calorimetry ◽  
Elongation Factor Tu ◽  
Regulate Protein ◽  
The Stability

Hsp33, a prokaryotic redox-regulated holding chaperone, has been recently identified to be able to exhibit an unfoldase and aggregase activity against elongation factor Tu (EF-Tu) in its reduced state. In this study, we investigated the effect of elongation factor Ts (EF-Ts) and trigger factor (TF) on Hsp33-mediated EF-Tu unfolding and aggregation using gel filtration, light scattering, circular dichroism, and isothermal titration calorimetry. We found that EF-Tu unfolding and subsequent aggregation induced by Hsp33 were evident even in its complex state with EF-Ts, which enhanced EF-Tu stability. In addition, although TF alone had no substantial effect on the stability of EF-Tu, it markedly amplified the Hsp33-mediated EF-Tu unfolding and aggregation. Collectively, the present results constitute the first example of synergistic unfoldase/aggregase activity of molecular chaperones and suggest that the stability of EF-Tu is modulated by a sophisticated network of molecular chaperones to regulate protein biosynthesis in cells under stress conditions.

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