scholarly journals Peptide elongation in rat kidney after cadmium administration

1980 ◽  
Vol 190 (3) ◽  
pp. 791-797 ◽  
Author(s):  
M J Kuliszewski ◽  
D M Nicholls
Keyword(s):  
Rat Kidney ◽  
Gel Filtration ◽  
Elongation Factor ◽  
Peptide Bond ◽  
Renal Tissue ◽  
Elongation Factors ◽  
Elongation Factor 2 ◽  
Peptide Elongation ◽  
Elongation Factor 1 ◽  
Trna Binding

Rats received two injections (each 2.6 mg/kg body wt.) of CdCl2, and the kidneys were removed 24 h later. Postmicrosomal supernatant fractions of the homogenized kidneys were used as a source of elongation factors 1 and 2 in assays for [14C]phenylalanyl-tRNA binding to ribosomes and for peptide-bond synthesis. After purification of these preparations by precipitation with (NH4)2SO4 and gel filtration on Sephadex G-200 and G-100, elongation factor 1 activity was significantly increased. A significant increase in the activity of purified elongation factor 2 was also found. The results are discussed in relation to the reported effects of CdCl2 and of HgCl2 on renal tissue.

scholarly journals The mode of action of Shiga toxin on peptide elongation of eukaryotic protein synthesis

1987 ◽  
Vol 244 (2) ◽  
pp. 287-294 ◽  
Author(s):  
T G Obrig ◽  
T P Moran ◽  
J E Brown
Keyword(s):  
Protein Synthesis ◽  
Complex Formation ◽  
Shiga Toxin ◽  
Mode Of Action ◽  
Elongation Factor ◽  
Shigella Dysenteriae ◽  
Gtpase Activity ◽  
Elongation Factor 2 ◽  
Peptide Elongation ◽  
Elongation Factor 1

The effect of Shiga toxin, from Shigella dysenteriae 1, on the component reactions of peptide elongation were investigated. Enzymic binding of [3H]phenylalanine-tRNA to reticulocyte ribosomes was inhibited by 50% at 7 nM toxin. Elongation factor 1 (eEF-1)-dependent GTPase activity was also inhibited. Both reactions were not restored by addition of excess eEF-1 protein. In contrast, toxin concentrations of 200 nM were required to inhibit by 50% the elongation factor 2 (eEF-2)-dependent translocation of aminoacyl-tRNA on ribosomes. Addition of excess eEF-2 restored translocation activity. The eEF-2-dependent GTPase activity was unaffected at toxin concentrations below 100 nM, and Shiga-toxin concentrations of up to 1,000 nM did not affect either GTP.eEF-2.ribosome complex-formation or peptidyltransferase activity. Thus Shiga toxin closely resembles alpha-sarcin in action, both being primary inhibitors of eEF-1-dependent reactions. In contrast, the 60 S ribosome inactivators ricin and phytolaccin are primary inhibitors of eEF-2-dependent reactions of peptide elongation.

scholarly journals Relationship between elongation factor 1- and elongation factor 2-dependent guanosine triphosphatase activities of ribosomes. Inhibition of both activities by ricin

1975 ◽  
Vol 148 (3) ◽  
pp. 447-451 ◽  
Author(s):  
S Sperti ◽  
L Montanaro ◽  
A Mattioli ◽  
G Testoni
Keyword(s):  
Ribosomal Subunit ◽  
Elongation Factor ◽  
Elongation Factors ◽  
Toxic Protein ◽  
Elongation Factor 2 ◽  
Guanosine Triphosphatase ◽  
Elongation Factor 1 ◽  
Ricin A

The elongation factor 1- and elongation factor 2-dependent GTPase (guanosine triphosphatase) activities of ribosomes are inhibited by ricin, a toxic protein known to inactivate the 60S ribosomal subunit. It is suggested that also in eukaryotic ribosomes a “GTPase site’, located on the larger subunit, is common to the two elongation factors.

scholarly journals Regeneration of renal proximal tubules after mercuric chloride injury is accompanied by increased binding of aminoacyl-transfer ribonucleic acid

1976 ◽  
Vol 160 (2) ◽  
pp. 357-365 ◽  
Author(s):  
D McEwen ◽  
K Ng
Keyword(s):  
Rat Kidney ◽  
Elongation Factor ◽  
Proximal Tubules ◽  
Supernatant Fraction ◽  
Kidney Cortex ◽  
Rat Kidney Cortex ◽  
Aminoacyl Transfer ◽  
Increased Activity ◽  
Elongation Factor 1 ◽  
Trna Binding

Homogenates of rat kidney cortex obtained 1,3 or 14 days after a single injection of HgCl2 were used to prepare the post-microsomal pH5 supernatant fraction. The activity of this fraction for peptide synthesis from [14C]phenylalanyl-tRNA was significantly increased at 1 and 3 days, at which time the proximal tubules are regenerating [Cuppage & Tate (1967) Am. J. Pathol. 51, 405-429]. This increased activity could not be attributed to a decreased inhibitory activity, but was due to an increased aminoacyl-tRNA binding, i.e. elongation-factor-1 activity, in the supernatant fraction.

scholarly journals Oxazolidinone Antibiotics Target the P Site on Escherichiacoli Ribosomes

2002 ◽  
Vol 46 (4) ◽  
pp. 1080-1085 ◽  
Author(s):  
Hiroyuki Aoki ◽  
Lizhu Ke ◽  
Susan M. Poppe ◽  
Toni J. Poel ◽  
Elizabeth A. Weaver ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Wide Spectrum ◽  
Anaerobic Bacteria ◽  
Elongation Factor ◽  
Peptide Bond ◽  
23S Rrna ◽  
Peptide Bonds ◽  
A Site ◽  
Domain V ◽  
Trna Binding

ABSTRACT The oxazolidinones are a novel class of antimicrobial agents that target protein synthesis in a wide spectrum of gram-positive and anaerobic bacteria. The oxazolidinone PNU-100766 (linezolid) inhibits the binding of fMet-tRNA to 70S ribosomes. Mutations to oxazolidinone resistance in Halobacterium halobium, Staphylococcus aureus, and Escherichia coli map at or near domain V of the 23S rRNA, suggesting that the oxazolidinones may target the peptidyl transferase region responsible for binding fMet-tRNA. This study demonstrates that the potency of oxazolidinones corresponds to increased inhibition of fMet-tRNA binding. The inhibition of fMet-tRNA binding is competitive with respect to the fMet-tRNA concentration, suggesting that the P site is affected. The fMet-tRNA reacts with puromycin to form peptide bonds in the presence of elongation factor P (EF-P), which is needed for optimum specificity and efficiency of peptide bond synthesis. Oxazolidinone inhibition of the P site was evaluated by first binding fMet-tRNA to the A site, followed by translocation to the P site with EF-G. All three of the oxazolidinones used in this study inhibited translocation of fMet-tRNA. We propose that the oxazolidinones target the ribosomal P site and pleiotropically affect fMet-tRNA binding, EF-P stimulated synthesis of peptide bonds, and, most markedly, EF-G-mediated translocation of fMet-tRNA into the P site.

scholarly journals CTP can replace GTP in reactions catalyzed by eukaryotic peptide elongation factor 1

FEBS Letters ◽  
1984 ◽  
Vol 177 (1) ◽  
pp. 112-114 ◽  
Author(s):  
Z. Tuháčková ◽  
M. Havránek ◽  
J. Hradec
Keyword(s):  
Elongation Factor ◽  
Peptide Elongation ◽  
Elongation Factor 1

scholarly journals Decreased activity of peptide-elongation factors after treatment with cholesterol esterase

1978 ◽  
Vol 172 (1) ◽  
pp. 9-13 ◽  
Author(s):  
J Hradec ◽  
Z Tuháčková ◽  
Z Dušek
Keyword(s):  
Phospholipase A2 ◽  
Elongation Factor ◽  
Normal Activity ◽  
Normal Function ◽  
Cholesterol Esterase ◽  
Elongation Factors ◽  
Ribosomal Subunits ◽  
Binding Factor ◽  
Peptide Elongation ◽  
Sepharose 4B

1. Peptide-elongation factors were purified from rat liver and treated with cholesterol esterase and phospholipase A2 immobilized on Sepharose 4B. 2. Binding of L-[3H]-phenylalanyl-tRNA to 40S ribosomal subunits was decreased by approx. 70% and to polyribosomes by 30% in the presence of the binding factor incubated with cholesterol esterase. Treatment of this factor with immobilized phospholipase A2 decreased the binding to smaller ribosomal subunits by only about 15%. 3. Poly(U)-dependent phenylalanine polymerization by ribosomal subunits was decreased to approx. 30% of its original value by treatment of both elongation factors with cholesterol esterase. 4. The normal activity of esterase-treated elongation factor in both the binding reaction and peptide-elongation assay was fully recovered by the addition of cholesteryl 14-methyl-hexadecanoate. 5. Different classes of lipids present in peptide-elongation factor 1 have apparently different functions. Whereas phospholipids are required to maintain the strcture of heavy aggregates of this factor, the presence of cholesteryl 14-methylhexadecanoate is obviously necessary for the normal function of peptide-elongation factors.

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