scholarly journals Effect of the antibiotic purpuromycin on cell-free protein-synthesizing systems

1989 ◽  
Vol 259 (1) ◽  
pp. 307-310 ◽  
Author(s):  
F Rambelli ◽  
M Brigotti ◽  
M Zamboni ◽  
M Denaro ◽  
L Montanaro ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Elongation Factor ◽  
Eukaryotic Cell ◽  
Artemia Salina ◽  
Culture Broth ◽  
Gram Positive Bacteria ◽  
Reticulocyte Lysate ◽  
Directed System ◽  
Bacteria And Fungi ◽  
Ribosomal Binding Site

Purpuromycin, an antibiotic isolated from the culture broth of Actinoplanes ianthinogenes, which is very active against Gram-positive bacteria and fungi, inhibits protein synthesis in both prokaryotic and eukaryotic cell-free systems. The ID50 was 9 microM with the endogenous mRNA-directed rabbit reticulocyte lysate, 17 microM with a poly(U)-directed system from Escherichia coli and 69 microM with a poly(U)-directed system from Artemia salina cysts. Of the three steps of elongation, purpuromycin does not affect the peptidyl-transferase reaction, inhibits the elongation factor 1 (EF-1) dependent binding of phenylalanyl-tRNA and stimulates the GTP-dependent binding of EF-2. When protein synthesis is stopped by the addition of purpuromycin, the nascent peptide chains are found in the puromycin-reactive P site. The results suggest that the mechanism of action of purpuromycin is similar to that of fusidic acid. Both antibiotics would seem to produce a stable guanine nucleotide-ribosome-EF-2 complex which allows one round of translocation but prevents, because of a common or overlapping ribosomal binding site for the two elongation factors, the subsequent EF-1-dependent binding of aminoacyl-tRNA.

scholarly journals Inhibition of protein synthesis in vitro by crotins and ricin. Effect on the steps of peptide chain elongation

1976 ◽  
Vol 156 (1) ◽  
pp. 7-13 ◽  
Author(s):  
S Sperti ◽  
L Montanaro ◽  
A Mattioli ◽  
G Testoni ◽  
F Stirpe
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Elongation Factor ◽  
Artemia Salina ◽  
Chain Elongation ◽  
Gtp Hydrolysis ◽  
Elongation Factor 2 ◽  
The Individual ◽  
Liver Ribosomes

The effects of crotin I and crotin II on the partial reactions of polypeptide chain elongation were investigated and compared with the known effects of ricin. Crotin II was a more powerful inhibitor than crotin I, but no qualitative differences between the two crotins were found. Rat liver ribosomes, preincubated with crotins and washed through sucrose gradients, remained inactive in protein synthesis. Among the individual steps of elongation, the peptidyltransferase reaction was unaffected by crotins, but some of the reactions that involve the interaction of elongation factors 1 and 2 with ribosomes were modified. A strong inhibition of the binding of elongation factor 2 to ribosomes and a stimulation of the elongation factor2-dependent GTP hydrolysis were observed; this indicates the formation of a very unstable elongation factor 2-GDP-ribosome complex, which, however, allows a single round of translocation to take place in the presence ofelongation factor 2 and added GTP. The elongation factor 1-dependent GTP hydrolysis was inhibited by crotins, whereas the enzymic binding of aminoacyl-tRNA, to both rat liver and Artemia salina ribosomes, was scarcely affected. In a protein-synthesizing system the inhibition by crotins and by ricin leads to a block of the nascent peptides on the ribosomal aminoacyl-tRNA site, an effect consistent with inhibition at the level of translocation. The mechanism of action of crotins appears to be very similar to that of ricin.

scholarly journals Isolation, characterization and evaluation of antimicrobial and cytotoxic activity of estragole, obtained from the essential oil of croton zehntneri (euphorbiaceae)

2015 ◽  
Vol 87 (1) ◽  
pp. 173-182 ◽  
Author(s):  
THALLITA C.B. ANDRADE ◽  
SIDNEY G. DE LIMA ◽  
RIVELILSON M. FREITAS ◽  
MÁRCIO S. ROCHA ◽  
TOREQUL ISLAM ◽  
...  
Keyword(s):  
Essential Oil ◽  
Human Cancer ◽  
Artemia Salina ◽  
Human Cancer Cell Lines ◽  
Gram Positive Bacteria ◽  
Zones Of Inhibition ◽  
Bacteria And Fungi ◽  
Main Components ◽  
Lc50 And Lc90 ◽  
Mcf 7

Croton zehntneri (Euphorbiaceae) is a native aromatic plant from Northeast region of Brazil. The monoterpenoid estragole (ESL) has been isolated by classical chromatographic methods from the essential oil (EO) of C. zehnteneri leaves and characterized by GC-FID and GC-MS, its antimicrobial and cytotoxic potentials being assessed. The analysis of the EO enabled the identification of 100% of the integrated constituents, of which yield was about 1.8%. The main components identified were: eucalyptol, estragole (84.7%) and spathulenol. The dosage of 50 μg/disk of ESL presented fairly significant zones of inhibition against Gram-positive bacteria and fungi. The ESL presented toxicity against Artemia salina with LC50 and LC90 of 4,54 and 8,47 μg mL-1. However, in tumor inhibition assays (human cells), there were no rewarding inhibition in any of the human cancer cell lines (MCF-7, HEP-2 and NCI-H292).

scholarly journals Effect of α-sarcin and ribosome-inactivating proteins on the interaction of elongation factors with ribosomes

1989 ◽  
Vol 257 (3) ◽  
pp. 723-727 ◽  
Author(s):  
M Brigotti ◽  
F Rambelli ◽  
M Zamboni ◽  
L Montanaro ◽  
S Sperti
Keyword(s):  
Higher Plants ◽  
Ricinus Communis ◽  
Ribosomal Subunit ◽  
Elongation Factor ◽  
Artemia Salina ◽  
Elongation Factors ◽  
Ribosome Inactivating Proteins ◽  
Rabbit Reticulocyte Lysate System ◽  
Reticulocyte Lysate ◽  
Comparable Activity

alpha-Sarcin from Aspergillus giganteus and the ribosome-inactivating proteins (RIPs) from higher plants inactivate the 60 S ribosomal subunit. The former is an RNAase, whereas RIPs are N-glycosidases. The site of cleavage of RNA and that of N-glycosidic depurinization are at one nucleotide distance in 28 S rRNA [Endo & Tsurugi (1987) J. Biol. Chem. 262, 8128-8130]. The effect of alpha-sarcin and that of RIPs on the interaction of elongation factors with Artemia salina (brine shrimp) ribosomes have been investigated. alpha-Sarcin inhibits both the EF1 (elongation factor 1)-dependent binding of aminoacyl-tRNA and the GTP-dependent binding of EF2 (elongation factor 2) to ribosomes, whereas two of the RIPs tested, ricin from Ricinus communis (castor bean) and volkensin from Adenia volkensii (kilyambiti), inhibit only the latter reaction. EF2 protects ribosomes from inactivation by both alpha-sarcin and ricin. The EF1-binding site is affected only by alpha-sarcin. The sensitivity of this site to alpha-sarcin is increased by pretreatment of ribosomes with ricin. A. salina ribosomes were highly resistant to the third RIP tested, namely gelonin from Gelonium multiflorum. All four proteins tested have, however, a comparable activity on the rabbit reticulocyte-lysate system.

scholarly journals Inhibition of bacterial protein synthesis by elongation-factor-Tu-binding antibiotics MDL 62,879 and efrotomycin

1992 ◽  
Vol 283 (3) ◽  
pp. 649-652 ◽  
Author(s):  
P Landini ◽  
M Bandera ◽  
B P Goldstein ◽  
F Ripamonti ◽  
A Soffientini ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Elongation Factor ◽  
Elongation Factor Tu ◽  
Free Protein ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
Bacterial Protein Synthesis ◽  
Heterologous Cell ◽  
Cell Free Protein Synthesis ◽  
High Binding Affinity

MDL 62,879 (formerly GE 2270 A) is a novel antibiotic active against Gram-positive bacteria by inhibiting protein synthesis. MDL 62,879 is not active against Gram-negative bacteria, but inhibits cell-free protein synthesis in extracts from Escherichia coli, and shows a high binding affinity for its elongation factor Tu (EF-Tu). We prepared ribosomes and protein-synthesis elongation factors from three sources: E. coli, Bacillus subtilis, and a strain of B. subtilis selected for resistance to MDL 62,879 (strain G1674). Homologous and heterologous reconstituted systems were used to compare the effects of MDL 62,879 and of efrotomycin, an EF-Tu inhibitor of the kirromycin class, which is inactive against both B. subtilis and E. coli. We showed that in cell-free protein synthesis: (a) E. coli was sensitive to both MDL 62,879 and efrotomycin; (b) B. subtilis was sensitive to MDL 62,879, but not to efrotomycin; (c) B. subtilis G1674 was resistant to both antibiotics. In the E. coli system and in the system from wild-type B. subtilis, inhibition by MDL 62,879 was reversed upon addition of purified EF-Tu from B. subtilis G1674. This demonstrates that the antibiotic acts by inhibition of EF-Tu. In contrast, extracts from B. subtilis failed to restore activity in an efrotomycin-inhibited E. coli system. Dominance or resistance to MDL 62,879 and of sensitivity to efrotomycin in heterologous cell-free protein synthesis confirms that inhibition of EF-Tu by the two antibiotics is mediated by different mechanisms of action.

scholarly journals Effects of antibody to 5 S-RNA-binding protein on protein synthesis in Artemia salina ribosomes

1989 ◽  
Vol 259 (1) ◽  
pp. 277-281 ◽  
Author(s):  
N Kenmochi ◽  
Y Takahashi ◽  
N L Sato
Keyword(s):  
Protein Synthesis ◽  
Rna Binding ◽  
Rna Binding Protein ◽  
Elongation Factor ◽  
Artemia Salina ◽  
Globin Mrna ◽  
Ribosomal Subunits ◽  
Elongation Factor 2 ◽  
Subunit Interface

The effects of an affinity-purified polyclonal antibody to Artemia salina ribosomal protein L5 on protein synthesis in vitro were examined. The antibody interacted with 60 S subunits more strongly than with 80 S ribosomes, and inhibited reassociation of ribosomal subunits to some extent at 5 mM-Mg2+ but not at 10 mM. Polyphenylalanine synthesis in vitro at 10 mM-Mg2+ was significantly inhibited, especially when the antibody was first preincubated with 60 S subunits prior to the assay. The incorporation of amino acid directed by globin mRNA was inhibited only when the preincubation with 60 S subunits was carried out. On the other hand, no effect was detected on elongation factor 2- and 60 S subunit-dependent uncoupled GTPase activity. These results suggest that L5 is probably located at or near the subunit interface and may play an important role in protein synthesis.

Isolation and partial characterization of a protein synthesis inhibitor from brine shrimp embryos

1977 ◽  
Vol 55 (9) ◽  
pp. 965-974 ◽  
Author(s):  
A. H. Warner ◽  
V. Shridhar ◽  
F. J. Finamore
Keyword(s):  
Protein Synthesis ◽  
Translational Control ◽  
Brine Shrimp ◽  
Elongation Factor ◽  
Artemia Salina ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Elongation Step ◽  
Artemia Cysts ◽  
Inhibitor Of Protein Synthesis

Encysted embryos of the brine shrimp, Artemia salina, contain an inhibitor of protein synthesis that appears to be important in translational control. In cyst homogenates, the inhibitor appears to be partitioned almost equally between the cytosol and ribosome fractions and it has been purified from both fractions to near homogeneity. In a cell-free protein-synthesizing system derived from Artemia cysts, with poly(U) as messenger, the protein inhibits polyphenylalanine synthesis proportional to inhibitor concentration up to about 75% inhibition, and the primary site of action appears to be at the elongation step. The inhibitor activity is not altered by 50–150 mM KCl in the reaction mixture, but it is slightly more effective at 5 mM MgCl2 than at 10 mM MgCl2. The inhibitor is a heat-labile protein of 130 000 molecular weight and is devoid of hydrolase activity. Our data indicate that the inhibitor is not elongation factor EF-1 or EF-2, but we are studying the possibility that it may be a modified form of elongation factor EF-2.

scholarly journals Inhibition of protein synthesis in vitro by proteins from the seeds of Momordica charantia (bitter pear melon)

1980 ◽  
Vol 186 (2) ◽  
pp. 443-452 ◽  
Author(s):  
L Barbieri ◽  
M Zamboni ◽  
E Lorenzoni ◽  
L Montanaro ◽  
S Sperti ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Affinity Chromatography ◽  
Potent Inhibitor ◽  
Artemia Salina ◽  
Momordica Charantia ◽  
Molar Excess ◽  
Reticulocyte Lysate ◽  
Inhibitor Of Protein Synthesis ◽  
Sepharose 4B

1. A haemagglutinating lectin was purified from the seeds of Momordica charantia by affinity chromatography on Sepharose 4B and on acid-treated Sepharose 6B. It has mol.wt. 115 000 and consists of four subunits, of mol.wts. 30 500, 29 000, 28 500 and 27 000. 2. The lectin inhibits protein synthesis by a rabbit reticulocyte lysate with an ID50 (concentration giving 50% inhibition) of approx. 5 micrograms/ml. Protein synthesis by Yoshida ascites cells is partially inhibited by the lectin at a concentration of 100 micrograms/ml. 3. From the same seeds another protein was purified which has mol.wt. 23 000 and is a very potent inhibitor of protein synthesis in the lysate system, with an ID50 of 1.8 ng/ml. This inhibitor has no effect on protein synthesis by Yoshida cells, and has no haemagglutinating properties. 4. Artemia salina ribosomes preincubated with the lectin or with the inhibitor lose their capacity to perform protein synthesis. The proteins seem to act catalytically, since they inactivate a molar excess of ribosomes. 5. The lectin and the inhibitor are somewhat toxic to mice, the LD50 being 316 and 340 micrograms/100 g body wt. respectively.

scholarly journals A novel bis(pyrazolyl)methane compound as a potential agent against Gram-positive bacteria

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pedro Seguí ◽  
John J. Aguilera-Correa ◽  
Elena Domínguez-Jurado ◽  
Christian M. Sánchez-López ◽  
Ramón Pérez-Tanoira ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Inhibitory Effect ◽  
Eukaryotic Cell ◽  
Liver Carcinoma ◽  
Gram Positive ◽  
Minimal Inhibitory Concentrations ◽  
E Coli ◽  
Gram Positive Bacteria ◽  
Therapeutic Compounds ◽  
Toxic Concentrations

AbstractThis study was designed to propose alternative therapeutic compounds to fight against bacterial pathogens. Thus, a library of nitrogen-based compounds bis(triazolyl)methane (1T–7T) and bis(pyrazolyl)methane (1P–11P) was synthesised following previously reported methodologies and their antibacterial activity was tested using the collection strains of Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. Moreover, the novel compound 2P was fully characterized by IR, UV–Vis and NMR spectroscopy. To evaluate antibacterial activity, minimal inhibitory concentrations (MICs), minimal bactericidal concentrations (MBCs), minimum biofilm inhibitory concentrations (MBICs), and minimum biofilm eradication concentrations (MBECs) assays were carried out at different concentrations (2–2000 µg/mL). The MTT assay and Resazurin viability assays were performed in both human liver carcinoma HepG2 and human colorectal adenocarcinoma Caco-2 cell lines at 48 h. Of all the synthesised compounds, 2P had an inhibitory effect on Gram-positive strains, especially against S. aureus. The MIC and MBC of 2P were 62.5 and 2000 µg/mL against S. aureus, and 250 and 2000 µg/mL against E. faecalis, respectively. However, these values were > 2000 µg/mL against E. coli and P. aeruginosa. In addition, the MBICs and MBECs of 2P against S. aureus were 125 and > 2000 µg/mL, respectively, whereas these values were > 2000 µg/mL against E. faecalis, E. coli, and P. aeruginosa. On the other hand, concentrations up to 250 µg/mL of 2P were non-toxic doses for eukaryotic cell cultures. Thus, according to the obtained results, the 2P nitrogen-based compound showed a promising anti-Gram-positive effect (especially against S. aureus) both on planktonic state and biofilm, at non-toxic concentrations.

scholarly journals Plant antimicrobial peptides: structures, functions, and applications

2021 ◽  
Vol 62 (1) ◽  
Author(s):  
Junpeng Li ◽  
Shuping Hu ◽  
Wei Jian ◽  
Chengjian Xie ◽  
Xingyong Yang
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Peptides ◽  
Agricultural Production ◽  
Food Additives ◽  
Antimicrobial Activities ◽  
Gram Positive Bacteria ◽  
Potential Applications ◽  
Potential Applicability ◽  
Bacteria And Fungi ◽  
Positively Charged

AbstractAntimicrobial peptides (AMPs) are a class of short, usually positively charged polypeptides that exist in humans, animals, and plants. Considering the increasing number of drug-resistant pathogens, the antimicrobial activity of AMPs has attracted much attention. AMPs with broad-spectrum antimicrobial activity against many gram-positive bacteria, gram-negative bacteria, and fungi are an important defensive barrier against pathogens for many organisms. With continuing research, many other physiological functions of plant AMPs have been found in addition to their antimicrobial roles, such as regulating plant growth and development and treating many diseases with high efficacy. The potential applicability of plant AMPs in agricultural production, as food additives and disease treatments, has garnered much interest. This review focuses on the types of plant AMPs, their mechanisms of action, the parameters affecting the antimicrobial activities of AMPs, and their potential applications in agricultural production, the food industry, breeding industry, and medical field.

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