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At least 19 recordsLinked to original sources
PubMed1985

The mechanism of resistance to puromycin and to the puromycin-precursor O-demethyl-puromycin in Streptomyces alboniger.

Ribosomes from Streptomyces alboniger are sensitive in vitro to puromycin and, to a lesser extent, to the puromycin-precursor O-demethyl-puromycin. The puromycin-inactivating enzyme (puromycin N-acetyltransferase) from S. alboniger also N-acetylates O-demethyl-puromycin. This finding indicates that in certain antibiotic-producing organisms the antibiotic-inactivating enzymes may play a role in self-defence against toxic precursor molecules.

Acetylation↗
PubMed1973

Effect of puromycin analogues and other agents on peptidyl-puromycin synthesis on polyribosomes.

The incorporation of [(3)H]puromycin into nascent polypeptide chains of polyribosomes has proved to be a sensitive method of evaluating effects of inhibitors on peptide bond synthesis. Several analogues of puromycin were found to react with polyribosomes from both bacteria and rat liver. The K(m) for puromycin is 4 muM with bacterial polyribosomes; under the same conditions, the K(i) for psi-hydroxy-puromycin (6-dimethylamino-9-[3-(l-beta-phenyllactylamino)-3-deoxy-beta- d-ribofuranosyl] purine) is 240 muM and for a carbocyclic analogue of puromycin (6-dimethylamino-9- {R- [2R-hydroxy-3R- (p-methoxyphenyl-l-alanylamino)]-cyclopentyl}purine) is 1 muM. Both were found to be competitive inhibitors of puromycin. The K(m) for C-A-C-C-A(Phe) is 250 muM. In addition, the dissociation constant for C-A-C-C-A(Phe) binding to washed ribosomes was found to be 1 and 0.03 muM in the absence and presence, respectively, of 20% (vol/vol) ethanol. The results with these analogues lead to the following conclusions. Substitution of a hydroxyl group for the alpha-amino group of puromycin results in an active analogue with about one-sixtieth the affinity of puromycin in the reaction. Omission of the 5'-hydroxymethyl group or substitution of the furanosyl ring oxygen by a carbon atom in the carbocyclic analogue reduces its activity compared with puromycin only slightly. Additionally, the relatively high K(m) for C-A-C-C-A(Phe) as an acceptor compared with puromycin suggests the existence of a protective mechanism on polyribosomes, which prevents aminoacyl-transfer ribonucleic acid (tRNA) free in solution from stripping nascent chains from polyribosomes so that only aminoacyl-tRNA bound to ribosomes through the appropriate coding mechanism can form a peptide bond.

Animals↗
PubMed1985

Biosynthesis of puromycin by Streptomyces alboniger: characterization of puromycin N-acetyltransferase.

Puromycin N-acetyltransferase from Streptomyces alboniger inactivates puromycin by acetylating the amino position of its tyrosinyl moiety. This enzyme has been partially purified by column chromatography through DEAE-cellulose and Affigel Blue and characterized. It has an Mr of 23 000, as determined by gel filtration. In addition to puromycin, the enzyme N-acetylates O-demethylpuromycin, a toxic precursor of the antibiotic, and chryscandin, a puromycin analogue antibiotic. The Km values for puromycin and O-demethylpuromycin are 1.7 and 4.6 microM, respectively. The O-demethylpuromycin O-methyltransferase from S. alboniger, which apparently catalyzes the last step in the biosynthesis of puromycin [Rao, M. M., Rebello, P. F., & Pogell, B. M. (1969) J. Biol. Chem. 244, 112-118], also O-methylates N-acetyl-O-demethylpuromycin. The Km values of the methylating enzyme for O-demethylpuromycin and N-acetyl-O-demethylpuromycin are 260 and 2.3 microM, respectively. These findings suggest that O-demethylpuromycin, if present in S. alboniger, would be N-acetylated and then O-methylated to be converted into N-acetylpuromycin. It might even be possible that N-acetylation of the puromycin backbone takes place at an earlier precursor.

Acetylation↗
PubMed1985

Isolation and properties of a puromycin acetyltransferase from puromycin-producing Streptomyces alboniger.

Puromycin 2"-N-acetyltransferase was isolated from cell extracts of puromycin-producing Streptomyces alboniger KCC S-0309 by ammonium sulfate fractionation, heat treatment to eliminate contaminant proteins and chromatography on DEAE-Toyopearl 650S. After PAGE (polyacrylamide gel electrophoresis) of the final fraction, a single protein band corresponding to puromycin 2"-N-acetyltransferase was detected. The molecular weight of the enzyme determined by SDS-PAGE and Sephadex G-150 chromatography was about 21,000 and 85,000, respectively, suggesting that the enzyme consisted of four subunits. The isoelectric point and the optimum pH for reaction were 6.2 and 7.7, respectively. The Km values for puromycin and acetyl coenzyme A were 40 microM and 67 microM, respectively. The enzyme was thermostable up to 70 degrees C for 12 minutes. It was shown, by using an in vitro protein synthesizing system from a puromycin-susceptible organism S. flavotricini subsp. pseudochromogenes V-13-1, that the isolated puromycin 2"-N-acetyltransferase could protect polyphenylalanine synthesis from inhibition by puromycin.

Acetyltransferases↗
PubMed1975

Photoincorporation of puromycin and N-(ethyl-2-diazomalonyl)puromycin into Escherichia coli ribosomes.

[3H]Puromycin and N-(ethyl-2-diazomalonyl)[3H]puromycin are incorporated into E. coli ribosomes on irradiation at 253.7 nm. Both compounds incorporate into both protein and nucleic acid. Two-dimensional gel electrophoresis of ribosomal protein shows that L23 is the major protein labeled by puromycin. Although incorporation is clearly a complex process, evidence is presented that L23 is labeled via an affinity labeling process, thus placing L23 at the aminoacyl-tRNA receptor (A) site. N-(ethyl-2-diazomalonyl)puromycin is a ribosomal ligand, as shown by its inhibition of two ribosomal assays, but it is not a good puromycin analog, and it is unclear whether its incorporation, which proceeds via both carbene-dependent and carbene-independent processes, results from affinity labeling.

Azo Compounds↗
PubMed1971

The rate-limiting step of protein synthesis in vivo and in vitro and the distribution of growing peptides between the puromycin-labile and puromycin-non-labile sites on polyribosomes.

1. At 3 min after an intravenous injection of radioactive amino acids into the rat, the bulk of radioactivity associated with liver polyribosomes can be interpreted as growing peptides. 2. In an attempt to identify the rate-limiting step of protein synthesis in vivo and in vitro, use was made of the action of puromycin at 0 degrees C, in releasing growing peptides only from the donor site, to study the distribution of growing peptides between the donor and acceptor sites. 3. Evidence is presented that all growing peptides in a population of liver polyribosomes labelled in vivo are similarly distributed between the donor and acceptor sites, and that the proportion released by puromycin is not an artifact of methodology. 4. The proportion released by puromycin is about 50% for both liver and muscle polyribosomes labelled in vivo, suggesting that neither the availability nor binding of aminoacyl-tRNA nor peptide bond synthesis nor translocation can limit the rate of protein synthesis in vivo. Attempts to alter this by starvation, hypophysectomy, growth hormone, alloxan, insulin and partial hepatectomy were unsuccessful. 5. Growing peptides on liver polyribosomes labelled in a cell-free system in vitro or by incubating hemidiaphragms in vitro were largely in the donor site, suggesting that either the availability or binding of aminoacyl-tRNA, or peptide bond synthesis, must be rate limiting in vitro and that the rate-limiting step differs from that in vivo. 6. Neither in vivo nor in the hemidiaphragm system in vitro was a correlation found between the proportion of growing peptides in the donor site and changes in the rate of incorporation of radioactivity into protein. This could indicate that the intracellular concentration of amino acids or aminoacyl-tRNA limits the rate of protein synthesis and that the increased incorporation results from a rise to a higher but still suboptimum concentration.

Alloxan↗
PubMed1990

Renal purine efflux and xanthine oxidase activity during experimental nephrosis in rats: difference between puromycin aminonucleoside and adriamycin nephrosis.

1. The hypothesis was tested that the renal xanthine oxidase system provides a source of oxygen free radicals in puromycin aminonucleoside and adriamycin experimental nephrosis by generating uric acid from hypoxanthine and xanthine. 2. The concentrations in renal tissue of the putative intermediary products of puromycin aminonucleoside metabolism, hypoxanthine and xanthine, and of their precursors, adenosine and inosine, were lower in rats treated with puromycin aminonucleoside than in normal controls, whereas concentrations of the metabolites were normal after adriamycin intoxication. Their daily urinary excretion was lower in the 24 h after puromycin aminonucleoside administration compared with the baseline values and returned to near normal levels within 5 days. After adriamycin the 24 h urinary excretion of xanthine and uric acid was double the baseline levels (P less than 0.001). 3. When equimolar amounts of hypoxanthine were injected instead of puromycin aminonucleoside, the concentration of all bases increased slightly in renal tissue and their urinary efflux was double the baseline level: allantoin, uric acid, the unmodified nucleotide and xanthine were the most represented compounds in urine. 4. The enzymatic activities relative to xanthine oxidase (EC 1.1.3.22) and xanthine dehydrogenase (EC 1.1.1.204) in renal tissues were unchanged 1 day after puromycin aminonucleoside or hypoxanthine intoxication and only moderately increased in both groups at 13 days (the time of appearance of heavy proteinuria in the puromycin aminonucleoside-treated group). In contrast, xanthine oxidase and xanthine dehydrogenase activities were higher in adriamycin-treated rats at 1 and 15 days after the treatment (P less than 0.001). 5. Feeding rats with normoprotein diets containing tungsten induced a marked and constant decrease of renal xanthine oxidase and xanthine dehydrogenase activities to 20% of the baseline values in both puromycin aminonucleoside- and adriamycin-treated rats. Inhibition of renal xanthine oxidase and xanthine dehydrogenase activities by tungsten was associated with a marked reduction (P less than 0.001) of proteinuria in adriamycin-treated rats and the same occurred with allopurinol, a specific inhibitor of xanthine oxidase activity. In contrast, tungsten treatment did not reduce the proteinuria associated with puromycin aminonucleoside, which reached a maximum 13 days after puromycin aminonucleoside intoxication. Hypoxanthine-treated rats were normoproteinuric after 2 months of observation. 6. These data demonstrate an activation of renal xanthine oxidase and xanthine dehydrogenase after adriamycin intoxication which is relevant to the induction of proteinuria. They also argue against the involvement of the renal xanthine oxidase system as a source of free radicals in puromycin aminonucleoside nephrosis and suggest that the nucleotide cycle is not a normal route for puromycin aminonucleoside degradation.(ABSTRACT TRUNCATED AT 400 WORDS)

Allantoin↗
PubMed1987

The effect of dilazep on puromycin-induced rat renal mitochondrial dysfunction.

The effect of tetrahydro-1 H-1,4 (5H)-dipropanol bis(3,4,5-trimethoxybenzoate)hydrochloride monohydrate (dilazep, Comelian) on puromycin-induced rat renal damage was investigated. In vivo study: Rats were divided into 3 groups, the control group; untreated, the puromycin group; puromycin (150 mg/kg) was injected intraperitoneally once, the dilazep + puromycin group; puromycin (150 mg/kg) was injected 1 h after intraperitoneal dilazep injection (2 mg/kg), and dilazep (2 mg/kg) was injected every 12 h until the end of the experiment. In each group, 84 h after puromycin injection, kidneys were isolated and renal mitochondria were prepared. The endogenous phospholipase activity in kidney homogenate was determined by high performance liquid chromatography. The activities of three segments (NADH-cytochrome c reductase, succinate-cytochrome c reductase and cytochrome c oxidase) of the electron-transport chain in mitochondria were measured enzymatically. In the puromycin group, phospholipase activity was increased and activities of all of three segments of the electron-transport chain were decreased. In the dilazep + puromycin group, premedication with dilazep prevented activation of phospholipase and maintained mitochondrial electron-transport activity. In vitro study: Mitochondria prepared from intact rat kidney were incubated with phospholipase C. Activities of the mitochondrial electron-transport chain were deteriorated by phospholipase C. These results indicated that activation of endogenous phospholipase, which digests membrane phospholipids, essential components in maintaining mitochondrial electron-transport activity, is responsible for the puromycin-induced renal damage. Premedication with dilazep prevented the damage by inhibition of the activation of phospholipase.

Animals↗
PubMed1989

Stimulation by insulin of glycolysis in cultured hepatocytes is attenuated by extracellular ATP and puromycin through purine-dependent inhibition of phosphofructokinase 2 activation.

Activation of glycolysis by insulin in cultured rat hepatocytes is preceded by an activation of phosphofructokinase 2 (PFK 2) and subsequent rise of the fructose 2,6-bisphosphate [Fru(2,6)P2] level. Extracellular addition of ATP or puromycin prevented the hormonal effect on glycolysis. The mechanism through which the purines abolished glycolytic stimulation was investigated. 1. 50 microM ATP completely prevented the 3-5-fold insulin-dependent increase of glycolysis, irrespective of whether the cells initially possessed a low or a high Fru(2,6)P2 content. 50 microM puromycin prevented the stimulation of glycolysis by insulin only in cells whose initial Fru(2,6)P2 levels were low and had to be increased by insulin prior to the increase in glycolysis. It did not antagonize the action of insulin cells with initial high Fru(2,6)P2 content. 2. ATP exerted effects on its own; it decreased initially high Fru(2,6)P2 levels by 95% within 10 min and decreased the basal glycolytic rate by 60%. Half-maximal effects on the Fru(2,6)P2 level were obtained with about 25 microM ATP or 15 microM adenosine 5'[beta, gamma-methylene]triphosphate. ADP and adenosine-5-[gamma-thio]triphosphate were as effective as ATP, whereas 100 microM adenosine 5'[alpha, beta-methylene]triphosphate elicited no effect. Puromycin neither decreased high Fru(2,6)P2 levels nor inhibited basal glycolysis. 3. Extracellular ATP (100 microM) led to inhibition of the active form of PFK 2. Intracellular levels of Glc6P, citrate, ATP, ADP and AMP were increased by extracellular ATP, the phosphoenolpyruvate content was decreased, Fru6P and glycerol 3-phosphate levels stayed constant. Puromycin did not inhibit PFK 2. 4. Both puromycin and ATP prevented the insulin-dependent rise of the Fru(2,6)P2 level, they abolished the activation of PFK 2 by the hormone. Puromycin did not block the accumulation of Fru(2,6)P2 provoked by glucose addition; ATP also antagonized the glucose-dependent increase. 5. 100 microM ATP elevated the cAMP-dependent protein kinase activity ratio from 0.1 to 0.38 and increased the level of inositol trisphosphate by 16-fold within 5 min, whereas puromycin was without effect on either level. It is concluded that the two purines block the insulin effect on glycolysis by preventing the hormone increasing the Fru(2,6)P2 level. The mode of action, however, seems to be different: ATP antagonizes insulin action in that it leads to increased inhibition of PFK 2 whereas puromycin prevents the activation of PFK 2 by insulin.

Adenosine Triphosphate↗
PubMed1969

Memory in the Japanese quail: effects of puromycin and acetoxycycloheximide.

Intracerebral injections of puromycin produced memory deficits in naive quail trained to discriminate between red and green stimuli. Puromycin aminonucleoside, acetoxycycloheximide, and saline had no such effect. After a single reversal of the visual cues, naive quail treated with puromycin performed better than control birds. Also, puromycin had no effect on performance when injected into previously trained animals. High doses both of puromycin and acetoxycycloheximide inhibited ribonucleic acid and protein synthesis to a similar extent, while low doses of puromycin inhibited only protein synthesis. Since only puromycin inhibited memory, the basis for its effect appears more likely to be mediated by the action of peptidyl-puromycin rather than by the quantitative inhibition of macromolecular synthesis or by some nonspecific toxic action.

Animals↗
PubMed1978

Testing with puromycin and amino acyl tRNAs that limit the rate of peptide chain extension.

With puromycin one can recognize when the synthesis of a given protein is dependent on amino acyl tRNA that is present in rate limiting amount. We demonstrate this use of puromycin by its interaction with another inhibitor, L-o-methylthreonine. L-o-methylthreonine lowers the Ile-tRNA concentration in the cell, thereby inhibiting synthesis of proteins containing isoleucine. In certain rabbits, the alpha hemoglobin chain has three isoleucyl residues and the beta chain none. L-o-methylthreonine thus inhibits alpha globin synthesis in intact reticulocytes from these rabbits. When puromycin and L-o-methylthreonine are used together, the two inhibitors synergize in inhibiting alpha globin synthesis. Hence, puromycin is a more effective inhibitor when the Ile-tRNA concentration is lowered. Cycloheximide and sodium fluoride have different modes of action from puromycin. Neither synergizes with L-o-methylthreonine; instead, the interaction is less than additive. We have found that beta chain synthesis in rabbit reticulocytes is more sensitive than alpha to inhibition by puromycin. This difference could reflect either differences in amino acid sequence or tRNA dependent limitations of beta chain elongation. The switch from fetal to adult hemoglobin in humans does not involve changes in limiting amino acyl tRNA because, for cord blood from infants of different developmental ages, the puromycin sensitivity of incorporation into gamma and beta chains remains constant.

Animals↗
PubMed1992

Parthenogenetic activation of human oocytes by puromycin.

OBJECTIVE: Our objective was to obtain parthenogenetic activation of unfertilized human oocytes by puromycin and to try to use this procedure for cytogenetic purposes. SETTING: The setting was our IVF laboratory. METHODS: Eighty-two spare oocytes from 34 IVF patients were used. In the first series of experiments 39 unfertilized oocytes were cultured in medium containing 100, 50, or 10 micrograms/ml puromycin for 6 to 24 hr. After the appearance of pronuclei they were transferred to plain medium, further cultured, and cytogenetically analyzed. In the second series of experiments 43 oocytes were cultured for 5 to 10 hr in 10 micrograms/ml puromycin, transferred to plain medium, and fixed for cytogenetic analysis 2 hr after nuclear envelope breakdown. RESULTS: Ninety-one percent of the oocytes in the first experiment showed the presence of one or more nuclei. From the pronucleate oocytes additionally cultured in puromycin-free medium, 46% developed further to the metaphase of the first mitotic division or the two-cell stage and 54% remained arrested at the pronuclear stage. In the second experiment 88% of the treated oocytes showed pronuclei or had cleaved, and after withdrawal from puromycin 96% of the pronucleate oocytes entered mitosis. CONCLUSION: Puromycin induces haploid as well as diploid parthenogenesis in aged human oocytes. A 5- to 10-hr treatment of oocytes with 10 micrograms/ml puromycin yields the highest percentage of activation, and almost all parthenogenetically activated oocytes enter or develop beyond the first cleavage mitosis. Analysis of mitotic metaphase chromosomes from parthenogenetically activated human oocytes may be a promising new approach to preimplantation cytogenetics.

Cell Division↗