The Fidelity of Translation

Abraham, Abraham K.

doi:10.1016/s0079-6603(08)60084-7

Cited by 16 publications

(9 citation statements)

References 85 publications

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“…Many reports, using extracts derived from a number of cell types, indicate that, in the cell-free systems PAs stimulate a variety of processes of protein biosynthesis, such as stabilization and activation of tRNA (Cohen 1978), stimulation of initiation of translation (Konecki et al 1975), ensuring fidelity of translation (Abraham 1983), stimulation of the synthesis of specific proteins (Woese and Fox 1977;Lake et al 1984;Higgins 1995), and stimulation of in vitro reconstitution of ribosomal subunits (Kakegawa et al 1986a,b). In fact, ribosomes and tRNA isolated from a variety of eukaryotic and prokaryotic cells have been found to contain significant amounts of PAs (Stevens and Pascoe 1972;Cohen 1978).…”

Section: Discussionmentioning

confidence: 99%

Immunoelectron Microscopic Study for Polyamines

Fujiwara

Bai²,

Kitagawa³

et al. 1998

J Histochem Cytochem.

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SUMMARYThe polyamines (PAs) are ubiquitous polycationic metabolites in eukaryotic and prokaryotic cells and are believed to be intimately involved in the regulation of DNA, RNA, and protein biosynthesis, the exact function of which remains unclear, mainly because of a lack of knowledge of PA subcellular localization. In this study, using immunoelectron microscopy, we have demonstrated that PAs are predominantly located on free and attached ribosomes of the rough endoplasmic reticulum in the neurons of the lateral reticular nucleus of rat medulla oblongata. The nuclei, axons, and nerve endings were devoid of PA. This suggests that PAs are one of the components of biologically active ribosomes, being closely involved in the translation processes of protein biosynthesis.

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Section: Discussionmentioning

confidence: 99%

Immunoelectron Microscopic Study for Polyamines

Fujiwara

Bai²,

Kitagawa³

et al. 1998

J Histochem Cytochem.

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“…The nucleoside tetraphosphate ppGpp has been reported to enhance the fidelity of translation of proteins (Abraham, 1983;Yarus & Thompson, 1983;Dix & Thompson, 1986), and its effect on the production of catalytically active tryptophan synthase a protein was measured. When employed at concentrations up to 0.5 mM, ppGpp was found to have little effect on incorporation of [* 023 *5H]phenylalanine into protein or on the activity of tryptophan synthase activity of the a subunit as measured in the 02 complementation assay (supplementary material Figure 4).…”

Section: Resultsmentioning

confidence: 99%

“…Because previous studies have demonstrated that mRNA mistranslation in vitro can greatly exceed that which normally obtains in vivo [Jelenc and Kurland (1979) it seemed important to characterize the effects of parameters shown previously to affect the fidelity of protein biosynthesis on the activity of our synthetic tryptophan synthase a subunit. Polyamines have been reported to improve the fidelity of translation in vitro [Jelenc and Kurland (1979) and references cited therein; Igarashi et al, 1979;Abraham, 1983;Yarus & Thompson, 1983], and the effect of one polyamine on the coupled transcription-translation system utilized here was assayed directly. As illustrated in Figure 4, at each of three concentrations of Mg2+, the addition of spermidine at concentrations up to 5 mM had little effect on the extent of polypeptide synthesis, except where the concentration of Mg2+ was suboptimal.…”

Section: Discussionmentioning

confidence: 99%

Escherichia coli tryptophan synthase: synthesis of catalytically competent .alpha. subunit in a cell-free system containing preacylated tRNAs

Payne¹,

Nichols²,

Hecht³

1987

Biochemistry

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A cell-free protein biosynthesizing system prepared from Escherichia coli CF300 was found to synthesize E. coli tryptophan synthase alpha subunit in a time-dependent manner when programmed with pBN69 plasmid DNA. This plasmid contains the trp promoter from Serratia marcescens adjacent to the coding region of E. coli tryptophan synthase alpha protein [Nichols, B.P., & Yanofsky, C. (1983) Methods Enzymol. 101, 155-164]. The synthesized tryptophan synthase alpha subunit was found to be indistinguishable from authentic alpha subunit protein when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and to have the same specific activity for catalyzing the conversion of indole----L-tryptophan by tryptophan synthase beta 2 subunit, as well as the conversion of indole + glyceraldehyde 3-phosphate to indole-3-glycerol phosphate. In the absence of exogenously added phenylalanine, admixture of E. coli phenylalanyl-tRNAPhe to the protein biosynthesizing system stimulated the production of functional alpha protein; the analogous result was obtained when valine was replaced by E. coli valyl-tRNAVal. The ability of a misacylated tRNA to participate in alpha protein synthesis in this system was established by the use of E. coli phenylalanyl-tRNAVal in the absence of added valine. Protein biosynthesis proceeded normally and gave a product having the approximate molecular weight of tryptophan synthase alpha subunit; as expected, this polypeptide lacked catalytic activity.

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“…For most aminoacyl-tRNA synthetases, the extent of inaccuracy in i o is low while misactivation in systems in itro varies with the assay conditions [4]. If one assumes that the proofreading activity of Met-tRNA synthetase alone is respon-charged with ["%C]homocysteine, revealed radioactivity in homocysteine, methionine and homocysteine thiolactone, indicating a conversion of tRNA-attached homocysteine to methionine.…”

Section: Introductionmentioning

confidence: 99%

A novel pathway for the conversion of homocysteine to methionine in eukaryotes

Antonio

Nunes

Refsum

et al. 1997

Biochemical Journal

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Activation of amino acid homocysteine was compared with that of methionine in rabbit crude liver extracts and purified multi-enzyme complex of aminoacyl-tRNA synthetases. Activation was studied by measuring the incorporation of radioactive amino acid into unlabelled trichloroacetic-acid insoluble materials in the absence of protein synthesis. Homocysteine synthetase activity was found in the crude extract and in the purified multi-enzyme complex of aminoacyl-tRNA synthetases. On a molar basis, the activation of methionine by the crude extract was five times higher than the activation of homocysteine. There was a partial loss of Hcy-tRNA synthetase activity in the purified multi-enzyme complex. Preliminary reconstitution experiments indicated a requirement for an additional factor for Hcy-tRNA synthetase activity. TLC of the amino acid released from tRNA charged with [14C]homocysteine, revealed radioactivity in homocysteine, methionine and homocysteine thiolactone, indicating a conversion of tRNA-attached homocysteine to methionine. Total tRNA was separated on a benzoylated cellulose column into a fraction enriched in initiator tRNA and a methionine-accepting, but initiator tRNA-deficient, fraction. Homocysteine-accepting activity was present only in the initiator tRNA-enriched fraction. Based on the above data we propose that homocysteine activation in reticulocyte lysates, reported previously, also occurs in liver. Activated homocysteine is attached to initiator tRNA and then converted to methionine by a methylating enzyme. In the absence of methylation, tRNA-attached homocysteine is hydrolysed to produce homocysteine thiolactone.

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The Fidelity of Translation

Cited by 16 publications

References 85 publications

Immunoelectron Microscopic Study for Polyamines

Immunoelectron Microscopic Study for Polyamines

Escherichia coli tryptophan synthase: synthesis of catalytically competent .alpha. subunit in a cell-free system containing preacylated tRNAs

A novel pathway for the conversion of homocysteine to methionine in eukaryotes

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