The identification of the tRNA substrates for the<u>supK</u>tRNA methylase

Pope, William T.; Brown, Anne; Reeves, Robert H.

doi:10.1093/nar/5.3.1041

Cited by 34 publications

(30 citation statements)

References 11 publications

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“…This particular problem has been solved by Pope in a different context [16]. We can summarise his results as follows.…”

Section: Bps Dyons In N = 2 Su (3) Yang-mills Theorymentioning

confidence: 94%

“…The BPS monopole moduli space for this case is given by R 3 × (R × M)/Z where M is Taub-NUT space [5,14]. The BPS spectrum is then determined by solving the Dirac equation on the Taub-NUT manifold twisted by the tri-holomorphic Killing vector field and we will be able to utilise the results of Pope who studied precisely the same operator in [16].…”

Section: Introductionmentioning

confidence: 99%

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Monopole dynamics and BPS dyons inN=2super-Yang-Mills theories

et al. 2000

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We determine the low energy dynamics of monopoles in pure N = 2 YangMills theories for points in the vacuum moduli space where the two Higgs fields are not aligned. The dynamics is governed by a supersymmetric quantum mechanics with potential terms and four real supercharges. The corresponding superalgebra contains a central charge but nevertheless supersymmetric states preserve all four supercharges. The central charge depends on the sign of the electric charges and consequently so does the BPS spectrum. We focus on the SU(3) case where certain BPS states are realised as zero-modes of a Dirac operator on Taub-NUT space twisted by the tri-holomorphic Killing vector field. We show that the BPS spectrum includes hypermultiplets that are consistent with the strong-and weak-coupling behaviour of the Seiberg-Witten theory.

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“…This particular problem has been solved by Pope in a different context [16]. We can summarise his results as follows.…”

Section: Bps Dyons In N = 2 Su (3) Yang-mills Theorymentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Monopole dynamics and BPS dyons inN=2super-Yang-Mills theories

et al. 2000

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“…For example, the coding specificity of a tRNA can be altered by a change in the anticodon, either by base substitution (for review, see refs. [4][5][6] or by loss ofa base modification (7)(8)(9). In addition to anticodon changes, nucleotide substitutions in other parts of a tRNA molecule can result in suppression by causing attachment of an incorrect amino acid (5,10).…”

Section: Methodsmentioning

confidence: 99%

“…How this change, distant from the anticodon, alters the codon response has not been completely resolved, but a consequent change in the tertiary structure of the molecule has been implicated (13)(14)(15). Other mutational studies (7)(8)(9)(16)(17)(18)(19) also have indicated the importance oftRNA conformation in determining the specificity of codon response.…”

Section: Methodsmentioning

confidence: 99%

Nucleotide insertion in the anticodon loop of a glycine transfer RNA causes missense suppression.

Prather¹,

Murgola²,

Mims³

1981

Proc. Natl. Acad. Sci. U.S.A.

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We have determined the nucleotide sequences of two unusual UGG-suppressing glycine tRNAs from Escherichia coli and, as a result, have discovered a new mechanism for the generation of missense suppressors. The suppressor tRNAs translate UGG but not UGA. Each arose as a consequence of spontaneous mutational alteration of glyT, the gene for the GGA/Greading glycine tRNA of E. coli In each mutant tRNA, the change in primary structure involved the insertion ofan adenylate residue on the 3' side of the anticodon and the loss ofa modification of the uridylate residue at the 5' end of the anticodon. A "shift" of the effective anticodon by one nucleotide in the 3' direction can account for the new coding specificity of these tRNAs.(19). Nevertheless, both mutant glyT tRNAs suppressed UGG mutations occurring at the same positions in trpA (19). The conversion of a GGA/G-reading glycine tRNA to a UGG-specific suppressor alters its recognition of two positions of the codon (first and third). But suppressors of this type occur frequently, suggesting that members of this class of UGG suppressor can arise from a single mutational event. We determined the nucleotide sequence ofboth of these tRNAs and discovered a new type of missense suppressor tRNA. MATERIALS AND METHODSThe original hypothesis oftranslational suppression of missense mutations (1-3) proposed the general nature of tRNA involvement. To date, a variety of specific molecular alterations have been found to result in tRNA-mediated suppression. For example, the coding specificity of a tRNA can be altered by a change in the anticodon, either by base substitution (for review, see refs. 4-6) or by loss ofa base modification (7-9). In addition to anticodon changes, nucleotide substitutions in other parts of a tRNA molecule can result in suppression by causing attachment of an incorrect amino acid (5, 10). Moreover, a particular anticodon change was found to alter a tRNA so that it accepts a new amino acid and reads a different codon (11). An especially interesting suppressor tRNA is a mutant form of tRNA rP that can translate the termination codon UGA and the tryptophan codon, UGG (12). This mutant tRNA retains the original anticodon, and its suppressor activity is due to a single base change in the dihydrouracil arm of the molecule. How this change, distant from the anticodon, alters the codon response has not been completely resolved, but a consequent change in the tertiary structure of the molecule has been implicated (13)(14)(15). Other mutational studies (7-9, 16-19) also have indicated the importance oftRNA conformation in determining the specificity of codon response.In a recent report, we described the isolation and initial characterization of translational suppressors of a UGG missense mutation in Eschertichia coli (20). Eleven UGG suppressors were shown by genetic mapping and reversed-phase column chromatography to have alterations in glyT, the structural gene for a species of glycine tRNA. Nine suppressed both UGA and UGG mutations. This result was expe...

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“…First, the supK strain of S. typhimurium has two properties: suppression of UGA and a low level of tRNA methyltransferase (10,11,13). To explain this phenomenon, we have suggested that the supK gene encodes RF2 and that its mutant form affects the expression of the methyltransferase (4a).…”

mentioning

confidence: 99%

Conditionally lethal and recessive UGA-suppressor mutations in the prfB gene encoding peptide chain release factor 2 of Escherichia coli

1988

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Strains carrying mutations in the priB gene encoding peptide chain release factor 2 of Escherichia coli were isolated. prfBl, prJB2, and prJB3 were selected as suppressor mutations of a lacZ (UGA) mutation at 37°C, one of which, prJB2, is temperature sensitive in growth. A prJB286 strain was selected as a conditionally lethal mutant which grows at 32 but not at 43°C and was shown to have UGA-suppressor activity. All the mutations are recessive UGA-suppressors. These data indicate that release factor 2 is essential to E. coli growth and that all mutants isolated here trigger suppression of the UGA codon.Translation termination requires participation of two peptide chain release factors at specific termination codons in Escherichia coli. Release factor 1 (RF1) catalyzes termination at UAA and UAG codons, and release factor 2 (RF2) catalyzes termination at UGA and UAA codons (16). The gene encoding RF1, prfA, has been cloned and mapped at 27 min on the E. coli genome, and mutations in prfA have been shown to cause suppression. of UAG and UAA nonsense codons (8,9,14,15,19 In our previous work we suggested that a supK mutation of Salmonella typhimurium, a recessive UGA-suppressor mutation which maps in the same region as prfB in E. coli, affects the S. typhimurium RF2 protein (4a). To test directly whether a mutation in the prfB gene creates a UGA-suppressor activity in E. coli, we attempted to isolate mutations in prfB of E. coli. This article reports the isolation and the characterization of four RF2 mutants and the demonstration that they suppress the UGA nonsense codon.Two rationales of selection were used to isolate RF2 mutations, One was, to directly select a suppressor mutation of a lacZ UGA allele (lacZ659), some of which may have a defect in the peptide chain releaging activity of RF2 at the UGA codon. The other was to isolate a temperature-sensitive (ts) mutant which grows at low temperatures but not at high temperatures, because RF2 function may be essential to E. coli growth. In both cases, localized mutagenesis was conducted by transduction with mutagenized P1 phages by selecting for a TnlO transposon (zgc::TnJO) located about 7 kilobase pairs downstream of the prfB gene (4a) (Fig. 1). In the first selection scheme, P1 phages grown on the wild-type strain C600 (prfB+) carrying the closely linked TnlO marker were treated with hydroxylamine as described * Corresponding author. previously (7) and used to infect E. coli LS653, which carries the lacZ659 (UGA) mutation (17). Tetracycline-resistant (Tetr) transductants were directly selected at 37°C on lactose-MacConkey plates (MLA plates) containing tetracycline (15 ,ug/ml). Five "red" colonies, which are due to the increased lacZ expression, were isolated among 104 Tetr "white" transductants. The parental strain LS653 also harbors a UGA mutation in leu. Four of the five red colonies grew on leucine-free minimal plates, suggesting that these four acquired a UGA-suppressor activity. Linkage of these mutations to TnJO was scored by P1 transduction from the mutan...

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The identification of the tRNA substrates for thesupKtRNA methylase

Cited by 34 publications

References 11 publications

Monopole dynamics and BPS dyons inN=2super-Yang-Mills theories

Monopole dynamics and BPS dyons inN=2super-Yang-Mills theories

Nucleotide insertion in the anticodon loop of a glycine transfer RNA causes missense suppression.

Conditionally lethal and recessive UGA-suppressor mutations in the prfB gene encoding peptide chain release factor 2 of Escherichia coli

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