On the recognition of serine transfer RNA's specific for unrelated codons by the same seryl-transfer RNA synthetase.

Sundharadas, G.; Katze, Jon R.; Söll, Dieter; Konigsberg, William H.; Lengyel, Péter

doi:10.1073/pnas.61.2.693

Cited by 40 publications

(13 citation statements)

References 9 publications

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“…Small differences in interaction of the mutant enzyme with the various isoacceptors would have gone undetected, but there seems to be no discrimination against a particular tRNA species by the mutant enzyme. The finding of the LeuRS and SerRS mutants provides genetic evidence for the existence of a single LeuRS and SerRS in E. coli, as suggested by biochemical studies (16,27,35).…”

Section: Resultssupporting

confidence: 53%

Isolation and Partial Characterization of Temperature-Sensitive Escherichia coli Mutants with Altered Leucyl- and Seryl-Transfer Ribonucleic Acid Synthetases

et al. 1971

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Two temperature-sensitive mutants of Escherichia coli have been found in which the conditional growth is a result of a thermosensitive leucyl-transfer ribonucleic acid (tRNA) synthetase and seryl-tRNA synthetase, respectively. The corresponding genetic loci, leuS and serS, cotransduce with lip and serC, respectively. As a result of the mutationally altered leucyl-tRNA synthetase, some leucine-, valine-, and isoleucine-forming enzymes were derepressed. Thus, leucyl-tRNA synthetase is involved in the repression of the enzymes needed for the synthesis of branched-chain amino acids.on July 16, 2020 by guest

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Section: Resultssupporting

confidence: 53%

Isolation and Partial Characterization of Temperature-Sensitive Escherichia coli Mutants with Altered Leucyl- and Seryl-Transfer Ribonucleic Acid Synthetases

et al. 1971

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“…This general notion was specifically contradicted by evidence on suppressor tRNA (3) and the fact that tRNAs with seemingly unrelated codons (e.g., serine) are recognized by one enzyme (4). Studies onmodification of tRNA by UV irradiation led to the proposal that the three last base-pairs in the amino-acid acceptor stem are the specific recognition site (5).…”

mentioning

confidence: 88%

Is There a Discriminator Site in Transfer RNA?

Crothers

Seno

Söll

1972

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

210

108

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We determined the nature of the fourth nucleotide from the 3'-end of several Escherichia coli tRNAs, and tabulated these results with the same data for all known tRNA sequences. We find a striking constancy of the fourth nucleotide in tRNAs specific for a given amino acid. Furthermore, tRNAs specific for chemically related amino acids are very likely to have the same nucleotide at the fourth position.One possible explanation for these regularities is the "discriminator" hypothesis: The code by which tRNA is recognized by its cognate aminoacyl-tRNA synthetase is logically hierarchical, with the fourth nucleotide serving as a primary "discriminator" site to subdivide the tRNAs into groups for recognition purposes. Each such group could have its own recognition code, or could be further subdivided by a secondary discriminator site. According to this hypothesis, chemically similar amino acids have the same discriminator nucleotide because they evolved from a single set of related amino acids indistinguishable to a primitive system.There are other possible explanations for the observed regularities at the fourth nucleotide. For example, it is conceivable that the position is used for a direct physical interaction with the amino acid in the charging process, and chemically similar amino acids naturally select the same nucleotide. Further experiments can be expected to clarify this question.The specific recognition of a protein by a nucleic-acid macromolecule is a well studied, but still poorly understood, process. One of the best model systems for this process is the proper recognition of tRNA by the cognate aminoacyl-tRNA synthetase. This recognition must be remarkably specific in order for the enzyme to discriminate between structurally very similar tRNA molecules so as to ensure the correct translation of the genetic message. Although the great advances in the methodology of sequencing nucleic acids have provided much detailed insight into tRNA primary structure, no clear ideas on which features of the tRNA molecule are recognized by the enzyme have emerged. Indeed, a multitude of observations that are seemingly contradictory from species to species raise doubts whether there is a uniform recognition mechanism for all tRNAs (1). All this, of course, is related to the tertiary structure of tRNA which, at present, is not understood.Since the tRNAs specialize in recognizing with a high degree of fidelity very many different codons, one of the early thoughts on recognition attributed specificity to the anticodon region (2). This general notion was specifically contradicted by evidence on suppressor tRNA (3) and the fact that tRNAs with seemingly unrelated codons (e.g., serine) are recognized by one enzyme (4). Studies onmodification of tRNA by UV irradiation led to the proposal that the three last base-pairs in the amino-acid acceptor stem are the specific recognition site (5). That this simple proposal was also not universally applicable was soon evident; for instance, from studies with isoacceptor tRNAs from ...

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“…It has been shown that separate tRNA 's pecies, one responding to codons UCA and UCG and the other to AGU and AGC, compete for synthetase and are thus recognizable to the same seryl-tRNA synthetase (277). This presents some peculiar problems, particularly in the case o~ tRNÃ ot, which has codons UCU, UCC, UCA, UCG, and AGU and AGC.…”

Section: Am~noacyl-trna Syntitetasesmentioning

confidence: 99%