Linked Life Data

1474577

Source:http://linkedlifedata.com/resource/pubmed/id/1474577

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1993-1-29
pubmed:abstractText
The discriminator nucleotide (position 73) in tRNA has long been thought to play a role in tRNA identity as it is the only variable single-stranded nucleotide that is found near the site of aminoacylation. For this reason, a complete mutagenic analysis of the discriminator in three Escherichia coli amber suppressor tRNA backgrounds was undertaken; supE and supE-G1C72 glutamine tRNAs, gluA glutamate tRNA and supF tyrosine tRNA. The effect of mutation of the discriminator base on the identity of these tRNAs in vivo was assayed by N-terminal protein sequencing of E. coli dihydrofolate reductase, which is the product of suppression by the mutated amber suppressors, and confirmed by amino acid specific suppression experiments. In addition, suppressor efficiency assays were used to estimate the efficiency of aminoacylation in vivo. Our results indicate that the supE glutamine tRNA context can tolerate multiple mutations (including mutation of the discriminator and first base-pair) and still remain predominantly glutamine-accepting. Discriminator mutants of gluA glutamate tRNA exhibit increased and altered specificity probably due to the reduced ability of other synthetases to compete with glutamyl-tRNA synthetase. In the course of these experiments, a glutamate-specific mutant amber suppressor, gluA-A73, was created. Finally, in the case of supF tyrosine tRNA, the discriminator is an important identity element with partial to complete loss of tyrosine specificity resulting from mutation at this position. It is clear from these experiments that it may not be possible to assign a specific role in tRNA identity to the discriminator. The identity of a tRNA in vivo is determined by competition among aminoacyl-tRNA synthetases, which is in turn modulated by the nucleotide substitution as well as the tRNA context.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
20
pubmed:volume
228
pubmed:geneSymbol
gluA, supE, supF
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1055-62
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Synthetase competition and tRNA context determine the in vivo identify of tRNA discriminator mutants.
pubmed:affiliation
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.