Linked Life Data

2435916

Source:http://linkedlifedata.com/resource/pubmed/id/2435916

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1987-5-6
pubmed:abstractText
In previous publications, we have shown that it is practical to study the translational activity of tRNAs by replacement and alteration of the anticodon arm sequence of the genus on a plasmid clone. Experiments in which the anticodon arm sequence is transplanted between tRNA genes suggest that the translational activity is determined by these sequences. We have therefore made every variant of the anticodon loop and the three base-pairs of the stem proximal to the loop, in order to resolve the relation between the structure of Su7Am tRNATrp, and its function. All derivatives conserved the normal secondary structure of the molecule, which was known to be essential for translational activity. The probability of translation of the amber codon by these suppressors is measured in this work. This translational activity in vivo is rationalized in terms of data on the copy numbers of the plasmid clones, the nucleotide modifications of the tRNAs, the steady-state level of the mature tRNA, and the aminoacylation of these molecules. Nucleotide modification levels vary among these tRNAs, giving information about the specificities of modification systems that make O-methylribose, pseudouridine, and modified A in the anticodon arm. However, for this series of tRNAs, none of these modifications has a strong effect on translational efficiency of the tRNAs. A few of the substitutions reduce aminoacylation of the tRNAs with glutamine, as determined by comparison of suppression in normal strains and related strains, which have 25-fold elevated levels of the glutaminyl-tRNA synthetase (GlnRS). The substitutions that have the largest effect on GlnRS action are, unexpectedly, purines for conserved pyrimidines on the 5' side of the anticodon loop. Data on the concentrations of tRNA in vivo suggest that the anticodon loop and helix contribute similarly to the determination of the steady-state level of the tRNAs. This level varies sevenfold, though all tRNAs are processed from a homologous precursor made from the same transcription unit. Effects on levels appear to be mediated by changes in anticodon arm structure. A robust equation that relates aminoacyl-tRNA levels to suppressor efficiency is developed in order to resolve effects on tRNA levels and on ribosomal steps: E = A/(K + A), where E is efficiency, A is aminoacyl-tRNA concentration, and K is the effective concentration, or cellular tRNA content required for an individual tRNA to have an efficiency of 0.50. The tRNAs vary in their intrinsic ability to function on the ribosome (represented by K), after other influences have been normalized.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
20
pubmed:volume
192
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
235-55
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1986
pubmed:articleTitle
Actions of the anticodon arm in translation on the phenotypes of RNA mutants.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.