Linked Life Data

2659081

Source:http://linkedlifedata.com/resource/pubmed/id/2659081

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1989-7-27
pubmed:abstractText
A single G3.U70 base pair in the acceptor helix is a major determinant of the identity of an alanine transfer RNA. Alteration of this base pair to A.U or G.C prevents aminoacylation with alanine. We show here that, at approximate physiological conditions (pH 7.5, 37 degrees C), high concentrations of the mutant A3.U70 species do not inhibit aminoacylation of a wild-type alanine tRNA. The observation suggests that, under these conditions, the G3 to A3 substitution increases Km for tRNA by more than 30-fold. Other experiments at pH 7.5 show that no aminoacylation of A3.U70, G3.C70, or U3.G70 mutant tRNAs occurs with substrate levels of enzyme. This suggests that kcat for these mutant tRNAs is sharply reduced as well and that the catalytic defect is not due to slow release of charged mutant tRNAs from the enzyme. Investigations were also done at pH 5.5, where association of tRNAs with synthetases is generally stronger and where binding can be conveniently measured apart from aminoacylation. Under these conditions, the binding of the A3.U70 and G3.C70 species is readily detected and is only 3-5-fold weaker than the binding of the wild-type tRNA. Although the A3.U70 species was demonstrated to compete with the wild-type tRNA for the same site on the enzyme, no aminoacylation could be detected. Thus, even when conditions are adjusted to obtain strong competitive binding, a sharp reduction in kcat prevents aminoacylation of a tRNA(Ala) species with a substitution at position 3.70.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
28
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2740-6
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
A single base pair affects binding and catalytic parameters in the molecular recognition of a transfer RNA.
pubmed:affiliation
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.