Publication Date:
1991-06-21
Description:
The nucleotides crucial for the specific aminoacylation of yeast tRNA(Asp) by its cognate synthetase have been identified. Steady-state aminoacylation kinetics of unmodified tRNA transcripts indicate that G34, U35, C36, and G73 are important determinants of tRNA(Asp) identity. Mutations at these positions result in a large decrease (19- to 530-fold) of the kinetic specificity constant (ratio of the catalytic rate constant kcat and the Michaelis constant Km) for aspartylation relative to wild-type tRNA(Asp). Mutation to G10-C25 within the D-stem reduced kcat/Km eightfold. This fifth mutation probably indirectly affects the presentation of the highly conserved G10 nucleotide to the synthetase. A yeast tRNA(Phe) was converted into an efficient substrate for aspartyl-tRNA synthetase through introduction of the five identity elements. The identity nucleotides are located in regions of tight interaction between tRNA and synthetase as shown in the crystal structure of the complex and suggest sites of base-specific contacts.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Putz, J -- Puglisi, J D -- Florentz, C -- Giege, R -- New York, N.Y. -- Science. 1991 Jun 21;252(5013):1696-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratoire de Biochimie, Institut de Biologie Moleculaire et Cellulaire du CNRS, Strasbourg, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2047878" target="_blank"〉PubMed〈/a〉
Keywords:
Aspartate-tRNA Ligase/*metabolism
;
Base Sequence
;
Computer Graphics
;
DNA Mutational Analysis
;
Fungal Proteins/metabolism
;
Kinetics
;
Models, Molecular
;
Molecular Sequence Data
;
RNA, Fungal/metabolism
;
RNA, Transfer, Amino Acyl/metabolism
;
RNA, Transfer, Asp/*metabolism
;
Saccharomyces cerevisiae/*enzymology
;
Structure-Activity Relationship
;
Substrate Specificity
;
*Transfer RNA Aminoacylation
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
