Publication Date:
1998-03-28
Description:
The transfer RNA (tRNA) multigene family comprises 20 amino acid-accepting groups, many of which contain isoacceptors. The addition of isoacceptors to the tRNA repertoire was critical to establishing the genetic code, yet the origin of isoacceptors remains largely unexplored. A model of tRNA evolution, termed "tRNA gene recruitment," was formulated. It proposes that a tRNA gene can be recruited from one isoaccepting group to another by a point mutation that concurrently changes tRNA amino acid identity and messenger RNA coupling capacity. A test of the model showed that an Escherichia coli strain, in which the essential tRNAUGUThr gene was inactivated, was rendered viable when a tRNAArg with a point mutation that changed its anticodon from UCU to UGU (threonine) was expressed. Insertion of threonine at threonine codons by the "recruited" tRNAArg was corroborated by in vitro aminoacylation assays showing that its specificity had been changed from arginine to threonine. Therefore, the recruitment model may account for the evolution of some tRNA genes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Saks, M E -- Sampson, J R -- Abelson, J -- GM 48560/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1998 Mar 13;279(5357):1665-70.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Biology 147-75, California Institute of Technology, Pasadena, CA 91125, USA. peggy@seqaxp.bio.caltech.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9497276" target="_blank"〉PubMed〈/a〉
Keywords:
Anticodon/*genetics
;
Arginine/metabolism
;
Base Composition
;
Base Sequence
;
Escherichia coli/*genetics
;
*Evolution, Molecular
;
Genes, Bacterial
;
Haemophilus influenzae/genetics
;
Models, Genetic
;
Molecular Sequence Data
;
Multigene Family
;
Nucleic Acid Conformation
;
*Point Mutation
;
Polymerase Chain Reaction
;
RNA, Bacterial/chemistry/genetics/metabolism
;
RNA, Transfer, Arg/chemistry/*genetics/metabolism
;
RNA, Transfer, Thr/chemistry/*genetics/metabolism
;
Recombination, Genetic
;
Temperature
;
Threonine/metabolism
;
Transformation, Bacterial
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
