Biomedical subjects

B LaRue

Publications and source records attributed to B LaRue.

3 recordsLinked to original sources

PubMed1981

The evolution of multi-isoacceptor tRNA families. Sequence of tRNA Leu CAA and tRNA Leu CAG from Anacystis nidulans.

Two leucine tRNAs from the cyanophyte Anacystis nidulans have been isolated, and their complete nucleotide sequences have been determined by combining data from oligonucleotide fingerprints and sequencing gels. The two sequences are 87 nucleotides long, have the anticodons CAA and CAG, and differ from each other at a total of 28 positions. They have been compared to other known tRNA Leu sequences and incorporated into a phylogenetic tree comprising prokaryotic and chloroplastic tRNA Leu sequences. Mutations inferred from the tree show that some parts of the tRNA molecule are highly variable (the extra arm and the acceptor stem) while others are much more conserved (the D and T arms). The topology of the tree supports the idea that blue-green algae and chloroplasts share a common prokaryotic ancestor and show a basic divergence between XAA and XAG anticodon-containing tRNAs, suggesting that these two subfamilies result from an ancient gene duplication. Finally, comparison of this phylogenetic tree with those of other multi-isoacceptor tRNA families shows no common scheme, which may be due to independent refinement of codon-reading patterns in different tRNA families.

Base Sequence↗

PubMed1981

The evolving tRNA molecule.

The study of tRNA molecular evolution is crucial to understanding the origin and establishment of the genetic code as well as the differentiation and refinement of the machinery of protein synthesis in prokaryotes, eukaryotes, organelles, and phage systems. The small size of the molecule and its critical involvement in a multiplicity of roles distinguish its study from classical protein molecular evolution with respect to goals and methods. Here, the authors assess available and missing data, existing and needed methodology, and the impact of tRNA studies on current theories both of genetic code evolution and of the evolution of species. They analyze mutational "hot spots", the role of base modification, synthetase recognition, codon-anticodon interactions and the status of organelle tRNA.

Animals↗

PubMed1980

Convergence and minimal mutation criteria for evaluating early events in tRNA evolution.

The convergence of ancestral sequences independently constructed from different branches of a phylogenetic tree can be used as a test of homology of data sequences. This criterion has shown that all phenylalanine tRNAs are related to a common ancestor, whereas eukaryotic and prokaryotic tyrosine tRNAs may have independent origins. All glycine tRNAs share a common ancestor. The glycine tRNA family splits according to the purine or pyrimidine nature of the first anticodon base prior to the divergence of eukaryotes and prokaryotes. The structural similarity between some prokaryotic glycine and and valine tRNAs is the result of their derivation from a common ancestor that existed previous to the divergence of the different glycine tRNAs. These results support models of genetic code evolution involving the incremental elaboration of earlier, simpler codes.

Animals↗