A noncognate aminoacyl-tRNA synthetase that may resolve a missing link in protein evolution.
Proc Natl Acad Sci U S A
; 100(20): 11297-302, 2003 Sep 30.
Article
em En
| MEDLINE
| ID: mdl-13679580
ABSTRACT
Efforts to delineate the advent of many enzymes essential to protein translation are often limited by the fact that the modern genetic code evolved before divergence of the tree of life. Glutaminyl-tRNA synthetase (GlnRS) is one noteworthy exception to the universality of the translation apparatus. In eukaryotes and some bacteria, this enzyme is essential for the biosynthesis of Gln-tRNAGln, an obligate intermediate in translation. GlnRS is absent, however, in archaea, and most bacteria, organelles, and chloroplasts. Phylogenetic analyses predict that GlnRS arose from glutamyl-tRNA synthetase (GluRS), via gene duplication with subsequent evolution of specificity. A pertinent question to ask is whether, in the advent of GlnRS, a transient GluRS-like intermediate could have been retained in an extant organism. Here, we report the discovery of an essential GluRS-like enzyme (GluRS2), which coexists with another GluRS (GluRS1) in Helicobacter pylori. We show that GluRS2's primary role is to generate Glu-tRNAGln, not Glu-tRNAGlu. Thus, GluRS2 appears to be a transient GluRS-like ancestor of GlnRS and can be defined as a GluGlnRS.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Evolução Molecular
/
Aminoacil-tRNA Sintetases
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Estados Unidos