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Title: Structural insights into the polyphyletic origins of glycyl tRNA synthetases

Glycyl tRNA synthetase (GlyRS) provides a unique case among class II aminoacyl tRNA synthetases, with two clearly widespread types of enzymes: a dimeric (α 2) species present in some bacteria, archaea, and eukaryotes; and a heterotetrameric form (α 2β 2) present in most bacteria. Although the differences between both types of GlyRS at the anticodon binding domain level are evident, the extent and implications of the variations in the catalytic domain have not been described, and it is unclear whether the mechanism of amino acid recognition is also dissimilar. Here, we show that the α-subunit of the α 2β 2 GlyRS from the bacterium Aquifex aeolicus is able to perform the first step of the aminoacylation reaction, which involves the activation of the amino acid with ATP. The crystal structure of the α-subunit in the complex with an analog of glycyl adenylate at 2.8 Å resolution presents a conformational arrangement that properly positions the cognate amino acid. This work shows that glycine is recognized by a subset of different residues in the two types of GlyRS. Furthermore, a structural and sequence analysis of class II catalytic domains shows that bacterial GlyRS is closely related to alanyl tRNA synthetase, which ledmore » us to define a new subclassification of these ancient enzymes and to propose an evolutionary path of α 2β 2 GlyRS, convergent with α 2 GlyRS and divergent from AlaRS, thus providing a possible explanation for the puzzling existence of two proteins sharing the same fold and function but not a common ancestor.« less
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  1. Univ. Nacional Autonoma de Mexico, Mexico City (Mexico)
  2. Univ. Nacional Autonoma de Mexico, Mexico City (Mexico); Centro de Investigacion y Estudios Avanzados del Instituto Politecnico Nacional, Guanajuato (Mexico)
  3. Univ. of Gothenburg, Gothenburg (Sweden)
  4. Lab. de Biologie Integrative des Milieux Marins, Roscoff (France)
  5. Institute of Genetics and of Molecular and Cellular Biology, Illkirch (France)
  6. European Molecular Biology Lab., Hamburg (Germany)
  7. Centro de Investigacion y Estudios Avanzados del Instituto Politecnico Nacional, Guanajuato (Mexico)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; 085P1000817
Accepted Manuscript
Journal Name:
Journal of Biological Chemistry
Additional Journal Information:
Journal Volume: 291; Journal Issue: 28; Journal ID: ISSN 0021-9258
American Society for Biochemistry and Molecular Biology
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; 60 APPLIED LIFE SCIENCES; aminoacyl tRNA synthetase; crystal structure; molecular evolution; structure-function; substrate specificity
OSTI Identifier: