Substrate Recognition by Novel Family of Amino Acid:[Carrier Protein] Ligases

Močibob, Marko and Ivić, Nives and Šubašić, Deni and Luić, Marija and Weygand-Đurašević, Ivana (2011) Substrate Recognition by Novel Family of Amino Acid:[Carrier Protein] Ligases. Croatica Chemica Acta, 84 (2). pp. 149-157. ISSN 0011-1643

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Amino acid:[carrier protein] ligases (aa:CP ligases) are newly discovered homologs of aminoacyl-tRNA synthetases(aaRS) which aminoacylate carrier proteins instead of tRNA. Activated amino acids are attached to prosthetic group of carrier proteins by thioester bond. Weak thioacylation activity was observed for many conventional aaRS. Therefore, different thiols were investigated as substrate analogs for aa:CP ligases. Here we show that coenzyme A, dithiothreitol and cysteine are efficiently aminoacylated by aa:CP ligases. The crystal structure of aa:CP ligase from Bradyrhizobium japonicum in complex with coenzyme A was solved, and revealed that CoA, besides acting as the substrate analog of the carrier protein, also competes with ATP for binding to the active site. aa:CP ligases do not aminoacylate tRNA, although they remarkably resemble catalytic core of atypical seryl-tRNA synthetases (aSerRS) from methanogenic archaea. Since aa:CP ligases lack tRNA-binding domain, fusion proteins of aa:CP ligases and aSerRS tRNA-binding domain were prepared in attempt to restore tRNA aminoacylation activity. Although fusion proteins were able to bind tRNA through appended domain, tRNA could not substitute carrier proteins in aminoacylation reaction.

Item Type: Article
Keywords: aminoacyl-tRNA synthetase, amino acid:[carrier protein] ligase, carrier protein, coenzyme A, seryl-tRNA synthetase, thioester, tRNA
Date: 2011
Subjects: NATURAL SCIENCES > Chemistry
Divisions: Faculty of Science > Department of Chemistry
Publisher: Hrvatsko kemijsko društvo
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Depositing User: Branka Maravic
Date Deposited: 08 May 2014 13:07
Last Modified: 08 May 2014 13:07

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