Poster abstracts
Poster number 24 submitted by Alezandra Hernandez
Characterization of an Arabidopsis thaliana tRNA trans-editing domain
Alezandra M. Hernndez Mrquez (Department of Chemistry and Biochemistry,The Ohio State University)
Abstract:
Aminoacyl tRNA-synthetases (aaRS) are a conserved family of enzymes responsible for the correct aminoacylation of cognate amino acids to their tRNA adaptors, ensuring the faithful translation of the genetic code. However, due to the similarity in amino acid size and structure, aaRSs mis-aminoacylate amino acids in vitro at a rate that is much higher than the observed rate of mistranslation in vivo (1 in 10,000 codons). Thus, tRNA proofreading or editing mechanisms are in place that can correct mischarging events. Editing mechanisms have been extensively studied in bacteria but are less well-understood in eukaryotes. Here, we characterize a trans-editing domain, ProXp-ala, that edits mischarging of tRNAPro with Ala in the plant model system Arabidopsis thaliana. No aberrant phenotype was identified in knock-down mutants of this editing domain, suggesting that an additional enzyme may function in this role. Another ProXp-ala editing domain homolog found in Trypanosoma brucei, Multi-aminoacyl-tRNA synthetase Complex-associated Protein 3 (MCP3) also displays robust Ala-tRNAPro editing function. Arabidopsis thaliana encodes an MCP3 homolog, which we hypothesize may provide a redundant editing function that rescues defects caused by the deletion of ProXp-ala. Preliminary in vitro deacylation studies support this hypothesis and subcellular localization studies performed with ProXp-Ala and MCP3 revealed localization of both proteins in the cytoplasm and nucleus. Experiments to further define the localization and substrate specificity are in progress.
Keywords: tRNA, Arabidopsis thaliana, RNA