Poster abstracts
Poster number 44 submitted by Jun-Kyu Byun
Role of Unique C-terminal Domain in a Plant Aminoacyl-tRNA Trans-editing Protein
Jun-Kyu Byun (The Ohio State Biochemistry Program), William A. Cantara, John Vu, Jyan-Chyun Jang, Karin Musier-Forsyth (Department of Chemistry Biochemistry)
Abstract:
Some aminoacyl-tRNA synthetases (aaRSs) are error-prone, mispairing noncognate amino acids with cognate tRNAs. To prevent mistranslation, many aaRSs have evolved quality control mechanisms. Bacterial prolyl-tRNA synthetases (ProRSs) mischarge noncognate Ala onto tRNAPro and possess an insertion (INS) domain that can deacylate Ala-tRNAPro. However, some bacteria and all eukaryotes lack an INS domain and instead, encode a free-standing trans-editing domain homolog, ProXp-ala Sequence alignments revealed that all plant ProXp-ala encode a unique, conserved C-terminal domain (CTD) that is missing from all other eukaryotic ProXp-ala. The CTD is predicted to encode a long helical segment connected to the catalytic domain via a random coil. Additional domains can be indicative of enhanced specificity or editing activity, but could also impart new functions. To determine the function of the CTD, we prepared a truncated Arabidopsis thaliana (At) ProXp-ala variant (ΔC-ProXp-ala). The in vitro Ala-tRNAPro deacylation rate by ΔC-ProXp-ala was decreased 16-fold relative to wild-type (WT) ProXp-ala, primarily due to a tRNA binding defect. In addition, multiangle laser light scattering analysis shows that WT At ProXp-ala adopts several oligomeric states while ΔC-ProXp-ala is exclusively monomeric. The CTD, therefore, enhances tRNA binding and induces oligomerization in vitro. ProXp-ala disruption strains of At showed various growth defects such as lack of germination, reduced rosette size, late flowering, and abnormal fruit development. Trans-complementation experiments are currently underway to introduce WT and ΔC-ProXp-ala into the knockout strains to better understand the functional significance of the CTD in vivo. This work will reveal how plants have uniquely evolved to avoid mistranslation and may lead to the discovery of new ProXp-ala functions.
References:
1. Das M, Vargas-Rodriguez O, Goto Y, Suga H, Musier-Forsyth K. Distinct tRNA recognition strategies used by a homologous family of editing domains prevent mistranslation. Nucleic Acids Research. 2014;42(6):3943-3953.
2. Vargas-Rodriguez O, Musier-Forsyth K. Exclusive Use of trans-Editing Domains Prevents Proline Mistranslation. The Journal of Biological Chemistry. 2013;288(20):14391-14399.
Keywords: aminoacyl tRNA synthesis , tRNA, plant