Biological roles of SUMOylation of Arginyl tRNA synthetase

Abstract

Aminoacyl tRNA synthetases (aaRS), many of which are components of the 1.2 Megadalton Multiple aminoacyl tRNA complex (MARS), are SUMO-conjugated in response to infection (Handu et al. 2015) in Drosophila, suggesting that this post-translational modification (PTM) of AARS is part of host-defense response to pathogens. Small Ubiquitin like modifier (SUMO) is an important post translational (PTM) in the cell, with 10-30% of cellular proteins being SUMO conjugated. We are studying the SUMOylation of Arginyl tRNA synthetase (RRS) and its role in the fly immune response. First, we validated the SUMOylation of RRS. Next, we used lysine mutagenesis to identify K147 and K383 as SUMO targets. The RRS (K147R, K383R) double mutant appears to be resistant to SUMO conjugation (RRSSCR). In order to uncover roles for SUMOylation, we planned to compare the immune response of RRSwt and RRSSCR. To achieve this, our strategy was two-fold. One, we generated RRSnull animals using CRISPR/Cas9 based gene editing. The null animals were rescued with RRSwt and RRSSCR transgenes; using the UAS/Gal4 system. Two, we planned to use CRISPR/Cas9 editing to directly edit the RRS genomic locus and replace codons for K147 and K383 with those that code for Arginine. The transgenic RRSSCR animal, once generated through either one or both of the strategies listed above will be used to uncover biological roles for SUMO conjugation of RRS, in the context of the immune response.