SUMOylation of Arginyl tRNA Synthetase Modulates the Innate Immune Response.

SUMO conjugation of a substrate protein can modify its activity, localization, interaction or function. A large number of SUMO targets in cells have been identified by Proteomics, but biological roles for SUMO conjugation for most targets remains elusive. The multi-aminoacyl tRNA synthetase complex (MARS) is a sensor and regulator of immune signaling. The proteins of this 1.2 MDa complex are targets of SUMO conjugation, in response to infection. Arginyl tRNA Synthetase (RRS), a member of the sub-complex II of MARS, is one such SUMO conjugation target. The sites for SUMO conjugation are Lys 147 and 383. Replacement of these residues by Arg (RRS ), creates a SUMO conjugation resistant variant (RRS ). Transgenic lines for RRS and RRS were generated by expressing these variants in a animal, using the UAS-Gal4 system. The - line was itself generated using CRISPR/Cas9 genome editing. Expression of both and rescue the lethality. Adult animals expressing and are compared and contrasted for their response to bacterial infection by gram positive and gram negative . We find that , when compared to , shows modulation of the transcriptional response, as measured by quantitative 3' mRNA sequencing. Our study uncovers a possible non-canonical role for SUMOylation of RRS, a member of the MARS complex, in host-defense.