Antagonistic roles for Ataxin-2 structured and disordered domains in RNP condensatation

Ataxin-2 is a conserved translational control protein as well as an important target for ALS therapeutics under development. Despite its clinical and biological significance, Ataxin-2’s activities, mechanisms and functions are not well understood. Using Drosophila Ataxin-2 (Atx2) we investigate how Ataxin-2 IDRs work with structured (Lsm, Lsm-AD and PAM2) domains to enable positive and negative regulation of target mRNAs. Using TRIBE (Targets of RNA-Binding Proteins Identified by Editing) technology, we identified and analysed Atx-2 target mRNAs in the Drosophila brain. We generated transgenic Drosophila melanogaster containing Atx2-ADARcd fusion protein (WT and domain deletions) controlled by Gal4-responsive UAS promoter. Using elav-Gal4 the Atx2 fusion protein was expressed in nervous system and the expression was restricted to adult flies with the use of the temperature sensitive Gal4 inhibitor, GAL80ts. Fly brains were dissected, and mRNA was sequenced using Illumina HiSeq 2500. RNA edits sites were identified using TRIBE pipeline (https://github.com/rosbashlab/TRIBE).