TheDrosophilaRNA binding protein Hrp48 binds a specific RNA sequence of themsl-2mRNA 3’ UTR to regulate translation

Abstract

AbstractRepression ofmsl-2mRNA translation is essential for viability ofDrosophila melanogasterfemales to prevent hypertranscription of both X chromosomes. This translational control event is coordinated by the female-specific protein Sex-lethal (Sxl) which recruits the RNA binding proteins Unr and Hrp48 to the 3’ untranslated region (UTR) of themsl-2transcript and represses translation initiation. The mechanism exerted by Hrp48 during translation repression and its interaction withmsl-2are not well understood. Here we investigate the RNA binding specificity and affinity of the tandem RNA recognition motifs of Hrp48. Using NMR spectroscopy, molecular dynamics simulations and isothermal titration calorimetry, we identified the exact region ofmsl-23’ UTR recognized by Hrp48. Additional biophysical experiments and translation assays give further insights into complex formation of Hrp48, Unr, Sxl and RNA. Our results show that Hrp48 binds independent of Sxl and Unr downstream of the E and F binding sites of Sxl and Unr tomsl-2.