Transcriptome-wide identification of coding and noncoding RNA-binding proteins defines the extended RNA interactome of Leishmania mexicana

Non-poly(A) RNA molecules including noncoding RNAs (ncRNAs) comprise the major portion of the total transcribed molecules in the cell. In addition to the mRNAs the ncRNAs also function as ribonucleoprotein particles (RNPs) and carry out biological functions including synthesis of new proteins, RNA processing, genome remodelling and regulation of transcription. We therefore envisaged a comprehensive transcriptome-wide identification of coding and non-coding RNA-binding proteins (RBPs) in the Leishmania spp. Towards this we applied the recently reported orthogonal organic phase separation (OOPS) method in combination with tandem mass tag (TMT) labelling-based quantitative proteomic mass spectrometry (MS) and report herein the most comprehensive identification of RBPs in Leishmania mexicana (L. mexicana) parasites. This study identified novel RNA binding property of thousands of L. mexicana proteins, significantly expanding the RBP landscape of the parasite. Furthermore, we showed that the classical Hsp90 inhibitor tanespimycin differentially regulates the RNA-binding property of hundreds of L. mexicana RBPs, shedding light into hitherto unknown large-scale downstream molecular effects of the small molecule inhibitor in the parasite.