RNA-binding activity of TRIM25 is mediated by its PRY/SPRY domain and is required for ubiquitination

Nila Roy Choudhury; Gregory Heikel; Maryia Trubitsyna; Peter Kubik; Jakub Stanislaw Nowak; Shaun Webb; Sander Granneman; Christos Spanos; Juri Rappsilber; Alfredo Castello; Gracjan Michlewski

In the future, it will be interesting to check if any of these motifs contribute towards TRIM25's RNA-binding specificity. Next, we assessed the distribution of TRIM25 binding in mRNAs. This revealed that most binding sites are in exons (56%), with the 3'UTR also prominently represented (23%) (Fig. 4d) . Furthermore, we observed a noticeable enrichment of TRIM25 clusters just after the stop codon (Fig. 4e ). TRIM25 binds to its own transcript, which could be biologically important ( Figure S3b ). Intriguingly, even though TRIM25 is localized to both nucleus and cytoplasm (Choudhury et al., 2014) intron binding events were not common in CLIP-seq analysis. This could be demonstrated on TRIM25 mRNA target -c-Myc. Both high throughput CLIP-seq and TRIM25 RNA Immunoprecipitation (RIP) followed by targeted amplification of c-Myc transcript showed that TRIM25 predominantly interacts with mature mRNA ( Figure S3c -S3d). Nevertheless, TRIM25 interacts with many RNA-binding proteins (Fig. 3) and they could provide a platform for interactions with other targets at the level of pre-mRNAs.