The activity of TRIM25 is controlled by RNA

The E3 ubiquitin ligase TRIM25 is an antiviral factor recently discovered to bind RNA by the RNA interactome studies (Castello et al., 2012 and Kwon et al., 2013). In a recent work led by our collaborator Gracjan Michlewsky (Wellcome Centre for Cell Biology, University of Edinburgh), we dissected how this protein binds to RNA and what are the consequences of this interaction in TRIM25 function. We discovered that TRIM25 binds RNA via its PRY/SPRY domain and that the interaction with RNA enhances TRIM25 E3 ligase activity, which is necessary for its antiviral role. Using CLIP analyses we showed that TRIM25 binds G-rich sequences present in hundreds of cellular RNAs. Moreover, We discovered that TRIM25 controls the levels of a key component in the interferon response pathway, ZAP (also known as PARP13 and ZC3HAV1).

In conclusion, the E3 ligase activity of TRIM25 is controlled by RNA, breaking once more the view that proteins act on RNA and not the opposite.

Original publication:
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 S. Nowak, Shaun Webb, Sander Granneman, Christos Spanos, Juri Rappsilber, Alfredo Castello and Gracjan Michlewski
BMC biology

Decapping host and viral RNAs

In a recent work with Yolanda Revilla’s lab (CBMSO, Madrid) published in the Journal of Virology, we investigated the role in RNA metabolism of a protein from a complex DNA virus, called African swine fever virus (ASFV). This protein exhibits high homology with cellular decapping enzymes and thus can potentially remove the cap structure from the RNA body triggering degradation.  We show that this protein interacts with viral and cellular mRNAs in infected cells. This interaction results in decreased levels of both types of transcripts, agreeing with a putative role as virus-encoded decapping activity. We propose that the degradation of RNA triggered by this protein is key to control gene expression in ASFV infected cells.