Understanding the protein-protein and protein-RNA interactions leading to liquid-liquid phase separation

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eIF4B is an RNA-binding protein involved in the regulation of the initiation stage/translation of the protein synthesis. eIF4B has been reported to bind several proteins related to translation, ribosomal RNA and mRNA, but again only in a few studies. On the contrary, eIF4B is not so much explored except for the RRM domain, since it is an IDP and also hard to study as it can display phase separation. I have used FRET-based approaches, NMR, and advanced biophysical techniques to answer these questions. The result shows that eIF4B undergoes liquid-liquid phase separation in a concentration-dependent manner and binds a wide range of RNA.

The picornaviral 3C(D) protein is a crucial protease that cleaves viral polyproteins and host cell defense proteins. It interacts with cis-acting replication elements (CREs) to control viral replication and translation, crucial for the viral life cycle timing. However, the molecular details of the 3C(D) and RNA interaction are poorly understood. Biophysical techniques like NMR, AUC, SAXS, and DIC microscopy have been used to study the sequence and structure determinants of RNA binding to PV-3C(D). The results show that PV-3C(D) binds a wide range of RNA with little to no sequence and structure dependence. This suggests that PV-3C(D) may play a role in virally induced apoptosis and virus spread.

 

 

 

Figure 1: eIF4B protein undergoes liquid-liquid phase separation (LLPS) in vitro (personal experimental data).