Molecular architecture of LSM14 interactions involved in the assembly of mRNA silencing complexes.

The LSM domain-containing protein LSM14/Rap55 plays a role in mRNA decapping, translational repression, and RNA granule (P-body) assembly. How LSM14 interacts with the mRNA silencing machinery, including the eIF4E-binding protein 4E-T and the DEAD-box helicase DDX6, is poorly understood. Here we report the crystal structure of the LSM domain of LSM14 bound to a highly conserved C-terminal fragment of 4E-T.

The eIF4E-Binding Protein 4E-T Is a Component of the mRNA Decay Machinery that Bridges the 5' and 3' Termini of Target mRNAs.

Eukaryotic mRNA degradation often initiates with the recruitment of the CCR4-NOT deadenylase complex and decay factors to the mRNA 3' terminus. How the 3'-proximal decay machinery interacts with the 5'-terminal cap structure in order to engender mRNA decapping and 5'-3' degradation is unclear. Human 4E-T is an eIF4E-binding protein that has been reported to promote mRNA decay, albeit via an unknown mechanism.