Molecular architecture of LSM14 interactions involved in the assembly of mRNA silencing complexes
- EMBO J. 2018 Apr 3;37(7):e97869. doi: 10.15252/embj.201797869.
- 1. Department of Biochemistry, University of Zurich, Zurich, Switzerland.
- 2. Department of Oncology, McGill University, Montreal, QC, Canada.
- 3. Segal Cancer Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada.
- 4. Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada.
- 5. Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
- 6. Department of Oncology, McGill University, Montreal, QC, Canada [email protected] [email protected].
- 7. Department of Biochemistry, University of Zurich, Zurich, Switzerland [email protected] [email protected].
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 4E-T C-terminus forms a bi-partite motif that wraps around the N-terminal LSM domain of LSM14. We also determined the crystal structure of LSM14 bound to the C-terminal RecA-like domain of DDX6. LSM14 binds DDX6 via a unique non-contiguous motif with distinct directionality as compared to Other DDX6-interacting proteins. Together with mutational and proteomic studies, the LSM14-DDX6 structure reveals that LSM14 has adopted a divergent mode of binding DDX6 in order to support the formation of mRNA silencing complexes and P-body assembly.