- PMID:
24700861 , Related PDB ids: 4P3E, 4P3F, 4P3G
- Authors:
- Grotwinkel JT, Wild K, Segnitz B, Sinning I
- Title:
- SRP RNA remodeling by SRP68 explains its role in protein translocation.
- Journal:
- Science. 2014 Apr 4;344(6179):101-4. doi: 10.1126/science.1249094.
- Abstract:
- The signal recognition particle (SRP) is central to membrane protein targeting; SRP RNA is essential for SRP assembly, elongation arrest, and activation of SRP guanosine triphosphatases. In eukaryotes, SRP function relies on the SRP68-SRP72 heterodimer. We present the crystal structures of the RNA-binding domain of SRP68 (SRP68-RBD) alone and in complex with SRP RNA and SRP19. SRP68-RBD is a tetratricopeptide-like module that binds to a RNA three-way junction, bends the RNA, and inserts an alpha-helical arginine-rich motif (ARM) into the major groove. The ARM opens the conserved 5f RNA loop, which in ribosome-bound SRP establishes a contact to ribosomal RNA. Our data provide the structural basis for eukaryote-specific, SRP68-driven RNA remodeling required for protein translocation.