Summary information and primary citation

4xco; DSSR-derived features in text and JSON formats
RNA binding protein
X-ray (2.9 Å)
Signal-sequence induced conformational changes in the signal recognition particle
Hainzl T, Sauer-Eriksson AE (2015): "Signal-sequence induced conformational changes in the signal recognition particle." Nat Commun, 6, 7163. doi: 10.1038/ncomms8163.
Co-translational protein targeting is an essential, evolutionarily conserved pathway for delivering nascent proteins to the proper cellular membrane. In this pathway, the signal recognition particle (SRP) first recognizes the N-terminal signal sequence of nascent proteins and subsequently interacts with the SRP receptor. For this, signal sequence binding in the SRP54 M domain must be effectively communicated to the SRP54 NG domain that interacts with the receptor. Here we present the 2.9 Å crystal structure of unbound- and signal sequence bound SRP forms, both present in the asymmetric unit. The structures provide evidence for a coupled binding and folding mechanism in which signal sequence binding induces the concerted folding of the GM linker helix, the finger loop, and the C-terminal alpha helix αM6. This mechanism allows for a high degree of structural adaptability of the binding site and suggests how signal sequence binding in the M domain is coupled to repositioning of the NG domain.

Cartoon-block schematics in six views (download the tarball)

PyMOL session file Download PDB file View in 3Dmol.js