Crystal structure of the complete core of archaeal signal recognition particle and implications for interdomain communication.
Targeting of secretory and membrane proteins by the signal recognition particle (SRP) is evolutionarily conserved, and the multidomain protein SRP54 acts as the key player in SRP-mediated protein transport. Binding of a signal peptide to SRP54 at the ribosome is coordinated with GTP binding and subsequent complex formation with the SRP receptor. Because these functions are localized to distinct domains of SRP54, communication between them is essential. We report the crystal structures of SRP54 from the Archaeon Sulfolobus solfataricus with and without its cognate SRP RNA binding site (helix 8) at 4-A resolution. The two structures show the flexibility of the SRP core and the position of SRP54 relative to the RNA. A long linker helix connects the GTPase (G domain) with the signal peptide binding (M) domain, and a hydrophobic contact between the N and M domains relates the signal peptide binding site to the G domain. Hinge regions are identified in the linker between the G and M domains (292-LGMGD) and in the N-terminal part of the M domain, which allow for structural rearrangements within SRP54 upon signal peptide binding at the ribosome.
Rosendal
Ken R
KR
Biochemie-Zentrum Heidelberg, INF 328, D-69120 Heidelberg, Germany.
Wild
Klemens
K
Montoya
Guillermo
G
Sinning
Irmgard
I
D000595:Amino Acid Sequence; D001105:Archaea / Q000378:metabolism*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004583:Electrons; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010455:Peptides / Q000737:chemistry; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; D017386:Sequence Homology, Amino Acid; D018271:Signal Recognition Particle / Q000737:chemistry*; D016944:Sulfolobus / Q000378:metabolism
D010455:Peptides; D021382:Protein Sorting Signals; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; C480632:SRP54 protein, human; D018271:Signal Recognition Particle; C036318:signal peptide receptor; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases