Structures of SRP54 and SRP19, the two proteins assembling the ribonucleic core of the Signal Recognition Particle from the archaeon Pyrococcus furiosus.

Experimental Data Snapshot

  • Resolution: 2.51 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.222 
  • R-Value Observed: 0.223 

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Structures of SRP54 and SRP19, the two proteins that organize the ribonucleic core of the signal recognition particle from Pyrococcus furiosus.

Egea, P.F.Napetschnig, J.Walter, P.Stroud, R.M.

(2008) PLoS One 3: e3528-e3528

  • DOI: https://doi.org/10.1371/journal.pone.0003528
  • Primary Citation of Related Structures:  
    3DLU, 3DLV, 3DM5

  • PubMed Abstract: 

    In all organisms the Signal Recognition Particle (SRP), binds to signal sequences of proteins destined for secretion or membrane insertion as they emerge from translating ribosomes. In Archaea and Eucarya, the conserved ribonucleoproteic core is composed of two proteins, the accessory protein SRP19, the essential GTPase SRP54, and an evolutionarily conserved and essential SRP RNA. Through the GTP-dependent interaction between the SRP and its cognate receptor SR, ribosomes harboring nascent polypeptidic chains destined for secretion are dynamically transferred to the protein translocation apparatus at the membrane. We present here high-resolution X-ray structures of SRP54 and SRP19, the two RNA binding components forming the core of the signal recognition particle from the hyper-thermophilic archaeon Pyrococcus furiosus (Pfu). The 2.5 A resolution structure of free Pfu-SRP54 is the first showing the complete domain organization of a GDP bound full-length SRP54 subunit. In its ras-like GTPase domain, GDP is found tightly associated with the protein. The flexible linker that separates the GTPase core from the hydrophobic signal sequence binding M domain, adopts a purely alpha-helical structure and acts as an articulated arm allowing the M domain to explore multiple regions as it scans for signal peptides as they emerge from the ribosomal tunnel. This linker is structurally coupled to the GTPase catalytic site and likely to propagate conformational changes occurring in the M domain through the SRP RNA upon signal sequence binding. Two different 1.8 A resolution crystal structures of free Pfu-SRP19 reveal a compact, rigid and well-folded protein even in absence of its obligate SRP RNA partner. Comparison with other SRP19*SRP RNA structures suggests the rearrangement of a disordered loop upon binding with the RNA through a reciprocal induced-fit mechanism and supports the idea that SRP19 acts as a molecular scaffold and a chaperone, assisting the SRP RNA in adopting the conformation required for its optimal interaction with the essential subunit SRP54, and proper assembly of a functional SRP.

  • Organizational Affiliation

    Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA. pascal@msg.ucsf.edu

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Signal recognition 54 kDa protein
A, B
443Pyrococcus furiosusMutation(s): 0 
Gene Names: srp54PF1731
Find proteins for Q8U070 (Pyrococcus furiosus (strain ATCC 43587 / DSM 3638 / JCM 8422 / Vc1))
Explore Q8U070 
Go to UniProtKB:  Q8U070
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8U070
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on GDP

Download Ideal Coordinates CCD File 
J [auth A],
Q [auth B]
C10 H15 N5 O11 P2
Query on SO4

Download Ideal Coordinates CCD File 
C [auth A]
D [auth A]
E [auth A]
F [auth A]
G [auth A]
C [auth A],
D [auth A],
E [auth A],
F [auth A],
G [auth A],
H [auth A],
K [auth B],
L [auth B],
M [auth B],
N [auth B],
O [auth B]
O4 S
Query on ACT

Download Ideal Coordinates CCD File 
I [auth A],
P [auth B]
C2 H3 O2
Experimental Data & Validation

Experimental Data

  • Resolution: 2.51 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.222 
  • R-Value Observed: 0.223 
  • Space Group: P 42 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 127.009α = 90
b = 127.009β = 90
c = 186.836γ = 90
Software Package:
Software NamePurpose
HKL-2000data reduction
SCALEPACKdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-11-04
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2017-10-25
    Changes: Advisory, Refinement description
  • Version 1.3: 2024-02-21
    Changes: Advisory, Data collection, Database references, Derived calculations