Description
Experimental Technique/Method:X-RAY DIFFRACTION
Resolution:2.05
Classification:RIBONUCLEOPROTEIN
Release Date:1997-12-31
Deposition Date:1996-12-30
Revision Date:2008-03-24#2011-07-13
Molecular Weight:32280.55
Macromolecule Type:Protein
Residue Count:294
Atom Site Count:2226
DOI:10.2210/pdb1ffh/pdb
Abstract:
The signal-recognition particle (SRP) and its receptor (SR) function in the co-translational targeting of nascent protein-ribosome complexes to the membrane translocation apparatus. The SRP protein subunit (termed Ffh in bacteria) that recognizes the signal sequence of nascent polypeptides is a GTPase, as is the SR-alpha subunit (termed FtsY). Ffh and FtsY interact directly, each stimulating the GTP hydrolysis activity of the other. The sequence of Ffh suggests three domains: an amino-terminal N domain of unknown function, a central GTPase G domain, and a methionine-rich M domain that binds both SRP RNA and signal peptides. Sequence conservation suggests that structurally similar N and G domains are present in FtsY. Here we report the structure of the nucleotide-free form of the NG fragment of Ffh. Consistent with a role for apo Ffh in protein targeting, the side chains of the empty active-site pocket form a tight network of interactions which may stabilize the nucleotide-free protein. The structural relationship between the two domains suggests that the N domain senses or controls the nucleotide occupancy of the GTPase domain. A structural subdomain unique to these evolutionarily conserved GTPases constitutes them as a distinct subfamily in the GTPase superfamily.
Resolution:2.05
Classification:RIBONUCLEOPROTEIN
Release Date:1997-12-31
Deposition Date:1996-12-30
Revision Date:2008-03-24#2011-07-13
Molecular Weight:32280.55
Macromolecule Type:Protein
Residue Count:294
Atom Site Count:2226
DOI:10.2210/pdb1ffh/pdb
Abstract:
The signal-recognition particle (SRP) and its receptor (SR) function in the co-translational targeting of nascent protein-ribosome complexes to the membrane translocation apparatus. The SRP protein subunit (termed Ffh in bacteria) that recognizes the signal sequence of nascent polypeptides is a GTPase, as is the SR-alpha subunit (termed FtsY). Ffh and FtsY interact directly, each stimulating the GTP hydrolysis activity of the other. The sequence of Ffh suggests three domains: an amino-terminal N domain of unknown function, a central GTPase G domain, and a methionine-rich M domain that binds both SRP RNA and signal peptides. Sequence conservation suggests that structurally similar N and G domains are present in FtsY. Here we report the structure of the nucleotide-free form of the NG fragment of Ffh. Consistent with a role for apo Ffh in protein targeting, the side chains of the empty active-site pocket form a tight network of interactions which may stabilize the nucleotide-free protein. The structural relationship between the two domains suggests that the N domain senses or controls the nucleotide occupancy of the GTPase domain. A structural subdomain unique to these evolutionarily conserved GTPases constitutes them as a distinct subfamily in the GTPase superfamily.
| Date made available | 1997 |
|---|---|
| Publisher | RCSB-PDB |