3QFU: Crystal Structure Of Yeast Hsp70 (BipKAR2) COMPLEXED WITH ADP

Sil1 functions as a NEF (nucleotide-exchange factor) for the ER (endoplasmic reticulum) Hsp70 (heat-shock protein of 70 kDa) Bip in eukaryotic cells. Sil1 may catalyse the ADP release from Bip by interacting directly with the ATPase domain of Bip. In the present study we show the complex crystal structure of the yeast Bip and the NEF Sil1 at the resolution of 2.3 A (1 A=0.1 nm). In the Sil1-Bip complex structure, the Sil1 molecule acts as a 'clamp' which binds lobe IIb of the Bip ATPase domain. The binding of Sil1 causes the rotation of lobe IIb ~ 13.5 degrees away from the ADP-binding pocket. The complex formation also induces lobe Ib to swing in the opposite direction by ~ 3.7 degrees . These conformational changes open up the nucleotide-binding pocket in the Bip ATPase domain and disrupt the hydrogen bonds between Bip and bound ADP, which may catalyse ADP release. Mutation of the Sil1 residues involved in binding the Bip ATPase domain compromise the binding affinity of Sil1 to Bip, and these Sil1 mutants also abolish the ability to stimulate the ATPase activity of Bip.
PDB ID: 3QFUDownload
MMDB ID: 91880
PDB Deposition Date: 2011/1/22
Updated in MMDB: 2011/09
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 3QFU: monomeric; determined by author and by software (PISA)
Molecular Components in 3QFU
Label Count Molecule
Protein (1 molecule)
78 KDA Glucose-regulated Protein Homolog(Gene symbol: KAR2)
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB