2DB4 image
Deposition Date 2005-12-15
Release Date 2006-12-05
Last Version Date 2024-10-16
Entry Detail
PDB ID:
2DB4
Keywords:
Title:
Crystal structure of rotor ring with DCCD of the V- ATPase from Enterococcus hirae
Biological Source:
Source Organism:
Host Organism:
Method Details:
Experimental Method:
Resolution:
2.40 Å
R-Value Free:
0.23
R-Value Work:
0.22
R-Value Observed:
0.22
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:V-Type Sodium ATPase Subunit K
Gene (Uniprot):ntpK
Chain IDs:A, B, C, D, E, F, G, H, I, J
Chain Length:156
Number of Molecules:10
Biological Source:Enterococcus hirae
Primary Citation
Structure of the rotor ring modified with N,N'-dicyclohexylcarbodiimide of the Na+-transporting vacuolar ATPase.
Proc.Natl.Acad.Sci.USA 108 13474 13479 (2011)
PMID: 21813759 DOI: 10.1073/pnas.1103287108

Abstact

The prokaryotic V-ATPase of Enterococcus hirae, closely related to the eukaryotic enzymes, provides a unique opportunity to study the ion-translocation mechanism because it transports Na(+), which can be detected by radioisotope (22Na(+)) experiments and X-ray crystallography. In this study, we demonstrated that the binding affinity of the rotor ring (K ring) for 22Na(+) decreased approximately 30-fold by reaction with N,N(')-dicyclohexylcarbodiimide (DCCD), and determined the crystal structures of Na(+)-bound and Na(+)-unbound K rings modified with DCCD at 2.4- and 3.1-Å resolutions, respectively. Overall these structures were similar, indicating that there is no global conformational change associated with release of Na(+) from the DCCD-K ring. A conserved glutamate residue (E139) within all 10 ion-binding pockets of the K ring was neutralized by modification with DCCD, and formed an "open" conformation by losing hydrogen bonds with the Y68 and T64 side chains, resulting in low affinity for Na(+). This open conformation is likely to be comparable to that of neutralized E139 forming a salt bridge with the conserved arginine of the stator during the ion-translocation process. Based on these findings, we proposed the ion-translocation model that the binding affinity for Na(+) decreases due to the neutralization of E139, thus releasing bound Na(+), and that the structures of Na(+)-bound and Na(+)-unbound DCCD-K rings are corresponding to intermediate states before and after release of Na(+) during rotational catalysis of V-ATPase, respectively.

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