Inter-domain Motions of the N-domain of the KdpFABC Complex, a P-type ATPase, are not Driven by ATP-induced Conformational Changes
Copyright policy )Inter-domain Motions of the N-domain of the KdpFABC Complex, a P-type ATPase, are not Driven by ATP-induced Conformational Changes
P-type ATPases are involved in the active transport of ions across biological membranes. The KdpFABC complex (P-type ATPase) of Escherichia coli is a high-affinity K+ uptake system that operates only when the cell experiences osmotic stress or K+ limitation. Here, we present the solution structure of the nucleotide binding domain of KdpB (backbone RMSD 0.17 A) and a model of the AMP-PNP binding mode based on intermolecular distance restraints. The calculated AMP-PNP binding mode shows the purine ring of the nucleotide to be "clipped" into the binding pocket via a pi-pi-interaction to F377 on one side and a cation-pi-interaction to K395 on the other. This binding mechanism seems to be conserved in all P-type ATPases, except the heavy metal transporting ATPases (type IB). Thus, we conclude that the Kdp-ATPase (currently type IA) is misgrouped and has more similarities to type III ATPases. The KdpB N-domain is the smallest and simplest known for a P-type ATPase, and represents a minimal example of this functional unit. No evidence of significant conformational changes was observed within the N-domain upon nucleotide binding, thus ruling out a role for ATP-induced conformational changes in the reaction cycle.
- Technical University of Munich Germany
- Osnabrück University Germany
Adenosine Triphosphatases, Models, Molecular, Binding Sites, Sequence Homology, Amino Acid, Protein Conformation, Escherichia coli Proteins, Adenylyl Imidodiphosphate, Molecular Sequence Data, Protein Structure, Tertiary, Solutions, Adenosine Triphosphate, Escherichia coli, Amino Acid Sequence, Cation Transport Proteins, Protein Binding
Adenosine Triphosphatases, Models, Molecular, Binding Sites, Sequence Homology, Amino Acid, Protein Conformation, Escherichia coli Proteins, Adenylyl Imidodiphosphate, Molecular Sequence Data, Protein Structure, Tertiary, Solutions, Adenosine Triphosphate, Escherichia coli, Amino Acid Sequence, Cation Transport Proteins, Protein Binding
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