Details

Autor(en) / Beteiligte

• Haupt, Melina
• Bramkamp, Marc
• Coles, Murray
• Altendorf, Karlheinz
• Kessler, Horst

Titel

Inter-domain Motions of the N-domain of the KdpFABC Complex, a P-type ATPase, are not Driven by ATP-induced Conformational Changes

Ist Teil von

• Journal of molecular biology, 2004-10, Vol.342 (5), p.1547-1558

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2004

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• 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 Å) 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 π–π-interaction to F377 on one side and a cation–π-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.