The KdpFABC complex of E. coli, a P-type ATPase (class IA), is a high-affinity K+ uptake system that operates only when the cell experiences severe K+ limitation. The tertiary structure of the nucleotide binding domain, KdpBN, was solved by solution NMR spectroscopy at a backbone RMSD of 0.17 Å over ordered residues. Furthermore, a model of the AMP-PNP binding mode based on intermolecular distance restraints from an isotope-filtered 2D NOESY spectrum revealed an hitherto unknown binding mechanism for this class of enzymes. The data were corroborated by NMR titration experiments and STD spectroscopy. The purine ring of the nucleotide is 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. The absence of residues F and K, which are crucial for the clipping-mode, in heavy metal transporting P-type ATPases (class IB) suggest a different nucleotide binding mode and therefore KdpB seems to be misgrouped as a class I P-type ATPase. Furthermore, the solution structure of cyclo(-Tic-L-D-T-D-p-), a potent α4β7 integrin antagonist, was solved by NMR spectroscopy.
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The KdpFABC complex of E. coli, a P-type ATPase (class IA), is a high-affinity K+ uptake system that operates only when the cell experiences severe K+ limitation. The tertiary structure of the nucleotide binding domain, KdpBN, was solved by solution NMR spectroscopy at a backbone RMSD of 0.17 Å over ordered residues. Furthermore, a model of the AMP-PNP binding mode based on intermolecular distance restraints from an isotope-filtered 2D NOESY spectrum revealed an hitherto unknown binding mechanis...
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