2a29
The solution structure of the AMP-PNP bound nucleotide binding domain of KdpB
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OverviewOverview
P-type ATPases are ubiquitously abundant enzymes involved in active, transport of charged residues across biological membranes. The KdpB, subunit of the prokaryotic Kdp-ATPase (KdpFABC complex) shares, characteristic regions of homology with class II-IV P-type ATPases and has, been shown previously to be misgrouped as a class IA P-type ATPase. Here, we present the NMR structure of the AMP-PNP-bound nucleotide binding, domain KdpBN of the Escherichia coli Kdp-ATPase at high resolution. The, aromatic moiety of the nucleotide is clipped into the binding pocket by, Phe(377) and Lys(395) via a pi-pi stacking and a cation-pi interaction, respectively. Charged residues at the outer rim of the binding pocket, (Arg(317), Arg(382), Asp(399), and Glu(348)) stabilize and direct the, triphosphate group via electrostatic attraction and repulsion toward the, phosphorylation domain. The nucleotide binding mode was corroborated by, the replacement of critical residues. The conservative mutation F377Y, produced a high residual nucleotide binding capacity, whereas replacement, by alanine resulted in low nucleotide binding capacities and a, considerable loss of ATPase activity. Similarly, mutation K395A resulted, in loss of ATPase activity and nucleotide binding affinity, even though, the protein was properly folded. We present a schematic model of the, nucleotide binding mode that allows for both high selectivity and a low, nucleotide binding constant, necessary for the fast and effective turnover, rate realized in the reaction cycle of the Kdp-ATPase.
About this StructureAbout this Structure
2A29 is a Single protein structure of sequence from Escherichia coli with ANP as ligand. This structure superseeds the now removed PDB entry 1X6K. Active as Potassium-transporting ATPase, with EC number 3.6.3.12 Full crystallographic information is available from OCA.
ReferenceReference
The holo-form of the nucleotide binding domain of the KdpFABC complex from Escherichia coli reveals a new binding mode., Haupt M, Bramkamp M, Heller M, Coles M, Deckers-Hebestreit G, Herkenhoff-Hesselmann B, Altendorf K, Kessler H, J Biol Chem. 2006 Apr 7;281(14):9641-9. Epub 2005 Dec 14. PMID:16354672
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