Crystal structure of the sodium-potassium pump (Na ⁺ ,K ⁺ -ATPase) with bound potassium and ouabain

Abstract

The sodium-potassium pump (Na ؉ ,K ؉ -ATPase) is responsible for establishing Na ؉ and K ؉ concentration gradients across the plasma membrane and therefore plays an essential role in, for instance, generating action potentials. Cardiac glycosides, prescribed for congestive heart failure for more than 2 centuries, are efficient inhibitors of this ATPase. Here we describe a crystal structure of Na ؉ ,K ؉ -ATPase with bound ouabain, a representative cardiac glycoside, at 2.8 Å resolution in a state analogous to E2⅐2K ؉ ⅐Pi. Ouabain is deeply inserted into the transmembrane domain with the lactone ring very close to the bound K ؉ , in marked contrast to previous models. Due to antagonism between ouabain and K ؉ , the structure represents a low-affinity ouabain-bound state. Yet, most of the mutagenesis data obtained with the high-affinity state are readily explained by the present crystal structure, indicating that the binding site for ouabain is essentially the same. According to a homology model for the high affinity state, it is a closure of the binding cavity that confers a high affinity.cardiac glycosides ͉ crystallography

Stabilisation of Na,K-ATPase structure by the cardiotonic steroid ouabain

“…[5] for a detailed discussion). Thus, the access to the ion binding site from the extracellular side is hindered and the conformational rearrangements are blocked [5,6]. Upon phosphorylation of the Na,K-ATPase the transmembrane helices aM1 and aM2 undergo a conformational change which leads to movement of the aM1-2 helices towards the inhibitor molecule, extending the network of interactions between the hydrophilic surface of the steroid part of ouabain and the protein and increasing the tightness of binding [5,26].…”

“…Crystal structures of pig and shark Na,K-ATPase in both the absence [3,4] and presence of ouabain [5,6] have been determined. There is a strong similarity between the structures of the shark and pig a-subunits, and ouabain-induced re-arrangements can be seen for the enzymes from both species.…”

Steroid-like compounds in Chinese medicines promote blood circulation via inhibition of Na+/K+-ATPase

“…The crystal structures of pig renal Na + ,K + -ATPase (PDB code 3B8E) and shark rectal gland Na + ,K + -ATPase (PDB code 3A3Y) were downloaded from Protein Data Bank and found to posses equivalent structures [7,8] . In order to facilitate docking process, the β and γ subunits of the Na + ,K + -ATPase were removed, as well as the water molecules and counter-ions surrounding the remaining α subunit.…”

A marker-free co-selection strategy for high efficiency homology-driven and NHEJ-based gene editing in human cells

“…This protocol describes a marker-free co-selection strategy for high efficiency homology-driven and NHEJ-based gene editing in human cells by generating dominant cellular resistance to ouabain, a highly potent plant-derived inhibitor of the Na + ,K + -ATPase (1,2,3). This scarless coconversion strategy is highly efficient and can yield a stable population of modified cells in 14 days.…”