Combination of fluorescence techniques and molecular docking was used to monitor interaction of Na,K-ATPase and its large cytoplasmic loop connecting fourth and fifth transmembrane helices (C45) with fluorone dyes (i.e. eosin Y, 5(6)-carboxyeosin, rose bengal, fluorescein, and erythrosine B). Our data suggested that there are at least two binding sites for all used fluorone dyes, except of 5(6)-carboxyeosin. The first binding site is located on C45 loop, and it is sensitive to the presence of nucleotide. The other site is located on the extracellular part of the enzyme, and it is sensitive to the presence of Na(+) or K(+) ions. The molecular docking revealed that in the open conformation of C45 loop (which is obtained in the presence of ATP) all used fluorone dyes occupy position directly inside the ATP-binding pocket, while in the closed conformation (i.e. in the absence of any ligand) they are located only near the ATP-binding site depending on their different sizes. On the extracellular part of the protein, the molecular docking predicts two possible binding sites with similar binding energy near Asp897(α) or Gln69(β). The former was identified as a part of interaction site between α- and β-subunits, the latter is in contact with conserved FXYD sequence of the γ-subunit. Our findings provide structural explanation for numerous older studies, which were performed with fluorone dyes before the high-resolution structures were known. Further, fluorone dyes seem to be good probes for monitoring of intersubunit interactions influenced by Na(+) and K(+) binding.
- MeSH
- Adenosine Triphosphate chemistry MeSH
- Rose Bengal chemistry MeSH
- Models, Chemical MeSH
- Cytoplasm metabolism MeSH
- Potassium chemistry MeSH
- Eosine Yellowish-(YS) chemistry MeSH
- Erythrosine chemistry MeSH
- Escherichia coli metabolism MeSH
- Fluorescein chemistry MeSH
- Fluoresceins chemistry pharmacology MeSH
- Fluorescent Dyes pharmacology MeSH
- Protein Conformation MeSH
- Humans MeSH
- Molecular Conformation MeSH
- Sodium chemistry MeSH
- Sodium-Potassium-Exchanging ATPase chemistry MeSH
- Protein Structure, Tertiary MeSH
- Binding Sites MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
