The dynamic interplay of PIP₂and ATP in the regulation of the K_ATPchannel

Abstract

ATP-sensitive potassium (KATP) channels couple the intracellular ATP concentration to insulin secretion. KATP channel activity is inhibited by ATP binding to the Kir6.2 tetramer and activated by phosphatidylinositol-4,5-bisphosphate (PIP2). Here, we use molecular dynamics (MD) simulation, electrophysiology and fluorescence spectroscopy to show that ATP and PIP2 occupy different binding pockets that share a single amino acid residue, K39. When both ligands are present, K39 shows a greater preference to co-ordinate with PIP2 than ATP. A neonatal diabetes mutation at K39 (K39R) increases the number of hydrogen bonds formed between K39 and PIP2, reducing ATP inhibition. We also find direct effects on nucleotide binding from mutating E179, a residue proposed to interact with PIP2. Our work suggests PIP2 and ATP interact allosterically to regulate KATP channel activity.