The dynamic interplay of PIP2 and ATP in the regulation of the KATP channel

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.

Simulating PIP2-induced gating transitions in Kir6.2 channels

“…When comparing residues that render the PIP 2 -binding site in 6C3O and 6C3P, a critical difference becomes apparent. R176 was determined to be a key residue for PIP 2 -dependent activation in Kir6.2 (Baukrowitz et al 1998; Fan and Makielski 1997; Haider et al 2007; Pipatpolkai et al 2020, 2021; Shyng et al 2000) and other Kir families (Lacin et al 2017; C. H. Lee et al 2016; Lopes et al 2002; Soom et al 2001; Xie et al 2005).…”