Integrative Study of the Structural and Dynamical Properties of a KirBac3.1 Mutant: Functional Implication of a Highly Conserved Tryptophan in the Transmembrane Domain

• Published in: International journal of molecular sciences Vol. 23; no. 1; p. 335
• Main Authors: Fagnen, Charline, Bannwarth, Ludovic, Oubella, Iman, Zuniga, Dania, Haouz, Ahmed, Forest, Eric, Scala, Rosa, Bendahhou, Saïd, De Zorzi, Rita, Perahia, David, Vénien-Bryan, Catherine
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.01.2022; MDPI
• Subjects: Amino Acid Sequence; Beta cells; Binding sites; Blood glucose; Channel gating; Channels; Chemical Sciences; Conserved Sequence; Crystal structure; crystal structure of KirBac3.1 W46R; Crystallography, X-Ray; Diabetes; Diabetes mellitus; electrophysiology; Flexibility; gain of function Kir; Glucose; HDX-mass spectrometry; Homology; Hydrogen Deuterium Exchange-Mass Spectrometry; Hypoglycemia; Insulin; Insulin secretion; Investigations; Ion Channel Gating; Life Sciences; molecular dynamics; Mutant Proteins - chemistry; Mutant Proteins - metabolism; Mutants; Mutation; Mutation - genetics; Neonates; normal modes; Organs; Pancreas; Potassium; Potassium channels (inwardly-rectifying); Potassium Channels, Inwardly Rectifying - chemistry; Potassium Channels, Inwardly Rectifying - genetics; Protein Domains; Protein Interaction Maps; Protein Structure, Secondary; Residues; Tryptophan; Tryptophan - chemistry; HDX-mass spectrometry; crystal structure of KirBac3.1 W46R; electrophysiology; neonatal diabetes mellitus; gain of function Kir; molecular dynamics; normal modes
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms23010335

ATP-sensitive potassium (K-ATP) channels are ubiquitously expressed on the plasma membrane of cells in several organs, including the heart, pancreas, and brain, and they govern a wide range of physiological processes. In pancreatic β-cells, K-ATP channels composed of Kir6.2 and SUR1 play a key role in coupling blood glucose and insulin secretion. A tryptophan residue located at the cytosolic end of the transmembrane helix is highly conserved in eukaryote and prokaryote Kir channels. Any mutation on this amino acid causes a gain of function and neonatal diabetes mellitus. In this study, we have investigated the effect of mutation on this highly conserved residue on a KirBac channel (prokaryotic homolog of mammalian Kir6.2). We provide the crystal structure of the mutant KirBac3.1 W46R (equivalent to W68R in Kir6.2) and its conformational flexibility properties using HDX-MS. In addition, the detailed dynamical view of the mutant during the gating was investigated using the in silico method. Finally, functional assays have been performed. A comparison of important structural determinants for the gating mechanism between the wild type KirBac and the mutant W46R suggests interesting structural and dynamical clues and a mechanism of action of the mutation that leads to the gain of function.