Integrative Study of the Structural and Dynamical Properties of a KirBac3.1 Mutant: Functional Implication of a Highly Conserved Tryptophan in the Transmembrane Domain.
Charline FagnenLudovic BannwarthIman OubellaDania ZunigaAhmed HaouzEric ForestRosa ScalaSaïd BendahhouRita De ZorziDavid PerahiaCatherine Vénien-BryanPublished in: International journal of molecular sciences (2021)
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.
Keyphrases
- wild type
- blood glucose
- induced apoptosis
- amino acid
- transcription factor
- cell cycle arrest
- glycemic control
- density functional theory
- type diabetes
- mass spectrometry
- metabolic syndrome
- oxidative stress
- signaling pathway
- endoplasmic reticulum stress
- adipose tissue
- white matter
- blood brain barrier
- high speed
- subarachnoid hemorrhage
- weight loss