Fig. 2: HKI-N binding to membranes.
From: Hexokinase-I directly binds to a charged membrane-buried glutamate of mitochondrial VDAC1 and VDAC2
a Atomic model of HKI (PDB: 1BG3, cyan) with the N-terminal α-helix (HKI-N) highlighted in residue-type coloring. b HeliQuest analysis and VDW/Dynamic Bonds representation of the coarse-grained HKI-N backbone reveals an α-helix with a polar and apolar face. c Model predicting that the apolar face of HKI-N mediates membrane binding, with the first half of the α-helix protruding deeper into the membrane bilayer. d Membrane residence time analysis of HKI-N and HKI-NL7Q using CG-MD simulations. Helices were bound to OMM-mimicking membranes following the restraining protocol described in Methods. After lifting the restraints, the distance of the helix residue closest to the membrane’s top leaflet was measured, until it surpassed 1.4 nm. Stills show representative configurations from each condition. Plots represent the time progression of the helix-membrane distances for six independent replicas per condition, as overlaid semitransparent traces; vertical rises correspond to each trace’s membrane-leaving event, from which point that trace is no longer drawn. e Fluorescence images of WT HeLa cells expressing EGFP-tagged HKI or HKIL7Q (green), fixed and then stained with DAPI (blue) and an antibody against Tom20 (magenta). Line scans showing degree of overlap between HKI and Tom20 signals along the path of the arrow shown in the zoom-in. Scale bar, 10 μm. f Pearson’s correlation co-efficient analysis between HKI and Tom20 signals in cells as in (e). n = 20 (HKI) and 28 cells (HKIL7Q) over three independent experiments. p values were calculated by unpaired two-tailed t test.
