Fig. 5: Myo6 can form an antiparallel dimer through residues 875–940 which allow large steps.
From: How myosin VI traps its off-state, is activated and dimerizes
a (Left) X-ray structure of mouse Myo6 875–940 antiparallel dimer colored according to B-factor from 18.6 Å2 (dark blue) to 150.8 Å2 (red). (Right) Key residues for dimer stabilization. Apolar contacts are mediated by residues pictured in green. Dotted blue line: polar contacts. Residues mutated in our triple mutant (T888D.R892E.V903D) are underlined. b Close-up of the dimerization interface of Myo6 875–940 in the electronic density. c Triple helix bundle (PDB: 2LD3) domain. T888, R892, V903, T845C and A880C pictured as sticks are surface residues. d SEC-MALS profiles of Myo6 875–940 WT (red) and T888D.R892E.V903D mutant (blue), following injection of 50 μL at 10 mg/mL in 10 mM Tris-HCl pH 7.5; 50 mM NaCl; 5 mM NaN3; 0.5 mM TCEP. Thin lines: static light scattering; thick lines: measured molecular mass. WT elutes as dimers (32 μM concentration at the peak, measured by the in-line refractometer) and T888D.R892E.V903D mutant elutes as monomers (43 μM at the peak). e Model of active FLMyo6 dimer (see “Methods”). f ATPase rates (mean ± SD) of FLMyo6 WT (green), T888D.Q892E.V903D (gray), SAHmimic (blue) and L926Q (yellow) at 40 µM F-actin and increasing concentrations of GIPC1 (n = 6). ATPase rates of MDIns2 and zippered dimer11 without partner (n = 6) plotted as purple and red thick lines (respectively) as references for monomeric and dimeric Myo6. g Fluorescence intensity of internalized transferrin was measured for each condition after treatment with genistein (cells examined over 2 independent experiments: WT = 62, KO = 58, KO+ FLMyo6 (WT) = 79, KO+ FLMyo6 (T888D.R892E.V903D) = 66) (p < 0.001, one-way ANOVA; Tukey post-hoc comparisons; one-sided). P-values are the following: WT vs KO: p < 0.0001, WT vs KO+ FLMyo6 (WT): p = 0.3363, WT vs KO+ FLMyo6 (T888D.R892E.V903D): p < 0.0001 (***), KO vs KO+ FLMyo6 (WT): p = 0.0001, KO vs KO+ FLMyo6 (T888D.R892E.V903D): p = 0.5228, KO+ FLMyo6 (WT) vs KO+ FLMyo6 (T888D.R892E.V903D): p = 0.0146 ($).Whisker boxes (10–90 percentile with 2nd and 3rd quartiles within the box; white dot indicates the median) encased within a violin plot (generated with BoxPlotR70). (d, f, g) Source data are provided as a Source Data file.
