Fig. 4: Mvp1 Mut1 is defective in membrane binding and remodeling in vitro.

a Comparison of liposome binding by Mvp1 and Mvp1 Mut1. Protein (1.2 μM) was incubated without or with DOPS (PS) or DOPS + 5% PI3P (PS/PI3P) liposomes for 30 min at 21 °C prior to sedimentation. A representative result is shown. P pellet, S supernatant. Positions of molecular weight markers are shown to the left of the gels. b Quantification of the results presented in a. Individual data points and mean ± s.d. are shown. n = 9 for Mvp1 and 3 for Mvp1 Mut1. A 3 × 2 factorial ANOVA was conducted to determine the effects of the mutation (Mvp1 or Mvp1 Mut1) or the absence or presence of liposomes on the % sedimentation of protein. There was a significant interaction term (P = 0.0001) and both effects of liposome and Mvp1 or Mvp1 Mut1 were also significant (P < 0.0001 and P = 0.0002). A selected pair of values significant (Tukey HSD) at the 1% level is shown (**). Please note that the same data set for Mvp1 was used to compare with Mvp1 Mut1 here as was used to compare the different Mvp1 purification protocols presented in Supplementary Fig. 2b. For a and b, source data are provided as a Source Data file. c Mvp1 Mut1 is unable to tubulate PS liposomes containing 5% PI3P. Representative micrographs of negative-stained liposomes incubated either with Mvp1 or with Mvp1 Mut1 are shown. Scale bar—200 nm. d Mvp1 Mut1 is dimeric. Representative cryo-EM 3d class average of Mvp1 Mut1, with an approximate resolution of 8 Å. e Unassigned density. The D2-symmetrized, sharpened map, at contour level 4σ, is colored according to distance from the atomic model of the Mvp1 tetramer: color is assigned if the density is within 3 Å of the atomic model. The unassigned density is therefore shown in gray. f Model of membrane remodeling by Mvp1.