Fig. 1: Mvp1 tetramerization is dependent on its N-terminus.

a Mvp1 deforms PS liposomes containing 5% PI3P into irregular tubes. Representative micrographs of negative-stained liposomes incubated either with buffer (control) or with Mvp1. Scale bar—200 nm. b Mvp1 is a tetramer. The absolute molecular weight of Mvp1 was determined using SEC-MALS. The molecular weight, shown in magenta or teal across the elution peaks, are plotted on the right-hand axis. Theoretical molecular weights of Mvp1 dimers and tetramers, calculated according to the Mvp1 sequence, are shown as dotted gray lines. The differential refractive index of the elutions are plotted on the left-hand axis. Mvp1 was eluted in buffer containing either 150 mM (magenta) or 250 mM (teal) NaCl. c As in b, Mvp1 Δ2-100 was eluted in buffer containing 250 mM NaCl. d Comparison of liposome binding by Mvp1 and Mvp1 Δ2-100. 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. Shown is a representative result. P pellet, S supernatant. Positions of molecular weight markers are shown to the left of the gels. e Quantification of the results presented in d. Individual data points and mean ± s.d. are shown. n = 3 for Mvp1 and 4 for Mvp1 Δ2-100. A 3 × 2 factorial ANOVA was conducted to determine the effects of N-terminus (Mvp1 or Mvp1 Δ2-100) or the absence or presence of liposomes on the % sedimentation of protein. There was a significant interaction term (P < 0.0001) and each main effect was also significant (P < 0.0001). Selected pairs of values significant (Tukey HSD) at the 1% level are shown (**). For d and e, source data are provided as a Source Data file. f As in a but with Mvp1 Δ2-100. The inset shows an example of a rare subpopulation of highly twisted tubes observed only when PS/PI3P liposomes were incubated with Mvp1 Δ2-100. Scale bars—200 nm.