FIGURE 3.
MxA binds to and tubulates liposomes by forming highly ordered arrays. A and B, sedimentation of MxA during high speed centrifugation. MxA (180 μg/ml) was diluted in HCB with the salt concentrations indicated in the absence (A) or presence (B) of TBL liposomes (1 mg/ml total brain lipids) and incubated for 20 min at 20 °C. The mixtures were separated into supernatant (S) and pellet (P) fractions by ultracentrifugation at 100,000 × g and analyzed by SDS-PAGE and Coomassie staining. The graph presents quantification of the stained protein bands of three independent experiments. Error bars, S.D. C, negative stain (a and b) and cryo-TEM images (c–e) of MxA helical arrays around liposome tubes and (f) cryo-TEM image of a dynamin-lipid tube. MxA (a–e, 250 μg/ml) or dynamin (f, 250 μg/ml) were incubated in HCB100 or HCB300 (e) for 3 h at 25 °C in the presence of liposomes generated from TBL (a–c, 500 μg/ml) or PS (d–f, 500 μg/ml). Scale bars, 100 nm (a and b) and 50 nm (c–f).