Fig. 4: E1-HT membrane insertion and opposing membrane superposition (stages IV-VI).

a–d Annotated tomogram slices showing insertion of protein densities into the liposome (L) causing disruption of membrane density at the interface. CHIKV (V) are annotated similar to previous figures with red dotted rectangles enclosing interaction areas of interest. e Cartoon representation of fusion stage IV – E1-HT membrane insertion. Created with Biorender.com. f–h Tomogram slices showing superposition of the viral and liposome membranes. Interaction interfaces are enclosed in red rectangles. Variation and fluidity in the glycoprotein layer (orange triangles) can be seen in f, g. White triangles represent the gap observed between the NC and inner surface of the viral membrane (blue triangles). i Cartoon representation of fusion stage V—membrane superposition, with dotted rectangle outlining the interface. Created with Biorender.com. j, k Tomogram slices howing tightly docked membrane interfaces with the proximal leaflets too close to separate at the current tomogram resolution. Corresponding electron density plots along a line traversing the tight-membrane interface in the boxed region (red) of the tomogram slices are also shown. l. Cartoon representation of the tightly docked membrane interface (stage VI) with zoomed inset showing region of interest. Created with Biorender.com. Scale bar is 200 Å and black is high density in all panels.