Fig. 7: Orientation of the Vipp1 hairpin and sorted tomographic slices of Vipp1 membrane interactions.
From: Structural basis for Vipp1 membrane binding: from loose coats and carpets to ring and rod assemblies
a, Schematic view of Vipp1 α1–α3 hairpins relative to the membrane axis in stacked-ring assembly, type II tubes and type I tubes. b, The identified structures are sorted with regard to Vipp1 membrane interactions and the degree of membrane deformation. Initially, Vipp1 binds to free membranes (i). When the Vipp1 monomers reach a critical local concentration on the membrane surface (ii), they start to oligomerize and form a membrane bulge (iii). Vipp1 induces membrane curvature upon oligomerization (iv). The induced curvature can result in the formation of a budding Vipp1 oligomer with enclosed membrane (v). This assembly can either bud off the membrane to produce rings (vi) or grows further to extended rod structures (vii–x). The rods can reside at the host membrane or bud off to produce Vipp1-coated membrane tubes. The budded rings can fuse to form stacked rings that finally relax to Vipp1-coated membrane tubes. Please note that this model is limited by the observation of Vipp1 assemblies in micrographs and sorting them into logical sequence.
