Structure and membrane remodeling activity of ESCRT-III helical polymers

TLDR

ESCRTs mediate vesicle and virus budding by forming cytoplasm‑filled neck spirals that seal the budding site. ESCRT‑III and IST1 subunits assemble spirals on the outer surface of membrane tubules, enabling budding of tubules and vesicles into the cytosol. The study shows ESCRTs can also scission membrane tubules with the opposite topology, requiring only minor structural rearrangements to reverse function. McCullough et al., Science, p.

Abstract

ESCRTs work in two very different ways The so-called ESCRT proteins are involved in the budding of vesicles into the lumen of endosomes and in virus budding. These reactions involve the formation of a cytoplasm-filled neck that spirals of the ESCRTs help to seal. McCullough et al. now show that ESCRTs can also promote the scission of membrane tubules with the completely opposite topology. ESCRT-III and IST1 ESCRT subunits form spirals on the outside of membrane tubules and so can mediate the budding of tubules and vesicles into the cytosol. Relatively minor structural rearrangements were required to turn ESCRT function on its head. Science , this issue p. 1548