title: Structure of cellular ESCRT-III spirals and their relationship to HIV budding.
abstract: The ESCRT machinery along with the AAA+ ATPase Vps4 drive membrane scission for trafficking into multivesicular bodies in the endocytic pathway and for the topologically related processes of viral budding and cytokinesis, but how they accomplish this remains unclear. Using deep-etch electron microscopy, we find that endogenous ESCRT-III filaments stabilized by depleting cells of Vps4 create uniform membrane-deforming conical spirals which are assemblies of specific ESCRT-III heteropolymers. To explore functional roles for ESCRT-III filaments, we examine HIV-1 Gag-mediated budding of virus-like particles and find that depleting Vps4 traps ESCRT-III filaments around nascent Gag assemblies. Interpolating between the observed structures suggests a new role for Vps4 in separating ESCRT-III from Gag or other cargo to allow centripetal growth of a neck constricting ESCRT-III spiral.
authors.affiliation: Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States.
authors.forename: Anil G
authors.initials: AG
authors.lastname: Cashikar
authors.affiliation: Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States.
authors.forename: Soomin
authors.initials: S
authors.lastname: Shim
authors.affiliation: Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States.
authors.forename: Robyn
authors.initials: R
authors.lastname: Roth
authors.affiliation: Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Maldazys
authors.affiliation: Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States.
authors.forename: John E
authors.initials: JE
authors.lastname: Heuser
authors.affiliation: Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States.
authors.forename: Phyllis I
authors.initials: PI
authors.lastname: Hanson
mesh_terms: D000818:Animals; D001692:Biological Transport; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D048749:Cytokinesis; D003593:Cytoplasm / Q000378:metabolism; D056827:Endosomal Sorting Complexes Required for Transport / Q000737:chemistry*; D015683:Gene Products, gag / Q000737:chemistry; D057809:HEK293 Cells; D015497:HIV-1 / Q000737:chemistry / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D011108:Polymers / Q000737:chemistry; D011487:Protein Conformation; D057074:Virus Release
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D015683:Gene Products, gag; D011108:Polymers
keywords: ESCRT; HIV-1 budding; cell biology; deep-etch EM; endosome; human; multivesicular body; viruses