title: Conformational Changes in the Endosomal Sorting Complex Required for the Transport III Subunit Ist1 Lead to Distinct Modes of ATPase Vps4 Regulation.
abstract: Intralumenal vesicle formation of the multivesicular body is a critical step in the delivery of endocytic cargoes to the lysosome for degradation. Endosomal sorting complex required for transport III (ESCRT-III) subunits polymerize on endosomal membranes to facilitate membrane budding away from the cytoplasm to generate these intralumenal vesicles. The ATPase Vps4 remodels and disassembles ESCRT-III, but the manner in which Vps4 activity is coordinated with ESCRT-III function remains unclear. Ist1 is structurally homologous to ESCRT-III subunits and has been reported to inhibit Vps4 function despite the presence of a microtubule-interacting and trafficking domain-interacting motif (MIM) capable of stimulating Vps4 in the context of other ESCRT-III subunits. Here we report that Ist1 inhibition of Vps4 ATPase activity involves two elements in Ist1: the MIM itself and a surface containing a conserved ELYC sequence. In contrast, the MIM interaction, in concert with a more open conformation of the Ist1 core, resulted in stimulation of Vps4. Addition of the ESCRT-III subunit binding partner of Ist1, Did2, also converted Ist1 from an inhibitor to a stimulator of Vps4 ATPase activity. Finally, distinct regulation of Vps4 by Ist1 corresponded with altered ESCRT-III disassembly in vitro. Together, these data support a model in which Ist1-Did2 interactions during ESCRT-III polymerization coordinate Vps4 activity with the timing of ESCRT-III disassembly.
authors.affiliation: From the Biochemistry and Molecular Biology Department, Mayo Graduate School, and.
authors.forename: Jason
authors.initials: J
authors.lastname: Tan
authors.affiliation: From the Biochemistry and Molecular Biology Department.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Davies
authors.affiliation: From the Biochemistry and Molecular Biology Department.
authors.forename: Johanna A
authors.initials: JA
authors.lastname: Payne
authors.affiliation: Mayo Medical Genome Facility Proteomics Core, Mayo Clinic, Rochester, Minnesota 55905.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Benson
authors.affiliation: From the Biochemistry and Molecular Biology Department, katzmann.david@mayo.edu.
authors.forename: David J
authors.initials: DJ
authors.lastname: Katzmann
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D017510:Protein Folding; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; C532818:Ist1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C107528:VPS4 protein, S cerevisiae; D033921:Vesicular Transport Proteins; D000251:Adenosine Triphosphatases
keywords: ATPase; Did2; Ist1; Vps4; endosomal sorting; endosomal sorting complexes required for transport (ESCRT); protein conformation; protein sorting; protein stability