title: The ESCRT-III adaptor protein Bro1 controls functions of regulator for free ubiquitin chains 1 (Rfu1) in ubiquitin homeostasis.
abstract: Yeast Rfu1 (regulator for free ubiquitin chain 1) localizes to endosomes and plays a role in ubiquitin homeostasis by inhibiting the activity of Doa4. We show that Bro1, a member of the class E vacuolar protein sorting proteins that recruits Doa4 to endosomes and stimulates Doa4 deubiquitinating activity, also recruits Rfu1 to endosomes for involvement in ubiquitin homeostasis. This recruitment was mediated by the direct interaction between a region containing the YPEL motif in Rfu1 and the V domain in Bro1, which could be analogous to the interaction between the mammalian Alix V domain and YPXnL motifs of viral and cellular proteins. Furthermore, overexpression of Bro1, particularly the V domain, prevented Rfu1 degradation in response to heat shock. Thus, Bro1, a Doa4 positive regulator, regulated Rfu1, a negative regulator of Doa4. Rfu1 degradation partly involved the proteasome and a ubiquitin ligase Rsp5, suggesting that Rfu1 stability was regulated by ubiquitin-proteasome pathways.
authors: From the Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 113-8613 and the Department of Applied Biological Chemistry, Graduate School of Agriculture, Shizuoka University, Shizuoka 422-8529, Japan kimura.yoko@shizuoka.ac.jp.
authors: Yoko
authors: Y
authors: Kimura
authors: From the Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 113-8613 and.
authors: Junko
authors: J
authors: Kawawaki
authors: From the Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 113-8613 and.
authors: Yukie
authors: Y
authors: Kakiyama
authors: From the Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 113-8613 and.
authors: Ayumi
authors: A
authors: Shimoda
authors: From the Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 113-8613 and.
authors: Keiji
authors: K
authors: Tanaka
mesh_terms: D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism* / Q000502:physiology; D006706:Homeostasis; D059748:Proteolysis; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism* / Q000502:physiology*; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: C480237:Bro1 protein, S cerevisiae; D056827:Endosomal Sorting Complexes Required for Transport; C542553:Rfu1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin
keywords: Cell Biology; Deubiquitination; Endosome; Heat Shock; Protein Degradation; Stress Response; Ubiquitin; Ubiquitin Ligase