title: Intracellularly inducible, ubiquitin hydrolase-insensitive tandem ubiquitins inhibit the 26S proteasome activity and cell division.
abstract: We constructed polyubiquitin derivatives that contain a tandem repeat of ubiquitins and were insensitive to ubiquitin hydrolases. They were designated tandem ubiquitin (tUb) with the number of repeats, such as tUb2. When tUbs were expressed under the control of the GAL1 promoter in the wild-type yeast strain, growth was strongly inhibited. Under these conditions, the degradation of N-end rule substrates, a UFD substrate and Gcn4 was inhibited, indicating that the tUb inhibits 26S proteasome activity. Consistent with this, tUb binds to the 26S proteasome. We showed that tUb inhibited the in vitro degradation of polyubiquitinylated Sic1 by the 26S proteasome. When tUB6 messenger RNA was injected into Xenopus embryos, cell division was inhibited, suggesting that tUb can be used as a versatile inhibitor of the 26S proteasome.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo, Tokyo 113-0033, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Saeki
authors.forename: Erika
authors.initials: E
authors.lastname: Isono
authors.forename: Tomoko
authors.initials: T
authors.lastname: Oguchi
authors.forename: Masumi
authors.initials: M
authors.lastname: Shimada
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sone
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kawahara
authors.forename: Hideyoshi
authors.initials: H
authors.lastname: Yokosawa
authors.forename: Akio
authors.initials: A
authors.lastname: Toh-e
mesh_terms: D002455:Cell Division / Q000502:physiology*; D002846:Chromatography, Affinity; D025821:Polyubiquitin / Q000096:biosynthesis / Q000235:genetics; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism*; D015003:Yeasts / Q000378:metabolism
chemical_list: D025801:Ubiquitin; D025821:Polyubiquitin; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease