title: Double-sided ubiquitin binding of Hrs-UIM in endosomal protein sorting.
abstract: Hrs has an essential role in sorting of monoubiquitinated receptors to multivesicular bodies for lysosomal degradation, through recognition of ubiquitinated receptors by its ubiquitin-interacting motif (UIM). Here, we present the structure of a complex of Hrs-UIM and ubiquitin at 1.7-A resolution. Hrs-UIM forms a single alpha-helix, which binds two ubiquitin molecules, one on either side. These two ubiquitin molecules are related by pseudo two-fold screw symmetry along the helical axis of the UIM, corresponding to a shift by two residues on the UIM helix. Both ubiquitin molecules interact with the UIM in the same manner, using the Ile44 surface, with equal binding affinities. Mutational experiments show that both binding sites of Hrs-UIM are required for efficient degradative protein sorting. Hrs-UIM belongs to a new subclass of double-sided UIMs, in contrast to its yeast homolog Vps27p, which has two tandem single-sided UIMs.
authors.affiliation: Structural Biology Research Center, Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hirano
authors.forename: Masato
authors.initials: M
authors.lastname: Kawasaki
authors.forename: Hideaki
authors.initials: H
authors.lastname: Ura
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Kato
authors.forename: Camilla
authors.initials: C
authors.lastname: Raiborg
authors.forename: Harald
authors.initials: H
authors.lastname: Stenmark
authors.forename: Soichi
authors.initials: S
authors.lastname: Wakatsuki
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002417:Cattle; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D021381:Protein Transport; D020349:Surface Plasmon Resonance; D025801:Ubiquitin / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D010750:Phosphoproteins; D025801:Ubiquitin; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate; D004815:Epidermal Growth Factor