title: Structural basis for endosomal targeting by the Bro1 domain.
abstract: Proteins delivered to the lysosome or the yeast vacuole via late endosomes are sorted by the ESCRT complexes and by associated proteins, including Alix and its yeast homolog Bro1. Alix, Bro1, and several other late endosomal proteins share a conserved 160 residue Bro1 domain whose boundaries, structure, and function have not been characterized. The crystal structure of the Bro1 domain of Bro1 reveals a folded core of 367 residues. The extended Bro1 domain is necessary and sufficient for binding to the ESCRT-III subunit Snf7 and for the recruitment of Bro1 to late endosomes. The structure resembles a boomerang with its concave face filled in and contains a triple tetratricopeptide repeat domain as a substructure. Snf7 binds to a conserved hydrophobic patch on Bro1 that is required for protein complex formation and for the protein-sorting function of Bro1. These results define a conserved mechanism whereby Bro1 domain-containing proteins are targeted to endosomes by Snf7 and its orthologs.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, Maryland 20892, USA.
authors.forename: Jaewon
authors.initials: J
authors.lastname: Kim
authors.forename: Sujatha
authors.initials: S
authors.lastname: Sitaraman
authors.forename: Aitor
authors.initials: A
authors.lastname: Hierro
authors.forename: Bridgette M
authors.initials: BM
authors.lastname: Beach
authors.forename: Greg
authors.initials: G
authors.lastname: Odorizzi
authors.forename: James H
authors.initials: JH
authors.lastname: Hurley
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray / Q000379:methods; D003593:Cytoplasm / Q000378:metabolism; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000378:metabolism*; D005455:Fluorescent Antibody Technique / Q000379:methods; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D066298:In Vitro Techniques; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000502:physiology; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D040681:Structural Homology, Protein; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: C480237:Bro1 protein, S cerevisiae; D056827:Endosomal Sorting Complexes Required for Transport; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D049452:Green Fluorescent Proteins