title: The Phe105 loop of Alix Bro1 domain plays a key role in HIV-1 release.
abstract: Alix and cellular paralogs HD-PTP and Brox contain N-terminal Bro1 domains that bind ESCRT-III CHMP4. In contrast to HD-PTP and Brox, expression of the Bro1 domain of Alix alleviates HIV-1 release defects that result from interrupted access to ESCRT. In an attempt to elucidate this functional discrepancy, we solved the crystal structures of the Bro1 domains of HD-PTP and Brox. They revealed typical "boomerang" folds they share with the Bro1 Alix domain. However, they each contain unique structural features that may be relevant to their specific function(s). In particular, phenylalanine residue in position 105 (Phe105) of Alix belongs to a long loop that is unique to its Bro1 domain. Concurrently, mutation of Phe105 and surrounding residues at the tip of the loop compromise the function of Alix in HIV-1 budding without affecting its interactions with Gag or CHMP4. These studies identify a new functional determinant in the Bro1 domain of Alix.
authors: Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors: Paola
authors: P
authors: Sette
authors: Ruiling
authors: R
authors: Mu
authors: Vincent
authors: V
authors: Dussupt
authors: Jiansheng
authors: J
authors: Jiang
authors: Greg
authors: G
authors: Snyder
authors: Patrick
authors: P
authors: Smith
authors: Tsan Sam
authors: TS
authors: Xiao
authors: Fadila
authors: F
authors: Bouamr
mesh_terms: D002135:Calcium-Binding Proteins / Q000737:chemistry*; D018797:Cell Cycle Proteins / Q000737:chemistry*; D003001:Cloning, Molecular; D056827:Endosomal Sorting Complexes Required for Transport / Q000737:chemistry* / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D015497:HIV-1 / Q000737:chemistry* / Q000502:physiology; D006801:Humans; D047468:Immunoprecipitation; D016297:Mutagenesis, Site-Directed; D010649:Phenylalanine / Q000737:chemistry*; D017510:Protein Folding; D025941:Protein Interaction Mapping; D017433:Protein Structure, Secondary; D054558:Protein Tyrosine Phosphatases, Non-Receptor / Q000737:chemistry / Q000502:physiology; D013329:Structure-Activity Relationship; D014162:Transfection; D057074:Virus Release
chemical_list: C529397:BROX protein, human; C478397:CHMP4B protein, human; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C117020:PDCD6IP protein, human; D010649:Phenylalanine; C114102:PTPN23 protein, human; D054558:Protein Tyrosine Phosphatases, Non-Receptor