Abstract
E2-25K/Hip2 is an unusual ubiquitin-conjugating enzyme that interacts with the frameshift mutant of ubiquitin B (UBB(+1)) and has been identified as a crucial factor regulating amyloid-β neurotoxicity. To study the structural basis of the neurotoxicity mediated by the E2-25K-UBB(+1) interaction, we determined the three-dimensional structures of UBB(+1), E2-25K and the E2-25K/ubiquitin, and E2-25K/UBB(+1) complex. The structures revealed that ubiquitin or UBB(+1) is bound to E2-25K via the enzyme MGF motif and residues in α9 of the enzyme. Polyubiquitylation assays together with analyses of various E2-25K mutants showed that disrupting UBB(+1) binding markedly diminishes synthesis of neurotoxic UBB(+1)-anchored polyubiquitin. These results suggest that the interaction between E2-25K and UBB(+1) is critical for the synthesis and accumulation of UBB(+1)-anchored polyubiquitin, which results in proteasomal inhibition and neuronal cell death.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Binding Sites / genetics
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Cell Line, Tumor
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Cell Survival
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Crystallography, X-Ray
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Green Fluorescent Proteins / genetics
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Green Fluorescent Proteins / metabolism
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HEK293 Cells
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Humans
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Hydrogen Bonding
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Magnetic Resonance Spectroscopy
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Microscopy, Fluorescence
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Models, Molecular
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Molecular Sequence Data
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Multiprotein Complexes / chemistry
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Multiprotein Complexes / metabolism*
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Mutation
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Proteasome Endopeptidase Complex / metabolism*
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Protein Binding
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Protein Structure, Secondary
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Protein Structure, Tertiary
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Sequence Homology, Amino Acid
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Ubiquitin / chemistry
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Ubiquitin / genetics
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Ubiquitin / metabolism*
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Ubiquitin-Conjugating Enzymes / chemistry
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Ubiquitin-Conjugating Enzymes / genetics
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Ubiquitin-Conjugating Enzymes / metabolism*
Substances
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Multiprotein Complexes
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Recombinant Fusion Proteins
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UBB protein, human
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Ubiquitin
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Green Fluorescent Proteins
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UBE2K protein, human
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Ubiquitin-Conjugating Enzymes
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Proteasome Endopeptidase Complex
Associated data
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PDB/2KX0
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PDB/3K9O
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PDB/3K9P