title: Chemical cross-linking/mass spectrometry maps the amyloid β peptide binding region on both apolipoprotein E domains.
abstract: Apolipoprotein E (apoE) binds the amyloid β peptide (Aβ), one of the major culprits in Alzheimer's disease development. The formation of apoE:Aβ complexes is implicated in both Aβ clearance and fibrillization. However, the binding interface between apoE and Aβ is poorly defined despite substantial previous research efforts, and the exact role of apoE in the pathology of Alzheimer's disease remains largely elusive. Here, we compared the three main isoforms of apoE (E2, E3, and E4) for their interaction with Aβ1-42 in an early stage of aggregation and at near physiological conditions. Using electron microscopy and Western blots, we showed that all three isoforms are able to prevent Aβ fibrillization and form a noncovalent complex, with one molecule of Aβ bound per apoE. Using chemical cross-linking coupled to mass spectrometry, we further examined the interface of interaction between apoE2/3/4 and Aβ. Multiple high-confidence intermolecular apoE2/3/4:Aβ cross-links confirmed that Lys16 is located in the region of Aβ binding to apoE2/3/4. Further, we demonstrated that both N- and C-terminal domains of apoE2/3/4 are interacting with Aβ. The cross-linked sites were mapped onto and evaluated in light of a recent structure of apoE. Our results support binding of the hydrophobic Aβ at the apoE domain-domain interaction interface, which would explain how apoE is able to stabilize Aβ and thereby prevent its subsequent aggregation.
authors.affiliation: †Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Deroo
authors.affiliation: ‡Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Stengel
authors.affiliation: †Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Mohammadi
authors.affiliation: †Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Henry
authors.affiliation: ∥Nanobiophysics Group, MIRA Institute for Biomedical Technology and Technical Medicine, Faculty of Science and Technology, University of Twente, Enschede, The Netherlands.|⊥Structural Biology Brussels, Department of Biotechnology, and Structural Biology Research Center, VIB, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Ellen
authors.initials: E
authors.lastname: Hubin
authors.affiliation: †Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Krammer
authors.affiliation: ‡Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland.|§Faculty of Science, University of Zurich, Zurich, Switzerland.
authors.forename: Ruedi
authors.initials: R
authors.lastname: Aebersold
authors.affiliation: †Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Vincent
authors.initials: V
authors.lastname: Raussens
mesh_terms: D016229:Amyloid beta-Peptides / Q000378:metabolism*; D053329:Apolipoprotein E2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D053318:Apolipoprotein E3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D053327:Apolipoprotein E4 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001057:Apolipoproteins E / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D003432:Cross-Linking Reagents / Q000737:chemistry; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008239:Lysine / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D010446:Peptide Fragments / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D053719:Tandem Mass Spectrometry
chemical_list: D016229:Amyloid beta-Peptides; D053329:Apolipoprotein E2; D053318:Apolipoprotein E3; D053327:Apolipoprotein E4; D001057:Apolipoproteins E; D003432:Cross-Linking Reagents; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D008239:Lysine