title: Novel zinc-binding site in the E2 domain regulates amyloid precursor-like protein 1 (APLP1) oligomerization.
abstract: The amyloid precursor protein (APP) and the APP-like proteins 1 and 2 (APLP1 and APLP2) are a family of multidomain transmembrane proteins possessing homo- and heterotypic contact sites in their ectodomains. We previously reported that divalent metal ions dictate the conformation of the extracellular APP E2 domain (Dahms, S. O., Könnig, I., Roeser, D., Gührs, K.-H., Mayer, M. C., Kaden, D., Multhaup, G., and Than, M. E. (2012) J. Mol. Biol. 416, 438-452), but unresolved is the nature and functional importance of metal ion binding to APLP1 and APLP2. We found here that zinc ions bound to APP and APLP1 E2 domains and mediated their oligomerization, whereas the APLP2 E2 domain interacted more weakly with zinc possessing a less surface-exposed zinc-binding site, and stayed monomeric. Copper ions bound to E2 domains of all three proteins. Fluorescence resonance energy transfer (FRET) analyses examined the effect of metal ion binding to APP and APLPs in the cellular context in real time. Zinc ions specifically induced APP and APLP1 oligomerization and forced APLP1 into multimeric clusters at the plasma membrane consistent with zinc concentrations in the blood and brain. The observed effects were mediated by a novel zinc-binding site within the APLP1 E2 domain as APLP1 deletion mutants revealed. Based upon its cellular localization and its dominant response to zinc ions, APLP1 is mainly affected by extracellular zinc among the APP family proteins. We conclude that zinc binding and APP/APLP oligomerization are intimately linked, and we propose that this represents a novel mechanism for regulating APP/APLP protein function at the molecular level.
authors.affiliation: From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany.
authors.forename: Magnus C
authors.initials: MC
authors.lastname: Mayer
authors.affiliation: From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Kaden
authors.affiliation: From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany.
authors.forename: Linda
authors.initials: L
authors.lastname: Schauenburg
authors.affiliation: the Department of Pharmacology and Therapeutics, McGill University Montreal, Montreal, Quebec H3G 1Y6, Canada.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Hancock
authors.affiliation: the Molekulare Pharmakologie und Zellbiologie, Thielallee 67-73, Neurowissenschaftliches Forschungszentrum, Charité-Universitätsmedizin Berlin, 14195 Berlin, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Voigt
authors.affiliation: the Leibniz Institute for Age Research, Protein Crystallography Group, Fritz Lipmann Institute, Beutenbergstrasse 11, 07745 Jena, Germany, and.
authors.forename: Dirk
authors.initials: D
authors.lastname: Roeser
authors.affiliation: the Department of Pharmacology and Therapeutics, McGill University Montreal, Montreal, Quebec H3G 1Y6, Canada.
authors.forename: Christian
authors.initials: C
authors.lastname: Barucker
authors.affiliation: the Leibniz Institute for Age Research, Protein Crystallography Group, Fritz Lipmann Institute, Beutenbergstrasse 11, 07745 Jena, Germany, and.
authors.forename: Manuel E
authors.initials: ME
authors.lastname: Than
authors.affiliation: the Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Medizinische Fakultät der Universität Leipzig, Härtelstrasse 16-18, 04107 Leipzig, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schaefer
authors.affiliation: From the Institut für Chemie und Biochemie, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany, the Department of Pharmacology and Therapeutics, McGill University Montreal, Montreal, Quebec H3G 1Y6, Canada, gerhard.multhaup@mcgill.ca.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Multhaup
mesh_terms: D000595:Amino Acid Sequence; D016564:Amyloid beta-Protein Precursor / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D003300:Copper / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D055503:Protein Multimerization / Q000187:drug effects; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D015032:Zinc / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D016564:Amyloid beta-Protein Precursor; D003300:Copper; D015032:Zinc
keywords: Amyloid Precursor Protein (APP); Fluorescence Resonance Energy Transfer (FRET); Mass Spectrometry (MS); Metalloprotein; Zinc