title: Pen-2 is incorporated into the gamma-secretase complex through binding to transmembrane domain 4 of presenilin 1.
abstract: gamma-Secretase is a multimeric membrane protein complex comprised of presenilin (PS), nicastrin (Nct), Aph-1, and Pen-2. It is a member of an atypical class of aspartic proteases that hydrolyzes peptide bonds within the membrane. During the biosynthetic process of the gamma-secretase complex, Nct and Aph-1 form a heterodimeric intermediate complex and bind to the C-terminal region of PS, serving as a stabilizing scaffold for the complex. Pen-2 is then recruited into this trimeric complex and triggers endoproteolysis of PS, conferring gamma-secretase activity. Although the Pen-2 accumulation depends on PS, the binding partner of Pen-2 within the gamma-secretase complex remains unknown. We reconstituted PS1 in Psen1/Psen2 deficient cells by expressing a series of PS1 mutants in which one of the N-terminal six transmembrane domains (TMDs) was swapped with those of CD4 (a type I transmembrane protein) or CLAC-P (a type II transmembrane protein). We report that the proximal two-thirds of TMD4 of PS1, including the conserved Trp-Asn-Phe sequence, are required for its interaction with Pen-2. Using a chimeric CD4 molecule harboring PS1 TMD4, we further demonstrate that the PS1 TMD4 bears a direct binding motif to Pen-2. Pen-2 may contribute to the activation of the gamma-secretase complex by directly binding to the TMD4 of PS1.
authors.affiliation: Department of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Watanabe
authors.forename: Taisuke
authors.initials: T
authors.lastname: Tomita
authors.forename: Chihiro
authors.initials: C
authors.lastname: Sato
authors.forename: Toshio
authors.initials: T
authors.lastname: Kitamura
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Morohashi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Iwatsubo
mesh_terms: D000595:Amino Acid Sequence; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids; D053764:Presenilin-1; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid
chemical_list: D008565:Membrane Proteins; C508853:PSEN1 protein, human; C469349:PSENEN protein, human; D053764:Presenilin-1; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human