2. Academic Validation
  3. APH1 polar transmembrane residues regulate the assembly and activity of presenilin complexes

APH1 polar transmembrane residues regulate the assembly and activity of presenilin complexes

  • J Biol Chem. 2009 Jun 12;284(24):16298-16307. doi: 10.1074/jbc.M109.000067.
Raphaëlle Pardossi-Piquard 1,  Seung-Pil Yang 1,  Soshi Kanemoto 1,  Yongjun Gu 1,  Fusheng Chen 1,  Christopher Böhm 1,  Jean Sevalle 2,  Tong Li 3,  Philip C Wong 3,  Frédéric Checler 2,  Gerold Schmitt-Ulms 4,  Peter St George-Hyslop 5,  Paul E Fraser 6
Affiliations

Affiliations

  • 1 From the Centre for Research in Neurodegenerative Diseases, Toronto, Ontario M5S 3H2, Canada.
  • 2 Institut de Pharmacologie Moléculaire et Cellulaire and Institut de NeuroMédecine Moléculaire of CNRS, Equipe Labellisée Fondation pour la Recherche Médicale, Valbonne 06560, France.
  • 3 Departments of Neuroscience and Pathology, John Hopkins University School of Medicine, Baltimore, Maryland 21205.
  • 4 From the Centre for Research in Neurodegenerative Diseases, Toronto, Ontario M5S 3H2, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario M5G 1L5, Canada.
  • 5 From the Centre for Research in Neurodegenerative Diseases, Toronto, Ontario M5S 3H2, Canada; Department of Medicine (Division of Neurology), Toronto Western Hospital Research Institute, University Health Network, Toronto, Ontario M5T 2S8, Canada; Department of Clinical Neuroscience, University of Cambridge, Cambridge CB2 OXY, United Kingdom.
  • 6 From the Centre for Research in Neurodegenerative Diseases, Toronto, Ontario M5S 3H2, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada. Electronic address: paul.fraser@utoronto.ca.
PMID: 19369254 DOI: 10.1074/jbc.M109.000067
Abstract

Complexes involved in the gamma/epsilon-secretase-regulated intramembranous proteolysis of substrates such as the amyloid-beta precursor protein are composed primarily of presenilin (PS1 or PS2), nicastrin, anterior pharynx defective-1 (APH1), and PEN2. The presenilin aspartyl residues form the catalytic site, and similar potentially functional polar transmembrane residues in APH1 have been identified. Substitution of charged (E84A, R87A) or polar (Q83A) residues in TM3 had no effect on complex assembly or activity. In contrast, changes to either of two highly conserved histidines (H171A, H197A) located in TM5 and TM6 negatively affected PS1 cleavage and altered binding to Other secretase components, resulting in decreased amyloid generating activity. Charge replacement with His-to-Lys substitutions rescued nicastrin maturation and PS1 endoproteolysis leading to assembly of the formation of structurally normal but proteolytically inactive gamma-secretase complexes. Substitution with a negatively charged side chain (His-to-Asp) or altering the structural location of the histidines also disrupted gamma-secretase binding and abolished functionality of APH1. These results suggest that the conserved transmembrane histidine residues contribute to APH1 function and can affect presenilin catalytic activity.

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