title: Lysine 624 of the amyloid precursor protein (APP) is a critical determinant of amyloid β peptide length: support for a sequential model of γ-secretase intramembrane proteolysis and regulation by the amyloid β precursor protein (APP) juxtamembrane region.
abstract: γ-Secretase is a multiprotein intramembrane cleaving aspartyl protease (I-CLiP) that catalyzes the final cleavage of the amyloid β precursor protein (APP) to release the amyloid β peptide (Aβ). Aβ is the primary component of senile plaques in Alzheimer's disease (AD), and its mechanism of production has been studied intensely. γ-Secretase executes multiple cleavages within the transmembrane domain of APP, with cleavages producing Aβ and the APP intracellular domain (AICD), referred to as γ and ε, respectively. The heterogeneous nature of the γ cleavage that produces various Aβ peptides is highly relevant to AD, as increased production of Aβ 1-42 is genetically and biochemically linked to the development of AD. We have identified an amino acid in the juxtamembrane region of APP, lysine 624, on the basis of APP695 numbering (position 28 relative to Aβ) that plays a critical role in determining the final length of Aβ peptides released by γ-secretase. Mutation of this lysine to alanine (K28A) shifts the primary site of γ-secretase cleavage from 1-40 to 1-33 without significant changes to ε cleavage. These results further support a model where ε cleavage occurs first, followed by sequential proteolysis of the remaining transmembrane fragment, but extend these observations by demonstrating that charged residues at the luminal boundary of the APP transmembrane domain limit processivity of γ-secretase.
authors.affiliation: Emory University, School of Medicine, Department of Pharmacology, Center for Neurodegenerative Disease, Atlanta, Georgia 30322, USA. tkukar@emory.edu
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Kukar
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Ladd
authors.forename: Paul
authors.initials: P
authors.lastname: Robertson
authors.forename: Sean A
authors.initials: SA
authors.lastname: Pintchovski
authors.forename: Brenda
authors.initials: B
authors.lastname: Moore
authors.forename: Maralyssa A
authors.initials: MA
authors.lastname: Bann
authors.forename: Zhao
authors.initials: Z
authors.lastname: Ren
authors.forename: Karen
authors.initials: K
authors.lastname: Jansen-West
authors.forename: Kim
authors.initials: K
authors.lastname: Malphrus
authors.forename: Simone
authors.initials: S
authors.lastname: Eggert
authors.forename: Hiroko
authors.initials: H
authors.lastname: Maruyama
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Cottrell
authors.forename: Pritam
authors.initials: P
authors.lastname: Das
authors.forename: Guriqbal S
authors.initials: GS
authors.lastname: Basi
authors.forename: Edward H
authors.initials: EH
authors.lastname: Koo
authors.forename: Todd E
authors.initials: TE
authors.lastname: Golde
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000235:genetics / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008239:Lysine / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D059748:Proteolysis
chemical_list: C545487:APP protein, human; D016564:Amyloid beta-Protein Precursor; D053829:Amyloid Precursor Protein Secretases; D008239:Lysine