title: Differential effects of inhibitors on the gamma-secretase complex. Mechanistic implications.
abstract: Gamma-secretase is a protease complex of four integral membrane proteins, with presenilin (PS) as the apparent catalytic component, and this enzyme processes the transmembrane domains of a variety of substrates, including the amyloid beta-protein precursor and the Notch receptor. Here we explore the mechanisms of structurally diverse gamma-secretase inhibitors by examining their ability to displace an active site-directed photoprobe from PS heterodimers. Most gamma-secretase inhibitors, including a potent inhibitor of the PS-like signal peptide peptidase, blocked the photoprobe from binding to PS1, indicating that these compounds either bind directly to the active site or alter it through an allosteric interaction. Conversely, some reported inhibitors failed to displace this interaction, demonstrating that these compounds do not interfere with the protease by affecting its active site. Differential effects of the inhibitors with respect to photoprobe displacement and in cell-based and cell-free assays suggest that these compounds are important mechanistic tools for deciphering the workings of this intramembrane-cleaving protease complex and its similarity to other polytopic aspartyl proteases.
authors.affiliation: Center for Neurologic Diseases, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Anna Y
authors.initials: AY
authors.lastname: Kornilova
authors.forename: Chittaranjan
authors.initials: C
authors.lastname: Das
authors.forename: Michael S
authors.initials: MS
authors.lastname: Wolfe
mesh_terms: D000544:Alzheimer Disease / Q000201:enzymology; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; D010450:Endopeptidases / Q000737:chemistry / Q000187:drug effects*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry; D010777:Photochemistry; D013329:Structure-Activity Relationship
chemical_list: D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human