Activation and intrinsic gamma-secretase activity of presenilin 1.
A complex composed of presenilin (PS), nicastrin, PEN-2, and APH-1 is absolutely required for γ-secretase activity in vivo. Evidence has emerged to suggest a role for PS as the catalytic subunit of γ-secretase, but it has not been established that PS is catalytically active in the absence of associated subunits. We now report that bacterially synthesized, recombinant PS (rPS) reconstituted into liposomes exhibits γ-secretase activity. Moreover, an rPS mutant that lacks a catalytic aspartate residue neither exhibits reconstituted γ-secretase activity nor interacts with a transition-state γ-secretase inhibitor. Importantly, we demonstrate that rPS harboring mutations that cause early onset familial Alzheimer's disease (FAD) lead to elevations in the ratio of Aβ42 to Aβ40 peptides produced from a wild-type APP substrate and that rPS enhances the Aβ42/Aβ40 peptide ratio from FAD-linked mutant APP substrates, findings that are entirely consistent with the results obtained in in vivo settings. Thus, γ-secretase cleavage specificity is an inherent property of the polypeptide. Finally, we demonstrate that PEN2 is sufficient to promote the endoproteolysis of PS1 to generate the active form of γ-secretase. Thus, we conclusively establish that activated PS is catalytically competent and the bimolecular interaction of PS1 and PEN2 can convert the PS1 zymogen to an active protease.
Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065.
Kwangwook
K
Ahn
Christopher C
CC
Shelton
Yuan
Y
Tian
Xulun
X
Zhang
M Lane
ML
Gilchrist
Sangram S
SS
Sisodia
Yue-Ming
YM
Li
D000544:Alzheimer Disease / Q000201:enzymology / Q000235:genetics; D053829:Amyloid Precursor Protein Secretases / Q000235:genetics / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000235:genetics / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D053764:Presenilin-1 / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D011510:Proteolipids / Q000737:chemistry; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D008565:Membrane Proteins; C508853:PSEN1 protein, human; C469349:PSENEN protein, human; D010446:Peptide Fragments; D053764:Presenilin-1; D021122:Protein Subunits; D011510:Proteolipids; D011994:Recombinant Proteins; C020485:proteoliposomes; D053829:Amyloid Precursor Protein Secretases