Evidence for dimeric BACE-mediated APP processing.
beta-Secretase (BACE) is an aspartyl protease, which proteolytically processes amyloid precursor protein, making BACE an interesting pharmacological target in Alzheimer's disease. To study the enzymatic function of BACE, we mutated either of the two aspartic acid residues in the active site of BACE. This rendered BACE functionally inactive without affecting the degree of glycosylation or endosomal localization. In contrast, substituting both active site aspartic acid residues produced a functionally inactive, endoplasmic reticulum-retained and partially glycosylated BACE. Interestingly, co-expression of the two single active site mutants partially restored beta-site cleavage of amyloid precursor protein, and the restored activity was inhibited with similar dose-dependency and potency as wildtype BACE by a small molecule inhibitor raised against BACE. In sum, our data suggest that two different active site mutants can complement each other in a partially functional BACE dimer and mediate APP processing.
Jin
Shaobo
S
Department of Cell and Molecular Biology, Karolinska Institute, SE-171 77 Stockholm, Sweden.
Agerman
Karin
K
Kolmodin
Karin
K
Gustafsson
Elin
E
Dahlqvist
Camilla
C
Jureus
Anders
A
Liu
Gang
G
Fälting
Johanna
J
Berg
Stefan
S
Lundkvist
Johan
J
Lendahl
Urban
U
D000544:Alzheimer Disease / Q000201:enzymology*; D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020134:Catalytic Domain / Q000235:genetics; D057927:Hydrophobic and Hydrophilic Interactions; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D055503:Protein Multimerization
D016564:Amyloid beta-Protein Precursor; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; C509282:Bace1 protein, mouse