Dimerization of β-site β-amyloid precursor protein-cleaving enzyme

Westmeyer, Gil G.; Willem, Michael; Lichtenthaler, Stefan F.; Lurman, Glenn; Multhaup, Gerd; Assfalg-Machleidt, Irmgard; Reiss, Karina; Saftig, Paul; Haass, Christian (2004). Dimerization of β-site β-amyloid precursor protein-cleaving enzyme. Journal of biological chemistry, 279(51), pp. 53205-53212. American Society for Biochemistry and Molecular Biology 10.1074/jbc.M410378200

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Cleavage of the beta-amyloid precursor protein (APP) by the aspartyl protease beta-site APP-cleaving enzyme (BACE) is the first step in the generation of the amyloid beta-peptide, which is deposited in the brain of Alzheimer's disease patients. Whereas the subsequent cleavage by gamma-secretase was shown to originate from the cooperation of a multicomponent complex, it is currently unknown whether in a cellular environment BACE is enzymatically active as a monomer or in concert with other proteins. Using blue native gel electrophoresis we found that endogenous and overexpressed BACE has a molecular mass of 140 kDa instead of the expected mass of 70 kDa under denaturing conditions. This suggests that under native conditions BACE exists as a homodimer. Homodimerization was confirmed by co-immunoprecipitation of full-length BACE carrying different epitope tags. In contrast, the soluble active BACE ectodomain was exclusively present as a monomer both under native and denaturing conditions. A domain analysis revealed that the BACE ectodomain dimerized as long as it was attached to the membrane, whereas the cytoplasmic domain and the transmembrane domain were dispensable for dimerization. By adding a KKXX-endoplasmic reticulum retention signal to BACE, we demonstrate that dimerization of BACE occurs already before full maturation and pro-peptide cleavage. Furthermore, kinetic analysis of the purified native BACE dimer revealed a higher affinity and turnover rate in comparison to the monomeric soluble BACE. Dimerization of BACE might, thus, facilitate binding and cleavage of physiological substrates.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy > Functional Anatomy

UniBE Contributor:

Lurman, Glenn

Subjects:

500 Science > 570 Life sciences; biology

ISSN:

0021-9258

Publisher:

American Society for Biochemistry and Molecular Biology

Language:

English

Submitter:

Glenn Lurman

Date Deposited:

01 Sep 2014 14:26

Last Modified:

25 Dec 2014 13:26

Publisher DOI:

10.1074/jbc.M410378200

PubMed ID:

15485862

BORIS DOI:

10.7892/boris.46886

URI:

https://boris.unibe.ch/id/eprint/46886

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