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Proc Natl Acad Sci U S A. 2015 May 12;112(19):6003-8. doi: 10.1073/pnas.1506242112. Epub 2015 Apr 27.

Structural basis of human γ-secretase assembly.

Author information

1
Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
2
Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Joint Center for Life Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China shi-lab@tsinghua.edu.cn.

Abstract

The four-component intramembrane protease γ-secretase is intricately linked to the development of Alzheimer's disease. Despite recent structural advances, the transmembrane segments (TMs) of γ-secretase remain to be specifically assigned. Here we report a 3D structure of human γ-secretase at 4.32-Å resolution, determined by single-particle, electron cryomicroscopy in the presence of digitonin and with a T4 lysozyme fused to the amino terminus of presenilin 1 (PS1). The overall structure of this human γ-secretase is very similar to that of wild-type γ-secretase determined in the presence of amphipols. The 20 TMs are unambiguously assigned to the four components, revealing principles of subunit assembly. Within the transmembrane region, PS1 is centrally located, with its amino-terminal fragment (NTF) packing against Pen-2 and its carboxyl-terminal fragment (CTF) interacting with Aph-1. The only TM of nicastrin associates with Aph-1 at the thick end of the TM horseshoe, and the extracellular domain of nicastrin directly binds Pen-2 at the thin end. TM6 and TM7 in PS1, which harbor the catalytic aspartate residues, are located on the convex side of the TM horseshoe. This structure serves as an important framework for understanding the function and mechanism of γ-secretase.

KEYWORDS:

Alzheimer’s disease; Presenilin; cryo-EM structure; intramembrane protease; γ-secretase

PMID:
25918421
PMCID:
PMC4434707
DOI:
10.1073/pnas.1506242112
[Indexed for MEDLINE]
Free PMC Article

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