Sampling the conformational space of the catalytic subunit of human γ-secretase
Abstract
Human γ-Secretase is an intra-membrane protease that cleaves many substrates. Aberrant cleavage of Notch is implicated in cancer, while abnormalities in cutting amyloid precursor protein lead to Alzheimer's disease. Our previous cryo-EM structure of γ-secretase revealed considerable disorder in its catalytic subunit presenilin. Here, we describe an image classification procedure that characterizes molecular plasticity at the secondary structure level, and apply this method to identify three distinct conformations in our previous sample. In one of these conformations, an additional transmembrane helix is visible that cannot be attributed to known components of γ-secretase. In addition, we present a γ-secretase structure in complex with the dipeptidic inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT). Our results reveal how conformational mobility in the second and sixth transmembrane helices of presenilin is greatly reduced upon binding of DAPT or the additional helix, and form the basis for a new model of how substrate enters the transmembrane domain.
Article and author information
Author details
Reviewing Editor
- Werner Kühlbrandt, Max Planck Institute of Biophysics, Germany
Version history
- Received: August 27, 2015
- Accepted: November 30, 2015
- Accepted Manuscript published: December 1, 2015 (version 1)
- Version of Record published: January 7, 2016 (version 2)
Copyright
© 2015, Bai et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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