RT Journal Article
SR Electronic
T1 Sampling the conformational space of the catalytic subunit of human γ-secretase
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 025890
DO 10.1101/025890
A1 Xiao-chen Bai
A1 Eeson Rajendra
A1 Guanghui Yang
A1 Yigong Shi
A1 Sjors H. W Scheres
YR 2015
UL http://biorxiv.org/content/early/2015/09/01/025890.abstract
AB Human γ-secretase is an intra-membrane protease that cleaves many different 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 introduce 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 the 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.