TY - JOUR
T1 - Structure of the catalytic pore of γ-secretase probed by the accessibility of substituted cysteines
AU - Sato, Chihiro
AU - Morohashi, Yuichi
AU - Tomita, Taisuke
AU - Iwatsubo, Takeshi
PY - 2006/11/15
Y1 - 2006/11/15
N2 - Several single-span membrane proteins are cleaved within their transmembrane domains (TMDs) by intramembrane-cleaving proteases, although the structure of the active site executing intramembrane cleavage remains unknown. Here we use the substituted cysteine accessibility method to examine the structure of presenilin-1, a catalytic subunit of α-secretase, involved in amyloid β protein generation in Alzheimer's disease and Notch signaling. We show that TMD6 and TMD7 of presenilin-1 contribute to the formation of a hydrophilic pore within the membrane. Residues at the luminal portion of TMD6 are predicted to form a subsite for substrate or inhibitor binding on the α-helix facing a hydrophilic milieu, whereas those around the GxGD catalytic motif within TMD7 are highly water accessible, suggesting formation of a hydrophilic structure within the pore. Collectively, our data suggest that the active site of γ-secretase resides in a catalytic pore filled with water within the lipid bilayer and is tapered around the catalytic aspartates.
AB - Several single-span membrane proteins are cleaved within their transmembrane domains (TMDs) by intramembrane-cleaving proteases, although the structure of the active site executing intramembrane cleavage remains unknown. Here we use the substituted cysteine accessibility method to examine the structure of presenilin-1, a catalytic subunit of α-secretase, involved in amyloid β protein generation in Alzheimer's disease and Notch signaling. We show that TMD6 and TMD7 of presenilin-1 contribute to the formation of a hydrophilic pore within the membrane. Residues at the luminal portion of TMD6 are predicted to form a subsite for substrate or inhibitor binding on the α-helix facing a hydrophilic milieu, whereas those around the GxGD catalytic motif within TMD7 are highly water accessible, suggesting formation of a hydrophilic structure within the pore. Collectively, our data suggest that the active site of γ-secretase resides in a catalytic pore filled with water within the lipid bilayer and is tapered around the catalytic aspartates.
KW - Alzheimer's disease
KW - Aβ
KW - Intramembrane-cleaving protease
KW - Peptide
KW - Presenilin
KW - Proteolysis
KW - Structure
KW - Substituted cysteine accessibility method
UR - http://www.scopus.com/inward/record.url?scp=33751087756&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.3614-06.2006
DO - 10.1523/JNEUROSCI.3614-06.2006
M3 - Article
C2 - 17108181
AN - SCOPUS:33751087756
SN - 0270-6474
VL - 26
SP - 12081
EP - 12088
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 46
ER -