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Title: 3.3 Å structure of Niemann–Pick C1 protein reveals insights into the function of the C-terminal luminal domain in cholesterol transport

Abstract

Niemann–Pick C1 (NPC1) and NPC2 proteins are indispensable for the export of LDL-derived cholesterol from late endosomes. Mutations in these proteins result in Niemann–Pick type C disease, a lysosomal storage disease. Despite recent reports of the NPC1 structure depicting its overall architecture, the function of its C-terminal luminal domain (CTD) remains poorly understood even though 45% of NPC disease-causing mutations are in this domain. Here, we report a crystal structure at 3.3 Å resolution of NPC1* (residues 314–1,278), which—in contrast to previous lower resolution structures—features the entire CTD well resolved. Notably, all eight cysteines of the CTD form four disulfide bonds, one of which (C909–C914) enforces a specific loop that in turn mediates an interaction with a loop of the N-terminal domain (NTD). Importantly, this loop and its interaction with the NTD were not observed in any previous structures due to the lower resolution. Our mutagenesis experiments highlight the physiological relevance of the CTD–NTD interaction, which might function to keep the NTD in the proper orientation for receiving cholesterol from NPC2. Additionally, this structure allows us to more precisely map all of the disease-causing mutations, allowing future molecular insights into the pathogenesis of NPC disease.

Authors:
; ORCiD logo; ORCiD logo; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
NIHOTHERHHMI
OSTI Identifier:
1390867
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proceedings of the National Academy of Sciences of the United States of America; Journal Volume: 114; Journal Issue: 34
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES

Citation Formats

Li, Xiaochun, Lu, Feiran, Trinh, Michael N., Schmiege, Philip, Seemann, Joachim, Wang, Jiawei, and Blobel, Günter. 3.3 Å structure of Niemann–Pick C1 protein reveals insights into the function of the C-terminal luminal domain in cholesterol transport. United States: N. p., 2017. Web. doi:10.1073/pnas.1711716114.
Li, Xiaochun, Lu, Feiran, Trinh, Michael N., Schmiege, Philip, Seemann, Joachim, Wang, Jiawei, & Blobel, Günter. 3.3 Å structure of Niemann–Pick C1 protein reveals insights into the function of the C-terminal luminal domain in cholesterol transport. United States. doi:10.1073/pnas.1711716114.
Li, Xiaochun, Lu, Feiran, Trinh, Michael N., Schmiege, Philip, Seemann, Joachim, Wang, Jiawei, and Blobel, Günter. Mon . "3.3 Å structure of Niemann–Pick C1 protein reveals insights into the function of the C-terminal luminal domain in cholesterol transport". United States. doi:10.1073/pnas.1711716114.
@article{osti_1390867,
title = {3.3 Å structure of Niemann–Pick C1 protein reveals insights into the function of the C-terminal luminal domain in cholesterol transport},
author = {Li, Xiaochun and Lu, Feiran and Trinh, Michael N. and Schmiege, Philip and Seemann, Joachim and Wang, Jiawei and Blobel, Günter},
abstractNote = {Niemann–Pick C1 (NPC1) and NPC2 proteins are indispensable for the export of LDL-derived cholesterol from late endosomes. Mutations in these proteins result in Niemann–Pick type C disease, a lysosomal storage disease. Despite recent reports of the NPC1 structure depicting its overall architecture, the function of its C-terminal luminal domain (CTD) remains poorly understood even though 45% of NPC disease-causing mutations are in this domain. Here, we report a crystal structure at 3.3 Å resolution of NPC1* (residues 314–1,278), which—in contrast to previous lower resolution structures—features the entire CTD well resolved. Notably, all eight cysteines of the CTD form four disulfide bonds, one of which (C909–C914) enforces a specific loop that in turn mediates an interaction with a loop of the N-terminal domain (NTD). Importantly, this loop and its interaction with the NTD were not observed in any previous structures due to the lower resolution. Our mutagenesis experiments highlight the physiological relevance of the CTD–NTD interaction, which might function to keep the NTD in the proper orientation for receiving cholesterol from NPC2. Additionally, this structure allows us to more precisely map all of the disease-causing mutations, allowing future molecular insights into the pathogenesis of NPC disease.},
doi = {10.1073/pnas.1711716114},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 34,
volume = 114,
place = {United States},
year = {Mon Aug 07 00:00:00 EDT 2017},
month = {Mon Aug 07 00:00:00 EDT 2017}
}