@article{2b8543271d4e4c8f882d4732008aff9f,
title = "Structural basis for sterol sensing by Scap and Insig",
abstract = "The sterol regulatory element-binding protein (SREBP) pathway monitors the cellular cholesterol level through sterol-regulated association between the SREBP cleavage-activating protein (Scap) and the insulin-induced gene (Insig). Despite structural determination of the Scap and Insig-2 complex bound to 25-hydroxycholesterol, the luminal domains of Scap remain unresolved. In this study, combining cryogenic electron microscopy (cryo-EM) analysis and artificial intelligence-facilitated structural prediction, we report the structure of the human Scap/Insig-2 complex purified in digitonin. The luminal domain loop 1 and a co-folded segment in loop 7 of Scap resemble those of the luminal/extracellular domain in NPC1 and related proteins, providing clues to the cholesterol-regulated interaction of loop 1 and loop 7. An additional luminal interface is observed between Scap and Insig. We also show that Scap(D428A), which inhibits SREBP activation even under sterol depletion, exhibits an identical conformation with the wild-type protein when complexed with Insig-2, and its constitutive suppression of the SREBP pathway may also involve a later step in protein trafficking.",
keywords = "Insig, Loop 1, Loop 7, SREBP pathway, Scap, cholesterol metabolism, cryo-EM structure, sterol sensing domain",
author = "Renhong Yan and Pingping Cao and Wenqi Song and Yaning Li and Tongtong Wang and Hongwu Qian and Chuangye Yan and Nieng Yan",
note = "Funding Information: We thank the Cryo-EM Facility and the supercomputer center of Westlake University and the Tsinghua University Branch of China National Center for Protein Sciences (Beijing) for providing cryo-EM and computation support. We thank Xiaomin Li (Tsinghua University) for technical support during EM image acquisition. This work was funded by the National Key R&D Program of China (2020YFA0509301 to C.Y.) from the Ministry of Science and Technology of China, the Beijing Nova Program (Z201100006820039 to C.Y.), the China Postdoctoral Science Foundation (2020M681937 to R.Y.), and the National Postdoctoral Program for Innovative Talents of China (BX20200304 to R.Y.). N.Y. acknowledges the Ministry of Science and Technology of China and the National Natural Science Foundation of China for multiple funds that have supported this research in 2008–2017. N.Y. has been supported by the Shirley M. Tilghman Endowed Professorship from Princeton University since 2017. N.Y. conceived and supervised the project. N.Y. R.Y. P.C. W.S. H.Q. and C.Y. designed the experiments. R.Y. Y.L. P.C. and W.S. performed molecular cloning, protein purification, and cryo-EM data acquisition. P.C. W.S. R.Y. Y.L. and T.W. performed all functional assays. C.Y. performed data processing and structural building and refinement. All authors contributed to data analysis. N.Y. and C.Y. wrote the manuscript. The authors declare no competing interests. Funding Information: We thank the Cryo-EM Facility and the supercomputer center of Westlake University and the Tsinghua University Branch of China National Center for Protein Sciences (Beijing) for providing cryo-EM and computation support. We thank Xiaomin Li (Tsinghua University) for technical support during EM image acquisition. This work was funded by the National Key R&D Program of China ( 2020YFA0509301 to C.Y.) from the Ministry of Science and Technology of China , the Beijing Nova Program ( Z201100006820039 to C.Y.), the China Postdoctoral Science Foundation ( 2020M681937 to R.Y.), and the National Postdoctoral Program for Innovative Talents of China ( BX20200304 to R.Y.). N.Y. acknowledges the Ministry of Science and Technology of China and the National Natural Science Foundation of China for multiple funds that have supported this research in 2008–2017. N.Y. has been supported by the Shirley M. Tilghman Endowed Professorship from Princeton University since 2017. Publisher Copyright: {\textcopyright} 2021 The Author(s)",
year = "2021",
month = jun,
day = "29",
doi = "10.1016/j.celrep.2021.109299",
language = "English (US)",
volume = "35",
journal = "Cell Reports",
issn = "2211-1247",
publisher = "Cell Press",
number = "13",
}