Computational Studies of the Cholesterol Transport between NPC2 and the N-Terminal Domain of NPC1 (NPC1(NTD))

Estiú, Guillermina; Khatri, Nazir A.; Wiest, Olaf

doi:10.1021/bi4005478

Cited by 30 publications

(63 citation statements)

References 52 publications

(118 reference statements)

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“…The proximity and interaction of these pockets could trigger sterol transfer from NPC2 to NPC1's NTD, consistent with biochemical data that suggest that NPC2-NPC1 interaction catalyzes this process (13). It is important to note that NPC2 binding to NPC1 may trigger a conformational change(s) that reorients NPC1 NTD into a more planar configuration in relation to NPC2 to accomplish actual cholesterol transfer, as previously modeled (19,21). Alanine scanning mutagenesis identified three NPC2 residues, M79, V81, and V83, as being needed for cholesterol transfer from NPC2 to NPC1's NTD, but not for cholesterol binding; P120 influenced cholesterol binding (19).…”

Section: Discussionsupporting

confidence: 82%

“…In this state, the two cholesterol-binding pockets can be aligned to form a cholesterol-transfer tunnel (Fig. 5B), although the angle of this interaction is more acute than previous proposals (19,21). The proximity and interaction of these pockets could trigger sterol transfer from NPC2 to NPC1's NTD, consistent with biochemical data that suggest that NPC2-NPC1 interaction catalyzes this process (13).…”

Section: Discussionsupporting

confidence: 81%

“…Previous work has provided the crystal structures of both NPC2 (12) and NPC1-NTD with bound sterol (14), and others have tried to model the interface between these proteins by model building and molecular dynamics simulation (19,21). Instead, we have docked the crystal structure of the NPC1-MLD-NPC2 complex onto the NPC1 cryo-EM structure (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Clues to the mechanism of cholesterol transfer from the structure of NPC1 middle lumenal domain bound to NPC2

Saha

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

161

189

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Export of LDL-derived cholesterol from lysosomes requires the cooperation of the integral membrane protein Niemann–Pick C1 (NPC1) and a soluble protein, Niemann–Pick C2 (NPC2). Mutations in the genes encoding these proteins lead to Niemann–Pick disease type C (NPC). NPC2 binds to NPC1’s second (middle), lumenally oriented domain (MLD) and transfers cholesterol to NPC1’s N-terminal domain (NTD). Here, we report the 2.4-Å resolution crystal structure of a complex of human NPC1–MLD and NPC2 bearing bound cholesterol-3-O-sulfate. NPC1–MLD uses two protruding loops to bind NPC2, analogous to its interaction with the primed Ebola virus glycoprotein. Docking of the NPC1–NPC2 complex onto the full-length NPC1 structure reveals a direct cholesterol transfer tunnel between NPC2 and NTD cholesterol binding pockets, supporting the “hydrophobic hand-off” cholesterol transfer model.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionsupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Clues to the mechanism of cholesterol transfer from the structure of NPC1 middle lumenal domain bound to NPC2

Saha

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

161

189

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“…Superposition of these crystal structures onto the previously modeled 6,14 NPC1-NPC2 cholesterol complex (Figure 6a) showed that the isooctyl tail of cholesterol in NPC1 and the hydroxyl head of cholesterol sulfate in NPC2 are separated by approximately 5 Å. In an extended conformation, this distance corresponds to five linker atoms.…”

Section: Resultsmentioning

confidence: 92%

“…12 The precise details of the interaction of NPC1 and NPC2 proteins during the critical cholesterol hand-off have only begun to be elucidated, 13 and computational modeling has also been used to probe this interaction. 14,15 Finally, how the NPC1-bound cholesterol is transported across the lysosome membrane and whether a cytosolically-oriented protein drives the transfer equilibrium by receiving cholesterol from NPC1 is not yet known.…”

Section: Introductionmentioning

confidence: 99%

Design and synthesis of a crosslinker for studying intracellular steroid trafficking pathways

Byrd

Arieno

Kennelly

et al. 2015

Bioorganic & Medicinal Chemistry

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A crosslinker was designed and synthesized as a molecular tool for potential use in probing the intracellular trafficking pathways of steroids. The design was guided by computational modeling based upon a model for the transfer of cholesterol between two proteins, NPC1 and NPC2. These proteins play critical roles in the transport of low-density lipoprotein-derived cholesterol from the lumen of lysosomes to other subcellular compartments. Two modified cholesterol residues were covalently joined by a tether based on molecular modeling of the transient interaction of NPC1 and NPC2 during the transfer of cholesterol from the binding site of one of these proteins to the other. With two cholesterol molecules appropriately connected, we hypothesize that the cholesterol binding sites of both proteins will be simultaneously occupied in a manner that will stabilize the protein-protein interaction to permit detailed structural analysis of the resulting complex. A photoaffinity label has also been introduced into one of the cholesterol cores to permit covalent attachment of one of the units into its respective protein-binding pocket. The basic design of these crosslinkers should render them useful for examining interactions of the NPC1/NPC2 pair as well as other sterol transport proteins.

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Comparative study of the effect of disease causing and benign mutations in position Q92 on cholesterol binding by the NPC1 n‐terminal domain

Petukh

Zhulin

2018

Proteins

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The Niemann-Pick type C1 (NPC1) protein is a large transmembrane protein located in lysosomes/endosomes. NPC1 binds cholesterol (CLR) and transports it to cellular membrane and endoplasmic reticulum. Mutations in NPC1 cause Niemann-Pick type C (NPC) disease, a rare autosomal disorder characterized by intracellular accumulations of CLR and subsequent neurodegeneration leading to premature death. Among known disease-causing mutations in NPC1, Q92R is the one that is located in the N-terminal cholesterol-binding domain [NTD]. Here we study the effect of the mutation on the ability of NPC1 (NTD) to bind and retain CLR in the binding pocket using structural analysis. We compare characteristics of the Q92R and Q92S mutant type (MT) protein, which is predicted to be benign. We provide detailed investigation of the CLR-NPC1 (NTD) binding process; and propose the mechanism, by which Q92R mutation causes NPC disease. We show that although Q92 residue neither directly participates in catalytic activity of the NPC1 (NTD), nor defines its CLR-binding specificity - it is important for the overall protein structure as well as for providing favorable electrostatic environment for CLR transfer. Our results suggest that a negative electrostatic potential of the CLR binding site (the S-opening) might promote NPC2 interaction with NPC1 (NTD) and/or proper CLR orientation and its enforced transfer. We show that in contrast to the benign Q92S mutation, Q92R significantly reduces electrostatic potential around S-opening, and thus likely affects NPC1 (NTD)-NPC2 interaction and/or CLR transfer from NPC2 to NPC1.

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Computational Studies of the Cholesterol Transport between NPC2 and the N-Terminal Domain of NPC1 (NPC1(NTD))

Cited by 30 publications

References 52 publications

Clues to the mechanism of cholesterol transfer from the structure of NPC1 middle lumenal domain bound to NPC2

Clues to the mechanism of cholesterol transfer from the structure of NPC1 middle lumenal domain bound to NPC2

Design and synthesis of a crosslinker for studying intracellular steroid trafficking pathways

Comparative study of the effect of disease causing and benign mutations in position Q92 on cholesterol binding by the NPC1 n‐terminal domain

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