Abstract
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.
Keywords:
Ebola virus glycoprotein; Niemann–Pick type C disease; cholesterol trafficking; crystal structure.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Motifs
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Binding Sites
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Biological Transport
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Carrier Proteins / chemistry*
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Cholesterol Esters / chemistry*
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Cholesterol Esters / metabolism
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Cloning, Molecular
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Crystallography, X-Ray
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Escherichia coli / genetics
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Escherichia coli / metabolism
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Gene Expression
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Genetic Vectors / chemistry
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Genetic Vectors / metabolism
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Glycoproteins / chemistry*
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Glycoproteins / genetics
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Glycoproteins / metabolism
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Humans
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Hydrophobic and Hydrophilic Interactions
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Intracellular Signaling Peptides and Proteins
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Kinetics
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Lysosomes / metabolism*
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Membrane Glycoproteins / chemistry*
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Membrane Glycoproteins / genetics
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Membrane Glycoproteins / metabolism
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Molecular Docking Simulation
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Niemann-Pick C1 Protein
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Protein Binding
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Protein Conformation, alpha-Helical
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Protein Conformation, beta-Strand
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Protein Interaction Domains and Motifs
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Vesicular Transport Proteins
Substances
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Carrier Proteins
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Cholesterol Esters
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Glycoproteins
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Intracellular Signaling Peptides and Proteins
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Membrane Glycoproteins
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NPC1 protein, human
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NPC2 protein, human
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Niemann-Pick C1 Protein
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Recombinant Proteins
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Vesicular Transport Proteins
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cholesteryl sulfate