Conformational changes in the Niemann-Pick type C1 protein NCR1 drive sterol translocation.

Autor:	Frain KM; Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark., Dedic E; Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark., Nel L; Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark., Bohush A; Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark.; Department of Molecular Biology and Genetics, Aarhus Institute of Advanced Studies, Aarhus University, Aarhus C 8000, Denmark., Olesen E; Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark., Thaysen K; Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M 5230, Denmark., Wüstner D; Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense M 5230, Denmark., Stokes DL; Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016., Pedersen BP; Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2024 Apr 09; Vol. 121 (15), pp. e2315575121. Date of Electronic Publication: 2024 Apr 03.
DOI:	10.1073/pnas.2315575121
Abstrakt:	The membrane protein Niemann-Pick type C1 (NPC1, named NCR1 in yeast) is central to sterol homeostasis in eukaryotes. Saccharomyces cerevisiae NCR1 is localized to the vacuolar membrane, where it is suggested to carry sterols across the protective glycocalyx and deposit them into the vacuolar membrane. However, documentation of a vacuolar glycocalyx in fungi is lacking, and the mechanism for sterol translocation has remained unclear. Here, we provide evidence supporting the presence of a glycocalyx in isolated S. cerevisiae vacuoles and report four cryo-EM structures of NCR1 in two distinct conformations, named tense and relaxed. These two conformations illustrate the movement of sterols through a tunnel formed by the luminal domains, thus bypassing the barrier presented by the glycocalyx. Based on these structures and on comparison with other members of the Resistance-Nodulation-Division (RND) superfamily, we propose a transport model that links changes in the luminal domains with a cycle of protonation and deprotonation within the transmembrane region of the protein. Our model suggests that NPC proteins work by a generalized RND mechanism where the proton motive force drives conformational changes in the transmembrane domains that are allosterically coupled to luminal/extracellular domains to promote sterol transport. Competing Interests: Competing interests statement:The authors declare no competing interest.
Databáze:	MEDLINE
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