Structural basis of dual Ca(2+)/pH regulation of the endolysosomal TRPML1 channel.Li, M., Zhang, W.K., Benvin, N.M., Zhou, X., Su, D., Li, H., Wang, S., Michailidis, I.E., Tong, L., Li, X., Yang, J.
(2017) Nat Struct Mol Biol 24: 205-213
- PubMed: 28112729
- DOI: 10.1038/nsmb.3362
- Primary Citation of Related Structures:
5TJC, 5TJB, 5TJA
- PubMed Abstract:
The activities of organellar ion channels are often regulated by Ca 2+ and H + , which are present in high concentrations in many organelles. Here we report a structural element critical for dual Ca 2+ /pH regulation ...
The activities of organellar ion channels are often regulated by Ca 2+ and H + , which are present in high concentrations in many organelles. Here we report a structural element critical for dual Ca 2+ /pH regulation of TRPML1, a Ca 2+ -release channel crucial for endolysosomal function. TRPML1 mutations cause mucolipidosis type IV (MLIV), a severe lysosomal storage disorder characterized by neurodegeneration, mental retardation and blindness. We obtained crystal structures of the 213-residue luminal domain of human TRPML1 containing three missense MLIV-causing mutations. This domain forms a tetramer with a highly electronegative central pore formed by a novel luminal pore loop. Cysteine cross-linking and cryo-EM analyses confirmed that this architecture occurs in the full-length channel. Structure-function studies demonstrated that Ca 2+ and H + interact with the luminal pore and exert physiologically important regulation. The MLIV-causing mutations disrupt the luminal-domain structure and cause TRPML1 mislocalization. Our study reveals the structural underpinnings of TRPML1's regulation, assembly and pathogenesis.
Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province; and Ion Channel Research and Drug Development Center, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.