title: Structural basis of dual Ca2+/pH regulation of the endolysosomal TRPML1 channel.
abstract: The activities of organellar ion channels are often regulated by Ca2+and H+, which are present in high concentrations in many organelles. Here we report a structural element critical for dual Ca2+/pH regulation of TRPML1, a Ca2+-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 Ca2+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.
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York, USA.
authors.forename: Minghui
authors.initials: M
authors.lastname: Li
authors.affiliation: 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.|Department of Pharmacology, School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan, China.
authors.forename: Wei K
authors.initials: WK
authors.lastname: Zhang
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York, USA.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Benvin
authors.affiliation: Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Zhou
authors.affiliation: 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.|Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, China.
authors.forename: Deyuan
authors.initials: D
authors.lastname: Su
authors.affiliation: 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.|Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Li
authors.affiliation: 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.|Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York, USA.
authors.forename: Ioannis E
authors.initials: IE
authors.lastname: Michailidis
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York, USA.
authors.forename: Liang
authors.initials: L
authors.lastname: Tong
authors.affiliation: Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Xueming
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York, USA.|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.
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D002118:Calcium / Q000378:metabolism*; D018360:Crystallography, X-Ray; D011992:Endosomes / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008247:Lysosomes / Q000378:metabolism*; D008958:Models, Molecular; D009081:Mucolipidoses / Q000235:genetics; D020125:Mutation, Missense; D011485:Protein Binding; D055503:Protein Multimerization; D021122:Protein Subunits / Q000378:metabolism; D015203:Reproducibility of Results; D055672:Static Electricity; D013329:Structure-Activity Relationship; D050053:TRPM Cation Channels / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D021122:Protein Subunits; D050053:TRPM Cation Channels; C492059:TRPM1 protein, human; D002118:Calcium