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Title | Structural mechanisms of phospholipid activation of the human TPC2 channel. |
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Journal, issue, pages | Elife, Vol. 8, Year 2019 |
Publish date | Mar 12, 2019 |
Authors | Ji She / Weizhong Zeng / Jiangtao Guo / Qingfeng Chen / Xiao-Chen Bai / Youxing Jiang / |
PubMed Abstract | Mammalian two-pore channels (TPCs) regulate the physiological functions of the endolysosome. Here we present cryo-EM structures of human TPC2 (HsTPC2), a phosphatidylinositol 3,5-bisphosphate (PI(3,5) ...Mammalian two-pore channels (TPCs) regulate the physiological functions of the endolysosome. Here we present cryo-EM structures of human TPC2 (HsTPC2), a phosphatidylinositol 3,5-bisphosphate (PI(3,5)P)-activated, Na selective channel, in the ligand-bound and apo states. The apo structure captures the closed conformation, while the ligand-bound form features the channel in both open and closed conformations. Combined with functional analysis, these structures provide insights into the mechanism of PI(3,5)P-regulated gating of TPC2, which is distinct from that of TPC1. Specifically, the endolysosome-specific PI(3,5)P binds at the first 6-TM and activates the channel - independently of the membrane potential - by inducing a structural change at the pore-lining inner helix (IS6), which forms a continuous helix in the open state but breaks into two segments at Gly317 in the closed state. Additionally, structural comparison to the voltage-dependent TPC1 structure allowed us to identify Ile551 as being responsible for the loss of voltage dependence in TPC2. |
External links | Elife / PubMed:30860481 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.4 - 3.7 Å |
Structure data | EMDB-0477, PDB-6nq0: |
Chemicals | ChemComp-EUJ: |
Source |
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Keywords | TRANSPORT PROTEIN / channel / lysosome |