Single particle frozen electron microscope technology: TRPML3 channel new structural features.

Recently, the latest research results, jointly completed by the Kunming Institute of Zoology of the Chinese Academy of Sciences, Columbia University and Tsinghua University in the United States, were published in Nature and Structure and Molecular Biology under the title Cryo-EM Structures of human endososomal TRPML3 channel in three sdistinct.
researchers, using single-particle frozen electron micromicroscope technology, analyzed the high-resolution full-length structure of the human-derived lysozyme calcium ion channel TRPML3 in the closed state, the open state caused by an agonis and the acid pH suppression state, and revealed the unprecedented structural characteristics, which provided a new structural basis for the study of the activation and regulation mechanism and physiological function of the channel.
cell swallowing pathway plays an important role in intracellular signal conduction and cellular physiological response.
the various ion channels present in the connotation and lysosome seoids have a regulatory effect on the cell swallowing pathway, which is mainly distributed in the lysosome syntly body and the TRPML1 and TRPML3 ion channels are very important for cell membrane transport, cell autophagy, cell spitting and maintaining ion balance.
study found that instantaneous receptor potential channel member TRPML1 is the genetic determinant of MLIV, as many as 20 tRPML1 gene mutations can lead to MLIV.
, two spontaneous, functionally enhanced TRPML3 mutants (A419P and I362T) in mice can cause hearing loss and weakened physiological phenotypes, and these studies show that TRPML1 and TRPML3 channels play an important role in cellular physiological processes.
under normal cellular physiological conditions, the TRPML3 channel can be regulated by a variety of factors: PI (3,5) P2 activates The TRPML3 channel, and TRPML3 channel activity can be inhibited by acidic pH, Na plus and PI (4,5) P2 respectively.
a variety of synthetic small molecules such as ML-SA1 can specifically activate the TRPML channel, and these agonists are important for the study of the physiological function of TRPML channels. in
, by using a single-particle cryo-EM cryo-EM, the researchers successfully analyzed the high-resolution structures of the full-length human-derived TRPML3 ion channel in the closed state, the open state caused by the combination of agonists, and the low pH suppression state (4.06, 3.62 and 4.65?) respectively.
3D structure shows the agonisant ML-SA1 binding between the transmembrane domain S5 and S6 and induces the opening of the Gated Components of the S6.
structure shows a number of unique structural features: polycystin-mucoliindomain (POLYcystin-mucolipin domain, PMD) constitutes the organ-in-cavity (luminal cap) structure, s1 transmembrane a spiral section extends to the hat structure, and a helix is connected to form a "door door" Gating rod, which is directly connected to the cavity hole ring (luminal pore loop), which undergoes a drastic conformation almost change under acidic pH conditions, and the trans-membrane a helix S2 extends to the inner part of the cell and interacts with multiple inner structure areas to form the "gating handle" (gating knob).
combined with electrophysiological experiments, these unique structural features suggest a new channel regulation mechanism, namely, the cavity low pH and other physiological regulatory factors (such as PIP2), through the result of S1 and S2 conformation changes, the TRPML3 channel function is adjusted. The work of
reveals the new structural characteristics of TRPML3 channel and the conformational changes in channel activation and regulation, provides a structural basis for further study of the regulation mechanism of TRPML3 channel, and provides clues for solving the causes of abnormal channel function caused by pathogenic mutations.
research has been supported by the National Key Basic Research and Development Program (973 Plan), the National Natural Science Foundation project, the Yunnan Provincial Science and Technology Department's overseas high-end talents, the Yunnan High-Level Talent Project, the Youth Thousand Program and the National Institutes of Health in the United States.
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