Small-conductance mechanosensitive channel - P0C0S1 (MSCS_ECOLI)


Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for P0C0S1: 7
Mechanosensitive channel that participates in the regulation of osmotic pressure changes within the cell, opening in response to stretch forces in the membrane lipid bilayer, without the need for other proteins. Contributes to normal resistance to hypoosmotic shock. Forms an ion channel of 1.0 nanosiemens conductance with a slight preference for anions. The channel is sensitive to voltage; as the membrane is depolarized, less tension is required to open the channel and vice versa. The channel is characterized by short bursts of activity that last for a few seconds. UniProt
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Subunit Structure
Homoheptamer. UniProt
The channel pore is formed by TM3 and the loop between TM2 and TM3. After a sharp turn at Gly-113, an alpha-helix (residues 114-127) is oriented nearly parallel to the plane of the putative lipid bilayer. On the intracellular side of the channel, the permeation pathway of MscS does not connect directly to the cytoplasm but instead opens to a large chamber that is connected to the cytoplasm. This chamber resembles a molecular filter that could serve to prescreen large molecules before they are allowed passage to the transmembrane pore. The TM1 and TM2 helices appear to be likely candidates for mediating the tension and voltage sensitivities of MscS. Gating requires large rearrangements of at least the C-terminus, and is probably influenced by freely exchangeable membrane lipids that bind in grooves and pockets between the transmembrane helices and enhance the stability of the closed channel conformation. In a hypoosmotic environment the membrane is stretched, and lipids may be pulled into the lipid bilayer and away from the protein, which is predicted to destabilize the closed conformation and promote channel gating. UniProt
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