Crystal structure of Escherichia coli MscS, a voltage-modulated and mechanosensitive channel.
The mechanosensitive channel of small conductance (MscS) responds both to stretching of the cell membrane and to membrane depolarization. The crystal structure at 3.9 angstroms resolution demonstrates that Escherichia coli MscS folds as a membrane-spanning heptamer with a large cytoplasmic region. Each subunit contains three transmembrane helices (TM1, -2, and -3), with the TM3 helices lining the pore, while TM1 and TM2, with membrane-embedded arginines, are likely candidates for the tension and voltage sensors. The transmembrane pore, apparently captured in an open state, connects to a large chamber, formed within the cytoplasmic region, that connects to the cytoplasm through openings that may function as molecular filters. Although MscS is likely to be structurally distinct from other ion channels, similarities in gating mechanisms suggest common structural elements.
Bass
Randal B
RB
Division of Chemistry and Chemical Engineering, Biochemistry Option, Howard Hughes Medical Institute, Mail Code 114-96, California Institute of Technology, Pasadena, CA 91125, USA.
Strop
Pavel
P
Barclay
Margaret
M
Rees
Douglas C
DC
D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry; D002462:Cell Membrane / Q000737:chemistry / Q000502:physiology; D003460:Crystallization; D018360:Crystallography, X-Ray; D004553:Electric Conductivity; D004926:Escherichia coli / Q000737:chemistry* / Q000502:physiology; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000502:physiology*; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry* / Q000502:physiology*; D040542:Mechanotransduction, Cellular; D008564:Membrane Potentials; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D016415:Sequence Alignment
D029968:Escherichia coli Proteins; D007473:Ion Channels; C469542:MscS protein, E coli; D021122:Protein Subunits; D001120:Arginine