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Ciliates and flagellates temporarily swim backwards on collision by generating a mechanoreceptor potential. Although this potential has been shown to be associated with cilia in Paramecium, the molecular entity of the mechanoreceptor has remained unknown. Here we show that Chlamydomonas cells express TRP11, a member of the TRP (transient receptor potential)(More)
MscL is a bacterial mechanosensitive channel that is activated directly by membrane stretch. Although the gene has been cloned and the crystal structure of the closed channel has been defined, how membrane tension causes conformational changes in MscL remains largely unknown. To identify the site where MscL senses membrane tension, we examined the function(More)
Corynebacterium glutamicum MscCG, also referred to as NCgl1221, exports glutamate when biotin is limited in the culture medium. MscCG is a homolog of Escherichia coli MscS, which serves as an osmotic safety valve in E. coli cells. Patch-clamp experiments using heterogeneously expressed MscCG have shown that MscCG is a mechanosensitive channel gated by(More)
Many free-swimming unicellular organisms show negative gravitaxis, i.e. tend to swim upward, although their specific densities are higher than the medium density. To obtain clues to the mechanism of this behavior, we examined how a mutation in motility or behavior affects the gravitaxis in Chlamydomonas. A phototaxis mutant, ptx3, deficient in membrane(More)
MscS is a mechanosensitive channel that is ubiquitous among bacteria. Recent progress in the genome projects has revealed that homologs of MscS are also present in eukaryotes, but whether they operate as ion channels is unknown. In this study we cloned MSC1, a homolog of MscS in Chlamydomonas, and examined its function when expressed in Escherichia coli.(More)
The mechanosensitive channel of small conductance (MscS) is a bacterial mechanosensitive channel that opens in response to rapid hypoosmotic stress. Since MscS can be opened solely by membrane stretch without help from any accessory protein, the lipid-protein interface must play a crucial role in sensing membrane tension. In this study, the hydrophobic(More)
Bacterial cells avoid lysis in response to hypoosmotic shock through the opening of the mechanosensitive channel MscL. Upon channel opening, MscL is thought to expand in the plane of the membrane and form a large pore with an estimated diameter of 3-4 nm. Here, we set out to analyze the closed and open structure of cell-free MscL. To this end, we(More)
A key molecule of sensing machineries essential for survival upon hypo-osmotic shock is the mechanosensitive channel. The bacterial mechanosensitive channel MscS functions directly for this purpose by releasing cytoplasmic solutes out of the cell, whereas plant MscS homologues are found to function in chloroplast organization. Here we show that the fission(More)
Ion channels form a group of membrane proteins that pass ions through a pore beyond the energy barrier of the lipid bilayer. The structure of the transmembrane segment of membrane proteins is influenced by the charges and the hydrophobicity of the surrounding lipids and the pressure on its surface. A mechanosensitive channel is specifically designed to(More)
The bacterial mechanosensitive channel MscS protects the bacteria from rupture on hypoosmotic shock. MscS is composed of a transmembrane domain with an ion permeation pore and a large cytoplasmic vestibule that undergoes significant conformational changes on gating. In this study, we investigated whether specific residues in the transmembrane and(More)