The transient receptor potential channel on the yeast vacuole is mechanosensitive.
Ca2+ is released from the vacuole into the yeast cytoplasm on an osmotic upshock, but how this upshock is perceived was unknown. We found the vacuolar channel, Yvc1p, to be mechanosensitive, showing that the Ca2+ conduit is also the sensing molecule. Although fragile, the yeast vacuole allows limited direct mechanical examination. Pressures at tens of millimeters of Hg (1 mmHg = 133 Pa) activate the 400-pS Yvc1p conductance in whole-vacuole recording mode as well as in the excised cytoplasmic-side-out mode. Raising the bath osmolarity activates this channel and causes vacuolar shrinkage and deformation. It appears that, on upshock, a transient osmotic force activates Yvc1p to release Ca2+ from the vacuole. Mechanical activation of Yvc1p occurs regardless of Ca2+ concentration and is apparently independent of its known Ca2+ activation, which we now propose to be an amplification mechanism (Ca2+-induced Ca2+ release). Yvc1p is a member of the transient receptor potential-family channels, several of which have been associated with mechanosensation in animals. The possible use of Yvc1p as a molecular model to study mechanosensation in general is discussed.
Zhou
Xin-Liang
XL
Laboratory of Molecular Biology and Department of Genetics, University of Wisconsin, Madison, WI 53706, USA.
Batiza
Ann F
AF
Loukin
Stephen H
SH
Palmer
Chris P
CP
Kung
Ching
C
Saimi
Yoshiro
Y
D001483:Base Sequence; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling; D004271:DNA, Fungal / Q000235:genetics; D005800:Genes, Fungal; D006874:Hydrostatic Pressure; D040542:Mechanotransduction, Cellular; D008564:Membrane Potentials; D008954:Models, Biological; D009997:Osmotic Pressure; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D050052:TRPC Cation Channels; D014617:Vacuoles / Q000378:metabolism
D015220:Calcium Channels; D004271:DNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; D050052:TRPC Cation Channels; C446509:Yvc1 protein, S cerevisiae