Fps1p controls the accumulation and release of the compatible solute glycerol in yeast osmoregulation

Citation
Mj. Tamas et al., Fps1p controls the accumulation and release of the compatible solute glycerol in yeast osmoregulation, MOL MICROB, 31(4), 1999, pp. 1087-1104
Citations number
104
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950382X → ACNP
Volume
31
Issue
4
Year of publication
1999
Pages
1087 - 1104
Database
ISI
SICI code
0950-382X(199902)31:4<1087:FCTAAR>2.0.ZU;2-F
Abstract
The accumulation of compatible solutes, such as glycerol, in the yeast Sacc haromyces cerevisiae, is a ubiquitous mechanism in cellular osmoregulation. Here, we demonstrate that yeast cells control glycerol accumulation in par t via a regulated, Fps1 p-mediated export of glycerol. Fps1 p is a member o f the MIP family of channel proteins most closely related to the bacterial glycerol facilitators. The protein is localized in the plasma membrane. The physiological role of Fps1 p appears to be glycerol export rather than upt ake. Fps1 Delta mutants are sensitive to hypo-osmotic shock, demonstrating that osmolyte export is required for recovery from a sudden drop in externa l osmolarity, In wild-type cells, the glycerol transport rate is decreased by hyperosmotic shock and increased by hypo-osmotic shock on a subminute ti me scale. This regulation seems to be independent of the known yeast osmo-s ensing HOG and PKC signalling pathways. Mutants lacking the unique hydrophi lic N-terminal domain of Fps1p, or certain parts thereof, fail to reduce th e glycerol transport rate after a hyperosmotic shock. Yeast cells carrying these constructs constitutively release glycerol end show a dominant hypero smosensitivity, but compensate for glycerol loss after prolonged incubation by glycerol overproduction. Fps1p may be an example of a more widespread c lass of regulators of osmoadaptation, which control the cellular content an d release of compatible solutes.