title: Osmosensing by bacteria.
abstract: Osmosensors are proteins that sense environmental osmotic pressure. They mediate or direct osmoregulatory responses that allow cells to survive osmotic changes and extremes. Bacterial osmosensing transporters sense high external osmotic pressure and respond by mediating organic osmolyte uptake, hence cellular rehydration. Detailed studies of osmosensing transporters OpuA, BetP, and ProP suggest that they sense and respond to different osmotic pressure-dependent cellular properties. These studies also suggest that each protein has a cytoplasmic osmosensory or osmoregulatory domain, but that these domains differ in structure and function. It is not yet clear whether each transporter represents a distinct osmosensory mechanism or whether different research groups are approaching the same mechanism by way of different paths. Principles emerging from this research will apply to other osmosensors, including those that initiate signal transduction cascades in prokaryotes and eukaryotes.
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada. jwood@uoguelph.ca
authors.forename: Janet M
authors.initials: JM
authors.lastname: Wood
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000502:physiology*; D000251:Adenosine Triphosphatases / Q000502:physiology*; D020346:Aquaporins / Q000502:physiology; D018407:Bacterial Physiological Phenomena; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D001622:Betaine / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000502:physiology*; D027682:Cation Transport Proteins / Q000502:physiology; D048230:Corynebacterium glutamicum / Q000737:chemistry / Q000502:physiology; D004573:Electrolytes / Q000494:pharmacology; D004926:Escherichia coli / Q000502:physiology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism; D013294:Lactococcus lactis / Q000502:physiology; D008565:Membrane Proteins / Q000502:physiology; D008954:Models, Biological; D009997:Osmotic Pressure; D011092:Polyethylene Glycols / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011510:Proteolipids / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D027981:Symporters / Q000737:chemistry / Q000502:physiology*; D014867:Water / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D020346:Aquaporins; D001426:Bacterial Proteins; C101652:BetP protein, Corynebacterium glutamicum; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D004573:Electrolytes; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C079244:ProP protein, E coli; D011510:Proteolipids; D027981:Symporters; C106425:aqpZ protein, E coli; C020485:proteoliposomes; D014867:Water; D018698:Glutamic Acid; D001622:Betaine; D011092:Polyethylene Glycols; D000251:Adenosine Triphosphatases; C058166:potassium translocating Kdp-ATPase, E coli; C412743:OpuA protein, Lactococcus lactis; D011188:Potassium