The Dictyostelium LvsA protein is localized on the contractile vacuole and is required for osmoregulation.
LvsA is a Dictyostelium protein that is essential for cytokinesis and that is related to the mammalian beige/LYST family of proteins. To better understand the function of this novel protein family we tagged LvsA with GFP using recombination techniques. GFP-LvsA is primarily associated with the membranes of the contractile vacuole system and it also has a punctate distribution in the cytoplasm. Two markers of the Dictyostelium contractile vacuole, the vacuolar proton pump and calmodulin, show extensive colocalization with GFP-LvsA on contractile vacuole membranes. Interestingly, the association of LvsA with contractile vacuole membranes occurs only during the discharge phase of the vacuole. In LvsA mutants the contractile vacuole becomes disorganized and calmodulin dissociates from the contractile vacuole membranes. Consequently, the contractile vacuole is unable to function normally, it can swell but seems unable to discharge and the LvsA mutants become osmosensitive. These results demonstrate that LvsA can associate transiently with the contractile vacuole membrane compartment and that this association is necessary for the function of the contractile vacuole during osmoregulation. This transient association with specific membrane compartments may be a general property of other BEACH-domain containing proteins.
Gerald
Noel J
NJ
Section of Molecular Cell & Developmental Biology and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
Siano
Michael
M
De Lozanne
Arturo
A
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D002147:Calmodulin / Q000378:metabolism; D002455:Cell Division; D002462:Cell Membrane / Q000378:metabolism; D004023:Dictyostelium / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D009154:Mutation; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism*; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011995:Recombination, Genetic; D013997:Time Factors; D014867:Water / Q000378:metabolism*; D014882:Water-Electrolyte Balance
D002147:Calmodulin; D008164:Luminescent Proteins; C403705:LvsA protein, Dictyostelium; D011506:Proteins; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D014867:Water; D049452:Green Fluorescent Proteins; D000251:Adenosine Triphosphatases