View the Current Issue

Article

  • The EMBO Journal (2008) 27, 2064 - 2076
  • doi:10.1038/emboj.2008.131

Published online: 17 July 2008

Regulation of contractile vacuole formation and activity in Dictyostelium

Fei Du1, Kimberly Edwards1,a, Zhouxin Shen1, Binggang Sun1,b, Arturo De Lozanne2, Steven Briggs1 and Richard A Firtel1

  1. Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
  2. Section of Molecular Cell & Developmental Biology, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA

Correspondence to:

Richard A Firtel, Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, Natural Sciences Building Room 6316, 9500 Gilman Drive, La Jolla, CA 92093-0380, USA. Tel.: +1 858 534 2788; Fax: +1 858 822 5900; E-mail: rafirtel@ucsd.edu

aPresent address: Department of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA

bPresent address: Johnson & Johnson Pharmaceutical Research and Development, San Diego, CA 92121, USA

Received 24 February 2008; Accepted 16 June 2008

The contractile vacuole (CV) system is the osmoregulatory organelle required for survival for many free-living cells under hypotonic conditions. We identified a new CV regulator, Disgorgin, a TBC-domain-containing protein, which translocates to the CV membrane at the late stage of CV charging and regulates CV–plasma membrane fusion and discharging. disgorgin- cells produce large CVs due to impaired CV–plasma membrane fusion. Disgorgin is a specific GAP for Rab8A-GTP, which also localizes to the CV and whose hydrolysis is required for discharging. We demonstrate that Drainin, a previously identified TBC-domain-containing protein, lies upstream from Disgorgin in this pathway. Unlike Disgorgin, Drainin lacks GAP activity but functions as a Rab11A effector. The BEACH family proteins LvsA and LvsD were identified in a suppressor/enhancer screen of the disgorgin- large CV phenotype and demonstrated to have distinct functions in regulating CV formation. Our studies help define the pathways controlling CV function.

  • Keywords:

    • BEACH proteins,
    • contractile vacuole,
    • Dictyostelium,
    • Rab,
    • RabGAP