View the Current Issue

Article

  • The EMBO Journal (2000) 19, 5782 - 5792
  • doi:10.1093/emboj/19.21.5782

Osmotic stress response in Dictyostelium is mediated by cAMP

Alexander Ott1,4, Felix Oehme2,4, Heike Keller1 and Stephan C. Schuster3

  1. Max-Planck-Institut für Biochemie, D-82152 Martinsried, Germany
  2. Present address: Bayer AG, Geschäftsbereich Pharma, D-42096 Wuppertal, Germany
  3. Present address: Max-Planck-Institut für Entwicklungsbiologie, Spemannstrasse 35, D-72076 Tübingen, Germany
  4. A.Ott and F.Oehme contributed equally to this work

Correspondence to:

Stephan C. Schuster, E-mail: stephan.schuster@tuebingen.mpg.de

Received 16 May 2000; Accepted 8 September 2000; Revised 23 August 2000

DokA, a homolog of bacterial hybrid histidine kinases, is essential for hyperosmotic stress resistance in Dictyostelium. We show that a transient intracellular cAMP signal, dependent on the presence of DokA, is generated in response to an osmotic shock. This variation of cAMP levels contributes to survival under hypertonic conditions. In contrast to the low cAMP levels observed in dokA- strains, overexpression of the receiver domain of DokA causes an increase in cAMP levels, resulting in a rapidly developing phenotype. We present biochemical and cell biological data indicating that the DokA receiver domain is a dominant-negative regulator of a phosphorelay, which controls the intracellular cAMP phosphodiesterase RegA. The activity of the DokA receiver domain depends on a conserved aspartate, mutation of which reverses the developmental phenotype, as well as the deregulation of cAMP metabolism.

  • Keywords:

    • cAMP,
    • osmotic stress,
    • phosphatases,
    • phosphorelay,
    • signal transduction