The Ded1 DEAD box helicase interacts with Chk1 and Cdc2

Ded1 is a fission yeast DEAD box protein involved in translation. We isolated Ded1 in a screen for multi-copy suppressors of a cold-sensitive, loss-of-function mutant of the cyclin-dependent kinase Cdc2. The checkpoint protein kinase Chk1, required for cell cycle arrest in response to DNA damage, was also isolated in this screen. Ded1 interacts with Chk1 in a two-hybrid screen, and this physical interaction can be recapitulated in Schizosaccharomyces pombe. The Ded1 polypeptide is modified in response to heat shock and depletion of carbon source. These two stressors appear to cause different modifications. Thus, the Ded1 protein appears to respond to particular types of cellular stress and may influence the activity of Cdc2 as a result.