THE HYBRID HISTIDINE KINASE DOKA IS PART OF THE OSMOTIC RESPONSE SYSTEM OF DICTYOSTELIUM

We have used PCR to identify a Dictyostelium homolog of the bacterial two-component system. The gene dokA codes for a member of the hybrid h istidine kinase family which is defined by the presence of conserved a mino acid sequence motifs corresponding to an N-terminal receptor doma in, a central kinase and a C-terminal response regulator moiety. Poten tial function of the regulator domain was demonstrated by phosphorylat ion in vitro, dokA mutants are deficient in the osmoregulatory pathway , resulting in premature cell death under high osmotic stress. Under l ess stringent osmotic conditions, cells grow at a normal rate, but dev elopment at the multicellular stage is altered. dokA is a member of a family of histidine kinase-like genes that play regulatory roles in eu karyotic cell function.