A PROTEIN-KINASE C-LIKE ACTIVITY INVOLVED IN THE CHEMOTACTIC RESPONSEOF DICTYOSTELIUM-DISCOIDEUM

During the developmental life cycle of the cellular slime mould Dictyo stelium discoideum cells aggregate in response to pulses of extracellu lar cAMP. This chemotactic agent stimulates a number of signalling pat hways in the cell including the activation of a phospholipase C activi ty leading ito the transient generation of inositol 3,4,5-trisphosphat e and diacylglycerol. The role of diacylglycerol in chemotactic respon se and development of Dictyostelium is not known. We have evidence to suggest that two protein kinase C-like enzymes exist in Dictyostelium due to the different cellular responses to two inhibitors specific for protein kinase C. One enzyme is preferentially sensitive to D-erythro -sphingosine, a diacylglycerol analogue, and is required for growth. A second is preferentially inhibited by bisindolylmaleimide GF109203X a nd is required for chemotaxis. We have identified protein kinase C-lik e kinase activity in Dictyostelium cell extracts which appears as the cells aggregate. This activity is stimulated by diacylglycerol, especi ally biologically relevant diacylglycerol species, and phosphorylates a peptide substrate which is an efficient substrate for mammalian prot ein kinase Cs. This activity is a candidate for the effector of diacyl glycerol generated during the aggregative phase of Dictyostelium devel opment and defines a role for diacylglycerol in the chemotactic respon se. (C) 1997 Elsevier Science B.V.