PROTEIN-KINASE ACTIVITIES IN LEISHMANIA-AETHIOPICA - CONTROL BY GROWTH, TRANSFORMATION AND INHIBITORS

Promastigotes of L. aethiopica express an ectokinase activity preferri ng histone V-S as substrate. A soluble kinase activity utilizing prota mine and histone V-S, as well as a particulate fraction associated kin ase activity preferring protamine are also expressed. The soluble hist one kinase activity, but not the ectokinase, was expressed at a higher level in cells from late phases of growth, as compared to early log p hase cultures. Transformation of L. aethiopica to an amastigote-like s tage, resulted in almost complete loss of the kinase activities, with retained viability of the cells. Formycin-ATP only weakly inhibited th e kinases while effectively inhibiting cell growth and thymidine incor poration. Staurosporin efficiently blocked the kinase activities and c ell growth without affecting thymidine incorporation.