[Serine/threonine type protein kinase activity in cell-free extracts of Streptomyces lividans]

Cell-free extracts of Streptomyces lividans prepared at the physiological ionic strength from the early logarithmic phase culture showed an endogenous protein kinase activity. Incubation of the salt soluble fraction of S.lividans with [gamma-32P]ATP led to incorporation of the labelled phospate into 6 to 7 polypeptide chains of 12-100 kDa. Addition of heparine, polylysine, spermine, phosphatidylserine, kanamycin, cAMP and cGMP did not change the spectrum or level of the polypeptide phosphorylation in the extract while Ca2+ ions stimulated the protein phosphorylation. It was shown that the protein kinase(s) catalyzed binding of the phosphate groups to the serine and thereonine residues in the polypeptides with M(r) 100 and 35 kDa.