Effect of protein kinase inhibitors on protein phosphorylation and germination of aerial spores from Streptomyces coelicolor.

In vitro phosphorylation reaction using extracts prepared from cells in the exponential phase of growth and aerial spores of Streptomyces coelicolor displayed the presence of multiply phosphorylated proteins. Effect of protein kinase inhibitors (PKIs) (geldanamycin, wortmannin, apigenin, genistein, roscovitine, methyl 2,5-dihydroxycinnamate, rapamycin, staurosporine) was determined on protein phosphorylation and on germination of spores. The in vitro experiments showed differences in phosphoprotein pattern due to the presence of PKIs. Cultivation of aerial spores with PKIs led to a significant delay in germ tube emergence and filament formation. However, none of the tested PKIs completely blocked the germination process. These results indicate that protein kinases of spores form complex networks sharing common modulating site that plays an important role in proper timing of early developmental events.