Calmodulin-dependent protein phosphorylation during conidial germination and growth of Neurospora crassa

Abstract

Conidial germination in Neurospora crassa was inhibited by the anticalmodulin (CaM) agents calmidazolium (CaMZ) and trifluoperazine (TFP), indicating the importance of CaM-dependent events during vegetative growth. An increase in intracellular CaM concentration, observed during conidial germination, was associated with enhanced incorporation of [3H]phenylalanine into CaM and increased CaM-dependent protein kinase activity. Phosphorylation of two proteins (71 and 25 kDa) during conidial germination, and of four proteins (71, 47, 38 and 32 kDa) during hyphal elongation was noted to be CaM-dependent since these phosphorylations were inhibited in vitro by CaMZ. The possible regulatory functions of CaM during conidial germination are discussed in relation to phosphorylation of specific proteins during vegetative growth in N. crassa.