Involvement of protein kinase C in the response of Neurospora crassa to blue light

As a first step towards understanding the process of blue light perception, and the signal transduction mechanisms involved, in Neurospora crassa we h ave used a pharmacological approach to screen a wide range of second messen gers and chemical compounds known to interfere with the activity of well-kn own signal transducing molecules in vivo. We tested the influence of these compounds on the induction of the al-3 gene, a key step in light-induced ca rotenoid biosynthesis. This approach has implicated protein kinase C (PKC) as a component of the light transduction machinery. The conclusion is based on the effects of specific inhibitors (calphostin C and chelerythrine chlo ride) and activators of PKC (1,2-dihexanoyl-sn-glycerol). During vegetative growth PKC may be responsible for desensitization to light because inhibit ors of the enzyme cause an increase in the total amount of mRNA transcribed after illumination. PKC is therefore proposed here to be an important regu lator of transduction of the blue light signal, and may act through modific ation of the protein White Collar-1, which we show to be a substrate for PK C in N. crassa.