Involvement of protein kinase C in lignin peroxidase expression in oxygenated cultures of the white rot fungus Phanerochaete chrysosporium

Abstract

Hydroxyl radicals (OH ) were previously hypothesized as the principal ROS triggering lip-H2 expression in liquid cultures of Phanerochaete chrysosporium, through signal transduction. We therefore focused on determining the relationship between protein kinase C (PKC), ROS and LIP-H2. Significantly lower PKC activity was measured in high-LIP-producing (oxygenated) vs. low-LIP-producing (aerated—grown with free exchange of atmospheric air) cultures. In oxygenated cultures, inactivation of PKC activity by calphostin C, staurosporin or H7 caused significant elevation in lip-H2 and also in MnSOD1 expression. Stimulation of PKC by phorbol 12-myristate 13-acetate (PMA) caused the reverse effect. Significantly low levels of lip-H2 expression were detected when O 2 −, H 2O 2 or OH were scavenged by 4,5-dihydroxy-1,3-benzene disulfonic acid (Tiron), pyruvate or dimethylsulfoxide (DMSO), whether the level of PKC was normal, stimulated or inactivated. In situ generation of OH , via addition of Fenton reagents to aerated cultures, reduced pkc expression. In contrast, OH scavenging stimulated pkc expression. This work suggests that due to high OH levels, fungal cells activate a complex defensive system which regulates the levels of Fenton components by repressing PKC and stimulating LIP, MnSOD1 and catalase.