Figure 11

Model for the function of PhLP1, GNB1 and GNG1. GNB1, GNG1 and PhLP1 integrate signals received from the light response pathway and the heterotrimeric G-protein pathway, which predominantly transmits nutrient signals. The different transcript levels of genes between light and darkness in one strain (described as light responsiveness) of numerous genes, including 99 glycoside hydrolase (GH) encoding genes, is dampened by GNB1, GNG1 and PhLP1. Hence, GNB1, GNG1 and PhLP1 are assumed to transfer a positive light signal to the (presumably indirectly regulated) respective target genes, keeping their transcript levels elevated to the same extent as in darkness. A clear negative effect of ENV1 on phlp1 was observed, but this effect is not due to the regulation of ENV1 by BLR1 and BLR2, as they do not significantly alter the transcription of gnb1, gng1 or phlp1. Phenotypic effects of the deletion strains lacking phlp1, gnb1 and gng1 include conidiation and cellulase production, while sexual development was only influenced by GNB1 and PhLP1. The targets of GNB1, GNG1 and PhLP1 (i.e. genes differentially regulated in the deletion strains compared to the wild type) are predominantly found upon cultivation in light (13 genes upregulated, 628 genes downregulated) in contrast to a considerably smaller number in darkness (42 genes upregulated, 7 genes downregulated).