Differential expression of polygalacturonase-encoding genes from Penicillium griseoroseum in different carbon sources

A second polygalacturonase-encoding gene (pgg2) of Penicillium griseoroseum was cloned and consists of an opening reading frame of 1107 bp after removal of two introns. The gene encodes a protein of 369 amino acids with a predicted molecular mass of 38.3 kDa. The deduced protein sequence exhibited high homology with other fungal endopolygalacturonases. A polymerase chain reaction (PCR)-based strategy was used to study the expression patterns of pgg1 and pgg2 genes under different culture conditions and our results show that both genes are regulated by the carbon source at the transcriptional level. The pgg1 transcript was detected at 76 h of fungal growth in pectin while the pgg2 transcript was also induced by sucrose. The addition of yeast extract to glucose medium abolished the repressive effect of glucose, suggesting that the transcription of these genes is controlled by different mechanisms.