Mutational analysis of carbon catabolite repression in filamentous fungus Penicillium canescens

Penicillium canescens strain F178 is a natural producer of beta-galactosidase and endo-1,4-beta-xylanase. Transcription of bgaS and xylA genes coding these proteins is subject to carbon catabolite repression. A system of direct selection of P. canescens regulatory mutants has been developed. Two mutant strains from the obtained collection have been studied in detail. Both mutations have been shown to be complemented by the creA gene coding global regulator of carbon catabolite repression in filamentous fungi. Also, creA (-) alleles contain frameshift mutations in the CreA C-domain. It has been found that the xylA gene is derepressed in mutants at the transcription level in the presence of D-glucose. The transcription of the creA gene in mutants is also derepressed proving the effect of autoregulation for this gene.