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Penicillium canescens strain F178 is a natural producer of β-galactosidase and endo-1,4-β-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. [ABSTRACT FROM AUTHOR]

The F178 strain of Penicillium canescens is a natural producer of beta-galactosidase and endo-1,4-beta-xylanase. Transcription of the genes bgaS and xylA encoding these proteins is affected by the carbon catabolite repression, which occurs in the filamentous fungi, primarily by the transcriptional repressor CreA. The creA gene of P. canescens was cloned and it was demonstrated that its own transcription is influenced by the carbon catabolic repression. Interestingly, the CreA protein remains to be nuclear localized irrespectively of the nature of the carbon source and glucose concentration in the medium. In vitro experiments revealed four CreA binding sites localized within promoter of the bgaS gene, four sites in the xylA gene promoter, and one site in the creA gene promoter. [ABSTRACT FROM AUTHOR]