Regulation of Expression of a Cytochrome P450 Enzyme System in Aspergillus niger

Hans (J.).M. van den Brnk, Cees.A.M.J.J van den Hondel and Robert.F.M. van Gorcom

Author address: 

TNO Nutrition and Food Research, Department of Molecular Genetics and Gene technology, P.O. box 5815, 2280 HV Rijswijk, the Netherlands


Cytochrome P450 enzyme systems comprise two elements; cytochrome P450 reductase (CPR), a generally acting electron donor and the reaction specific cytochrome P450 enzyme. In previous work we have identified the A.niger cytochrome P450 gene encoding benzoate para-hydroxylase (bpha) and the gene encoding cytochrome P450 reductase (cprA). Expression of both genes was shown to be regulated at the transcriptional level by benzoate. However, some indications were obtained that regulation also might occur at post-transcriptional level. To study the exact mechanism underlying the regulation of gene expression of both genes, the gene control region of both genes were fused to a reporter gene followed by generation of progressive deletions. Using this strategy we were able to identify regions in both gene control regions involved in benzoate dependent induction of gene expression. In gel mobility shift assays, using specific DNA fragments obtained from both promoters, we were able to further localize these Benzoate Responsive Elements (BRE's). Another mechanism involved in regulation of the BPH enzyme system is the use of different promoters'). Clear differences in mRNA size was observed between cprA and bphA mRNA obtained from induced and from non-induced mycelium. Using 5'-RACE we were able to determine the different transcription start points. 1)Promoter is defined as the part of the gene expression control region where the general transcription factors and the RNA polymerase assemble

abstract No: 


Full conference title: 

    • ECFG 3rd (1996)