THE PENICILLIN REGULATOR PENR1 OF ASPERGILLUS-NIDULANS IS A HAP-LIKE TRANSCRIPTIONAL COMPLEX

In Aspergillus nidulans, a DNA-binding complex, PENR1, was shown to bi nd to two CCAAT-box-containing DNA elements located in the promoter re gions of the bidirectionally oriented penicillin biosynthesis genes ac vA and ipnA, and of the aat promoter. Here, partial purification of PE NR1 and western blotting using anti-HAPC sera indicated that the previ ously identified HAPC protein, which was suggested to be part of the C CAAT-binding complex AnCF, is also part of PENR1. This was confirmed b y band shift assays using protein extracts of Delta hapC strain which exhibited no PENR1 DNA-binding activity. Supershift assays and immunop recipitation analysis using anti-HAPC sera provided evidence that HAPC is pari or the PENR1 complex. In Delta hapC strains, penicillin produ ction was reduced, as was expression of both an ipnA-lacZ and aat-lacZ gene fusion. Hence, HAPC-containing PENR1 appears to act as an activa tor on ipnA and aat expression. However, deletion of hapC had little e ffect on acvA expression during a fermentation run in fermentation med ium. Previous results which had shown that specific deletion of the PE NR1-binding site between acvA and ipnA resulted in a strong increase o f expression of an acv-uidA gene fusion, together vith the present dat a. suggest the possibility of the existence of a repressor protein tha t binds close to or overlaps the PENR1-binding site, It is also shown that binding of PENR1 induced bending of a DNA fragment spanning the P ENR1-binding sits between acv1 and ipnA in vitro.