Cloning, characterization of the acyl-CoA:6-amino penicillanic acid acyltransferase gene of Aspergillus nidulans and linkage to the isopenicillin N synthase gene.

The penDE gene encoding acyl-CoA:6-amino penicillanic acid acyltransferase (AAT), the last enzyme of the penicillin biosynthetic pathway, has been cloned from the DNA of Aspergillus nidulans. The gene contains three introns which are located in the 5' region of the open reading frame. It encodes a protein of 357 amino acids with a molecular weight of 39,240 Da. The penDE gene of A. nidulans shows 73% similarity at the nucleotide level with the penDE gene of Penicillium chrysogenum. The A. nidulans gene was expressed in P. chrysogenum and complemented the AAT deficiency of the non-producer mutants of P. chrysogenum, npe6 and npe8. The penDE gene of A. nidulans is linked to the pcbC gene, which encodes the isopenicillin N synthase, as also occurs in P. chrysogenum. Both genes show the same orientation and are separated by an intergenic region of 822 nucleotides.