Identification of the novel penicillin biosynthesis gene aatB of Aspergillus nidulans and its putative evolutionary relationship to this fungal secondary metabolism gene cluster

Abstract

The final step of penicillin biosynthesis in the filamentous fungus Aspergillus nidulans is catalysed by isopenicillin N acyltransferase encoded by the aatA gene. Because there is no bacterial homologue, its evolutionary origin remained obscure. As shown here, disruption of aatA still enabled penicillin production. Genome mining led to the discovery of the aatB gene (AN6775.3) which has a similar structure and expression pattern as aatA. Disruption of aatB resulted in a reduced penicillin titre. Surface plasmon resonance analysis and Northern blot analysis indicated that the promoters of both aatA and aatB are bound and regulated by the same transcription factors AnCF and AnBH1f. In contrast..