Project description:Acremonium chrysogenum is the industrial producer of cephalosporin C. We isolated a mutant (AC554) from a T-DNA inserted library of A. chrysogenum. AC554 exhibited reduced conidiation and lack of cephalosporin C production. In consistent, the transcription of cephalosporin biosynthetic genes pcbC and cefEF was obviously decreased in AC554. TAIL-PCR and sequence analysis indicated that a T-DNA was inserted in the upstream of an open reading frame (ORF) which was designated AcmybA. Sequence analysis indicated that AcmybA encodes a novel Myb domain containing transcriptional factor. Observation of red fluorescence protein (RFP) tagged AcMybA showed that AcMybA is naturally located in the nuclear of A. chrysogenum. Transcription analysis demonstrated that AcmybA was overexpressed in AC554. In contrast with AC554, the AcmybA deleted mutant (DAcmybA) overproduced conidia in LPE medium and increased cephalosporin production during fermentation. To determine the genes under the influence of AcmybA, we sequenced and compared the transcriptome of DAcmybA, AC554 and the wild-type strain at different developmental stages. Results confirmed the repression of AcMybA on the key conidiation regulatory gene AcbrlA and the cephalosporin biosynthetic genes. Among the targets of AcMybA, 10 putative regulatory genes were selected and overexpressed in A. chrysogenum. Taken together, our results indicate that AcMybA negatively regulates conidiation and cephalosporin production in A. chrysogenum.
