A GATA-type transcription factor AcAREB for nitrogen metabolism is involved in regulation of cephalosporin biosynthesis in Acremonium chrysogenum.

Abstract

In filamentous fungi, nitrogen metabolism is repressed by GATA-type zinc finger transcription factors. Nitrogen metabolite repression has been found to affect antibiotic production, but the mechanism is still poorly understood. AcareB, encoding a homologue of fungal GATA-type regulatory protein, was cloned from Acremonium chrysogenum. Gene disruption and genetic complementation demonstrated that AcareB plays a key role in utilization of ammonium, glutamine and urea. In addition, significant reduction of cephalosporin production in the AcareB disruption mutant indicated that AcareB is important for cephalosporin production. In consistence with it, the transcriptional level of cephalosporin biosynthetic genes was significantly decreased in the AcareB disruption mutant. Electrophoretic mobility shift assay showed that AcAREB directly bound to the intergenic regions of pcbAB-pcbC, cefD1-cefD2 and cefEF-cefG. Sequence analysis showed that all the AcAREB binding sites contained the consensus GATA elements. AcareB is negatively autoregulated during cephalosporin production. Moreover, another GATA zinc-finger protein encoded by AcareA positively regulates the transcription of AcareB. However, AcareB does not regulate the transcription of AcareA. These results indicated that AcAREB plays an important role in both regulation of nitrogen metabolism and cephalosporin production in A. chrysogenum.