Multiple transcriptional regulators play important roles in the coordination of developmental processes, including asexual and sexual development, and secondary metabolism in the filamentous fungus Aspergillus nidulans. In the present study, we characterized a novel putative C₂H₂-type transcription factor (TF), RocA, in relation to development and secondary metabolism. Deletion of rocA increased conidiation and caused defective sexual development. In contrast, the overexpression of rocA exerted opposite effects on both phenotypes. Additionally, nullifying rocA resulted in enhanced brlA expression and reduced nsdC expression, whereas its overexpression exerted the opposite effects. These results suggest that RocA functions as a negative regulator of asexual development by repressing the expression of brlA encoding a key asexual development activator, but as a positive regulator of sexual development by enhancing the expression of nsdC encoding a pivotal sexual development activator. Deletion of rocA increased the production of sterigmatocystin (ST), as well as the expression of its biosynthetic genes, aflR and stcU. Additionally, the expression of the biosynthetic genes for penicillin (PN), ipnA and acvA, and for terrequinone (TQ), tdiB and tdiE, was increased by rocA deletion. Thus, it appears that RocA functions as a negative transcriptional modulator of the secondary metabolic genes involved in ST, PN, and TQ biosynthesis. Taken together, we propose that RocA is a novel transcriptional regulator that may act either positively or negatively at multiple target genes necessary for asexual and sexual development and secondary metabolism.

中文翻译：

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假定的C2H2转录因子RocA是构巢曲霉中发育和次级代谢的新型调节剂。

多种转录调节因子在协调无性和有性发育以及丝状真菌构巢曲霉的次级代谢等发育过程中起重要作用。在本研究中，我们表征了新型推定的C ₂ H ₂型转录因子（TF）RocA，与发育和次级代谢有关。rocA的删除增加了分娩，并导致不良的性发育。相反，rocA的过表达对两种表型产生相反的作用。此外，使rocA无效会使brlA表达增强，并降低nsdC表达，而其过表达发挥相反的作用。这些结果表明，RocA通过抑制编码关键性无性发育激活剂的brlA的表达而充当无性发育的负调节剂，但通过增强编码关键性性发育激活剂的nsdC的表达而作为性发育的正性调节剂。rocA的缺失增加了其菌丝体蛋白（ST）的产生，并增加了其生物合成基因aflR和stcU的表达。此外，青霉素（PN），ipnA和acvA以及terrequinone（TQ），tdiB的生物合成基因的表达rocA缺失使tdiE和tdiE增加。因此，似乎RocA充当了参与ST，PN和TQ生物合成的次级代谢基因的负转录调节子。综上所述，我们认为RocA是一种新型的转录调节因子，可对无性和有性发育以及继发代谢所必需的多个靶基因产生正向或负向作用。