The veA gene is necessary for the negative regulation of the veA expression in Aspergillus nidulans.

The veA gene is one of the key genes in regulating sexual development of Aspergillus nidulans. During the study on the veA gene, it was observed that the veA expression level is slightly higher in a veA1 mutant than in a wild type at 37 degrees C, suggesting that the wild type veA gene is necessary for the negative regulation of the veA expression. In the veA1 mutant, the veA expression was higher than in a wild type grown at 42 degrees C but equal at 30 degrees C. Furthermore, in a veA deletion mutant having its own promoter and the N-terminus of the VeA ORF, expression of the N-terminus by the veA promoter was highly up-regulated, supporting the possibility that the veA gene is important for the negative regulation of the veA expression. Analyses of the lacZ transcript and the beta-galactosidase activity from the reporter strains in the veA1 background, which were constructed by transformation of the lacZ reporter plasmids containing the lacZ gene under the control of the intact or the truncated veA promoters from the -943 to +262 bp region, showed that the truncated promoters produced more veA transcript and higher beta-galactosidase activity than the intact one at 30 degrees C, but equal at 42 degrees C. In addition, the serial-deletion analysis of the veA promoter identified a crucial region in the promoter from -943 to -740 bp for this derepression of the veA expression. Taken together, these results indicated that the veA gene is necessary for the negative regulation of the veA expression. Moreover, the veA expression was derepressed in the light-illuminated condition, where the VeA protein is hardly transported into the nucleus.