Cloning, characterisation and regulation of the ornithine transaminase (otaA) gene of Aspergillus nidulans

The ornithine transaminase (otaA) gene of Aspergillus nidulans has been clo ned by transformation of the A. nidulans pro(-)ota(-) mutant strain with a cosmid gene library. The otaA gene contains two introns and potentially cod es for a 453-aa-long protein. The deduced amino-acid sequence is homologous to known ornithine transaminases from Saccharomyces cerevisiae. Plasmodium falciparum, Vigna aconitifolia, rat, mouse and man, particularly in the py ridoxal phosphate-binding domain. The expression of the otaA gene is specif ically induced by arginine, and is also under the control of nitrogen-metab olite and carbon-catabolite repression. Regulation of the gene occurs at bo th transcriptional and post-transcriptional levels. The promoter region of otaA contains putative AREA and CREA binding-sites. Fusion proteins contain ing AREA or CREA DNA-binding domains bind some of these sites. CREA binding -sites correspond very well to the CREA-binding consensus sequence which is SYGGRG. AREA binding-sites are composed of GATT sequences which are not ty pical binding sites for the GATA - binding family of transcription factors.