CLONING AND MOLECULAR ANALYSIS OF THE ASPERGILLUS-TERREUS ARG1 GENE CODING FOR AN ORNITHINE CARBAMOYLTRANSFERASE

An Aspergillus terreus gene (argl) encoding ornithine carbamoyltransfe rase (OCTase) has been cloned and sequenced. The deduced amino acid se quence contains a signal peptide suggestive of a mitochondrial locatio n for the A. terreus enzyme. Alignment of the A. terreus OCTase sequen ce with other OCTases revealed the presence of conserved regions. Nort hern analysis indicates that argl expression is regulated at the level of transcription and that transcription bf the argl gene is not marke dly affected by arginine sufficiency. However, histidine starvation ef fected by 3-amino-1,2,4-triazole increased transcription of the argl g ene, indicating cross-pathway regulation of OCTase synthesis in A. ter reus.