Cloning and molecular analysis of the Aspergillus terreus arg1 gene coding for an ornithine carbamoyltransferase

An Aspergillus terreus gene (arg1) encoding ornithine carbamoyltransferase (OCTase) has been cloned and sequenced. The deduced amino acid sequence contains a signal peptide suggestive of a mitochondrial location for the A. terreus enzyme. Alignment of the A. terreus OCTase sequence with other OCTases revealed the presence of conserved regions. Northern analysis indicates that arg1 expression is regulated at the level of transcription and that transcription of the arg1 gene is not markedly affected by arginine sufficiency. However, histidine starvation effected by 3-amino-1,2,4-triazole increased transcription of the arg1 gene, indicating cross-pathway regulation of OCTase synthesis in A. terreus.