arcA, the regulatory gene for the arginine catabolic pathway in Aspergillus nidulans

Abstract

We have cloned and analysed the arcA gene which encodes a transcriptional activator necessary for the high-level expression of two genes for enzymes of the arginine catabolic pathway in Aspergillus nidulans: agaA (for arginase) and otaA (for ornithine transaminase, OTAse). Here we present complete genomic and cDNA sequences for, and describe the pattern of expression of, the arcA gene. This gene contains one intron and encodes a polypeptide of 600 amino acids. The deduced protein belongs to the family of Zn(2)Cys(6) fungal regulatory proteins. ARCA is the first known protein of this family that has glycine instead of the conserved proline at the fifth position in the second, six-residue, loop of the Zn cluster domain. We have established that transcription of the arcA gene is not self-regulated and does not depend on arginine. Two mutations in arcA, one gain-of-function and one loss-of-function, have been sequenced and the effects of these mutations on the expression of the agaA gene at the transcriptional level are reported.

Divergent Targets of Aspergillus fumigatus AcuK and AcuM Transcription Factors during Growth In Vitro versus Invasive Disease

“…One of these genes, Afu5g11070, may have a functional connection to iron acquisition. Its A. nidulans ortholog, arcA, specifies an activator of arginine catabolic genes (34). The arginine breakdown product ornithine is essential for siderophore synthesis in aspergilli (13,35).…”

The GATA factors AREA and AREB together with the co-repressor NMRA, negatively regulate arginine catabolism in Aspergillus nidulans in response to nitrogen and carbon source

“…In a transamination reaction OAT converts ornithine to glutamic-5-semialdehyde transferring the a-amino group from this a-amino acid to a-ketoglutarate which is converted to glutamate. Transcription of agaA and otaA is induced by arginine and dependent on the specific activator ARCA (Empel et al, 2001). Both genes are also subject to nitrogen metabolite and carbon catabolite repression (Bartnik et al, 1973b).…”

Characterization of the oat1 gene of Penicillium chrysogenum encoding an ω-aminotransferase: induction by L-lysine, L-ornithine and L-arginine and repression by ammonium

“…5). Since this amino acid is catabolized to ornithine and urea by arginase (Empel et al 2001) and ornithine is not utilized as nitrogen source by the disrupted mutants, the residual growth of the mutants is likely to be due to utilization of urea as a poor nitrogen source.…”

“…The 8-bp direct repeat in the P. chrysogenum oat1 gene is also similar to the direct repeat in the promoters of CAR1 and CAR2 in S. cerevisiae, and in the aga gene of A. nidulans (Empel et al 2001). A comparison of the sequences in the direct repeats in the promoters of all these genes with that of P. chrysogenum oat1 gene allows us to define more precisely the putative ArcA-binding region (Fig.…”

“…b Alignment of direct repeat sequences in the P. chrysogenum oat1 promoter with the ArcA-binding sequences in the promoters of CAR1, CAR2, ARG3, and ARG5, 6 of S. cerevisiae and otaA of A. nidulans. The consensus 5-nt motif is shaded (Empel et al 2001). This transcription factor binds as a dimer to the direct repeats shown in Fig.…”