The Aspergillus nidulans homoaconitase gene lysF is negatively regulated by the multimeric CCAAT-binding complex AnCF and positively regulated by GATA sites

Abstract

In beta-lactam-antibiotic-producing fungi, such as Aspergillus (Emericella) nidulans, L-alpha-aminoadipic acid is the branching point of the lysine and penicillin biosynthesis pathways. To obtain a deeper insight into the regulation of lysine biosynthesis genes, the regulation of the A. nidulans lysF gene, which encodes homoaconitase, was studied. Band-shift assays indicated that the A. nidulans multimeric CCAAT-binding complex AnCF binds to two of four CCAAT motifs present in the lysF promoter region. AnCF consists at least of three different subunits, designated HapB, HapC, and HapE. In both a delta hapB and a delta hapC strain, the expression of a translational lysF-lacZ gene fusion integrated in single copy at the chromosomal argB gene locus was two to three-fold higher than in a wild-type strain. These data show that AnCF negatively regulates lysF expression. The results of Northern blot analysis and lysF-lacZ expression analysis did not indicate a lysine-dependent repression of lysF expression. Furthermore, mutational analysis of the lysF promoter region revealed that two GATA sites matching the GATA consensus sequence HGATAR positively affected lysF-lacZ expression. Results of Northern blot analysis also excluded that the global nitrogen regulator AreA is the responsible trans-acting GATA-binding factor.

Regulation of transcription of cellulases- and hemicellulases-encoding genes in Aspergillus niger and Hypocrea jecorina (Trichoderma reesei)

“…On the other hand, CCAAT boxes in filamentous fungi showing repressing functions (e.g. the lysF promoter [A. nidulans] and the xyn2 promoter [H. jecorina]) have also been observed (Weidner et al 2001;Würleitner et al 2003). The induction-specific complex is counteracted by an uncharacterised DNAbinding protein (complex) binding to a 5′-AGAA-3′ box immediately upstream of the XAE (Stricker et al, manuscript in preparation).…”

Transcriptional Regulation of xyn2 in Hypocrea jecorina

“…However, in the xyn2 promoter, a similar mutation in the CCAAT-box of XAE resulted in a small but reproducible increase both in basal and in induced xyn2 gene transcription, indicating that the Hap2/3/5 complex partially mediates xyn2 repression. Negative regulation by the human Hap homologue NF-Y has been observed in some cases (e.g., topoisomerase II␣, the type II transforming growth factor ␤ receptor, and the varicella-zoster virus ORF62 [12,13,21]) and, more recently, also for the lysF promoter of the fungus A. nidulans (37). In hematopoietic cells, repression of the proteintyrosine phosphatase gene by NF-Y was shown to be dependent on its interaction with the histones (40).…”

Regulation of freA , acoA , lysF , and cycA Expression by Iron Availability in Aspergillus nidulans

“…Remarkably, the promoter region of lysF contains several GATA motifs which potentially represent SREA binding sites. But since mutational analysis showed that at least two of these GATA sites mediate a positive effect on lysF expression, a direct involvement of the repressor SREA seems to be doubtful (31).…”