Regulation of pyrimidine salvage in Aspergillus nidulans: A role for the major regulatory gene areA mediating nitrogen metabolite repression

Abstract

The synthesis of thymine 7-hydroxylase, an alpha-ketoglutarate dependent dioxygenase, is subject both to nitrogen metabolite repression and to oxygen repression, while synthesis of the other pyrimidine salvage pathway dioxygenase, pyrimidine deoxyribonucleoside 2'-hydroxylase, is subject to neither. are A300, an allele of the positive acting regulatory gene are A mediating nitrogen metabolite repression in Aspergillus nidulans, considerably elevates levels of thymine 7-hydroxylase, probably alleviating at least partly both nitrogen metabolite repression and oxygen repression. are A300 has little or no effect on levels of pyrimidine deoxy-ribonucleoside 2'-hydroxylase but does elevate net uptake capacities for thymine, thymidine and deoxyuridine two-fold. are A300 was selected as allowing thymine to supplement a pyrimidine auxotrophy and was found to allow supplementation by thymidine, other pyrimidine nucleosides and pyrimidine salvage intermediates as well. This is the first reported evidence for are A control over an activity(-ies) not directly concerned with nitrogen source utilization.

The bZIP Protein MeaB Mediates Virulence Attributes in Aspergillus flavus

“…However, because the pyrG gene located to a different position in the KD strain than in the deletion strains, yet the KD mutant still required supplementation and the OE::meaB strain (where pyrG located to the same region as in the ΔmeaB strains) did not require supplementation, it is possible that MeaB could be involved in pyrimidine metabolism. Although there is no report for a requirement for MeaB in pyrimidine synthesis in the literature, another nitrogen global regulator, AreA, has been connected with pyrimidine metabolism [38]. Whatever the mechanism underlying the requirement for supplementation in growth medium, there was no observable impact on growth of the deletion strain on seed.…”

ADHII in Aspergillus nidulans Is Induced by Carbon Starvation Stress

“…Nitrogen metabolite repression leads to repression of enzymes and permeases involved in the utilization of nitrogen sources other than ammonium or l-glutamine, and this is mediated by AreA. There are a few examples of genes involved in C source utilization that are under AreA control, e.g., the gene for thymine-7-hydroxylase involved in the pyrimidine salvage pathway (Shaffer et al, 1984) and the gene for pyruvate decarboxylase (Lockington et al, 1997). GATAR sequences have been shown to be potential targets for AreA (Merika and Orkin, 1993) and there are two such sequences at Ϫ100 and Ϫ135 from the start of translation in alcB.…”

Direct analysis of native and chimeric GATA specific DNA binding proteins from Aspergillus nidulans

“…A second possibility is that a GATA binding activity may have a role in oxygen repression. One areA allele, designated areA300, was selected as leading to derepression of the pyrimidine salvage pathway which is subject to oxygen repression [53]. The areA300 allele leads to the synthesis of an AREA molecule with two zinc finger domains, due to the tandem duplication of 139 amino acids [54].…”