A p53-like transcription factor similar to Ndt80 controls the response to nutrient stress in the filamentous fungus, Aspergillus nidulans

Abstract

The Aspergillus nidulans xprG gene encodes a putative transcriptional activator that is a member of the Ndt80 family in the p53-like superfamily of proteins. Previous studies have shown that XprG controls the production of extracellular proteases in response to starvation. We undertook transcriptional profiling to investigate whether XprG has a wider role as a global regulator of the carbon nutrient stress response. Our microarray data showed that the expression of a large number of genes, including genes involved in secondary metabolism, development, high-affinity glucose uptake and autolysis, were altered in an xprG Δ null mutant. Many of these genes are known to be regulated in response to carbon starvation. We confirmed that sterigmatocystin and penicillin production is reduced in xprG - mutants. The loss of fungal mass and secretion of pigments that accompanies fungal autolysis in response to nutrient depletion was accelerated in an xprG1 gain-of-function mutant and decreased or absent in an xprG - mutant. The results support the hypothesis that XprG plays a major role in the response to carbon limitation and that nutrient sensing may represent one of the ancestral roles for the p53-like superfamily. Disruption of the AN6015 gene, which encodes a second Ndt80-like protein, showed that it is required for sexual reproduction in A. nidulans.

The N‐acetylglucosamine catabolic gene cluster in Trichoderma reesei is controlled by the Ndt80‐like transcription factor RON1

“…The increased induction levels of the structural GlcNAc catabolic genes in T. reesei in response to GlcNAc (Fig. 3) are substantially higher (> 100-fold) than for any gene mentioned by Katz et al (2013) in their genome-wide transcriptome analysis of carbon starvation in A. nidulans. Nevertheless, one of the best induction ratios comparing xprG + and xprG − strains (6-fold) was reported for hxkC.…”

“…While in S. cerevisiae Ndt80 is primarily involved in the regulation of meiosis, the Ndt80-like proteins in N. crassa (VIB-1, FSD-1) have other functions. Mutations in fsd-1 affected the timing and development of female reproductive structures and ascospore maturation (Hutchison and Glass, 2010), and the A. nidulans homolog, ndtA, is apparently required for sexual reproduction (Katz et al, 2013). Further, VIB-1 is involved in the regulation of vegetative incompatibility and programmed cell death.…”

Discovery of McrA, a master regulator of Aspergillus secondary metabolism

“…mcrA is a master transcription regulator mcrA regulates several SM BGCs and this implies that it is involved in the regulation of transcription of many genes involved in SM biosynthesis. Secondary metabolism is intimately connected to a number of other processes in the cell, however, such as primary metabolism and development Katz et al, 2013;de Souza et al, 2013;Brakhage, 2013;Garzia et al, 2013). We wished to determine, therefore, if the effects of mcrA on gene expression extended beyond genes involved in secondary metabolism.…”

VibA, a Homologue of a Transcription Factor for Fungal Heterokaryon Incompatibility, Is Involved in Antifungal Compound Production in the Plant-Symbiotic Fungus Epichloë festucae

“…Further supporting this deduction are the two E. festucae E437 nonantifungal mutants we isolated recently, T547 and T692, which show extracellular protease activity comparable to that of wild-type E437 (T. Hashikawa and D. Takemoto, unpublished data). Altogether, the data show that, given that NDT80/PhoG- type transcription factors of S. cerevisiae, C. albicans, and A. nidulans have large numbers of direct target genes (45,49,51), it is likely that the genes for the production of inhibitory metabolites in E. festucae, rather than the cell lytic enzymes, are critical targets of VibA for the antifungal activity of the endophyte.…”

“…Deletion mutants of xprG cannot utilize proteins as a carbon or nitrogen source (50). More recently, Katz et al (51) reported that XprG regulates a large number of genes in response to carbon starvation, including the genes required for the production of secondary metabolites, such as penicillin and sterigmatocystin. The E. festucae vibA mutant, like the N. crassa vib-1 and A. nidulans xprG mutants (39,50), is also defective in the production of extracellular protease.…”