An Aspergillus nidulans uvsC null mutant is deficient in homologous DNA integration

ABSTRACT The pH of the environment has been implicated in controlling the yeast-hypha transition and pathogenesis of Candida albicans. Several C. albicans genes, includingPHR1 and PHR2, are pH dependent in their expression. To investigate the mechanism of pH-dependent expression, we have cloned and characterized PRR1 (for pH response regulator). PRR1 is homologous to palF, a component of the pH response pathway in Aspergillus nidulans. Expression of PRR1 was itself pH dependent, being maximal at acid pH but reduced severalfold at alkaline pH. In aprr1 null mutant the alkaline-induced expression ofPHR1 was completely abolished. Conversely, expression ofPHR2 was no longer repressed at alkaline pH. Aprr1 null mutant exhibited no morphological abnormalities at either pH; however, it lost the ability to form hyphae on medium 199 and on 10% serum plates. The ability to filament on serum was not restored by forced expression of PHR1, indicating that additional PRR1-dependent genes are required for hyphal development. These developmental genes appear to be distinct from those controlled by the developmental regulator EFG1, since theEFG1-dependent gene HWP1 was expressed normally in the prr1 null mutant. We conclude that PRR1encodes a component of the pH-dependent response pathway in C. albicans and that this pathway regulates the expression of multiple components of hyphal development.

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

F1000Research ◽

10.12688/f1000research.2-72.v1 ◽

2013 ◽

Vol 2 ◽

pp. 72 ◽

Cited By ~ 20

Author(s):

Margaret E Katz ◽

Kathryn Braunberger ◽

Gauncai Yi ◽

Sarah Cooper ◽

Heather M Nonhebel ◽

...

Keyword(s):

Aspergillus Nidulans ◽

Transcriptional Profiling ◽

Nutrient Stress ◽

Nutrient Sensing ◽

Carbon Limitation ◽

Nutrient Depletion ◽

Null Mutant ◽

Global Regulator ◽

Extracellular Proteases ◽

Number Of Genes

TheAspergillus nidulans xprGgene 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 anxprGΔnull mutant. Many of these genes are known to be regulated in response to carbon starvation. We confirmed that sterigmatocystin and penicillin production is reduced inxprG-mutants. The loss of fungal mass and secretion of pigments that accompanies fungal autolysis in response to nutrient depletion was accelerated in anxprG1gain-of-function mutant and decreased or absent in anxprG-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 inA. nidulans.

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