Functional Analysis of the Nitrogen Metabolite Repression Regulator Gene nmrA in Aspergillus flavus

Abstract

In Aspergillus nidulans, the nitrogen metabolite repression (NMR) regulator NmrA plays a major role in regulating the activity of the GATA transcription factor AreA during nitrogen metabolism. However, the function of nmrA in A. flavus has not been previously studied. Here, we report the identification and functional analysis of nmrA in A. flavus. Our work showed that the amino acid sequences of NmrA are highly conserved among Aspergillus species and that A. flavus NmrA protein contains a canonical Rossmann fold motif. Deletion of nmrA slowed the growth of A. flavus but significantly increased conidiation and sclerotia production. Moreover, seed infection experiments indicated that nmrA is required for the invasive virulence of A. flavus. In addition, the ΔnmrA mutant showed increased sensitivity to rapamycin and methyl methanesulfonate, suggesting that nmrA could be responsive to target of rapamycin signaling and DNA damage. Furthermore, quantitative real-time reverse transcription polymerase chain reaction analysis suggested that nmrA might interact with other nitrogen regulatory and catabolic genes. Our study provides a better understanding of NMR and the nitrogen metabolism network in fungi.

Transcriptomic Insights into the Antifungal Effects of Magnolol on the Growth and Mycotoxin Production of Alternaria alternata

“…The growth and mycotoxin production in fungi is also influenced by the available carbon and nitrogen sources and the corresponding regulators [ 20 , 39 , 40 ]. The transcription factors CreA, AreA and NmrA play important roles in modulating the expression of genes for utilizing these nutrient sources [ 14 , 16 , 41 ].…”

“…In the nitrogen metabolic regulation, although there was no obvious significant difference in AreA expression, NmrA demonstrated lower levels of transcription in A. alternata with magnolol treatment. NmrA appears to affect gene expression through physical interaction with AreA [ 42 ], and also be involved in the mycotoxin biosynthesis and virulence of pathogens [ 18 , 40 ]. The NmrA deletion partially restricted the production of aflatoxin [ 40 ] and deoxynivalenol [ 43 ] in some minimal media with one amino acid as the sole nitrogen resource.…”

Antioxidant‐related catalase CTA1 regulates development, aflatoxin biosynthesis, and virulence in pathogenic fungus Aspergillus flavus

“…Aflatoxin B1 (AFB1) of all the mycotoxin holds the highest toxicity. It is widely distributed across agricultural products and acts as a potent carcinogen, mutagen and teratogen (Yang et al, 2015;Han et al, 2016;Xing et al, 2016). The protracted consumption of AFs in both humans and animals leads to immunosuppression, growth impairment and DNA damage (Khlangwiset et al, 2011;Zhang et al, 2015).…”

Gas Chromatography–Mass Spectrometry Profiling of Volatile Compounds Reveals Metabolic Changes in a Non-Aflatoxigenic Aspergillus flavus Induced by 5-Azacytidine

“…Here, we found that the NT mutant was a defect in aflatoxins biosynthesis. Former studies have demonstrated that specific nutrients, like vitamins, amino acids and fatty acids are necessary for AFs formation [30]. In the AF biosynthesis pathway, it starts from acetyl-CoA, which is synthesized via oxidative decarboxylation of pyruvate, β-oxidation of fatty acids, or from ketogenic amino acids in primary metabolism [31].…”