期刊
FRONTIERS IN MICROBIOLOGY
卷 13, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fmicb.2022.1003709
关键词
Aspergillus nidulans; environmental stress; conidiospore; cleistothecium; sterigmatocystin
类别
资金
- European Union
- European Social Fund [EFOP-3.6.1-162016-00022]
- Laboratory for the Analysis and Application of Industry Big Data [TKP2021EGA-20]
- National Research, Development and Innovation Office [NKFIH K119494, NN125671]
- UW Food Research Institute
In this study, the two bZIP type TFs AtfA and AtfB were functionally characterized to play key roles in stress response pathways in filamentous fungi, with significant effects on oxidative stress sensitivity and heavy metal stress tolerance.
Transcription factors (TFs) with the basic leucin zipper domain are key elements of the stress response pathways in filamentous fungi. In this study, we functionally characterized the two bZIP type TFs AtfA and AtfB by deletion (Delta) and overexpression (OE) of their encoding genes in all combination: Delta atfA, Delta atfB, Delta atfA Delta atfB, Delta atfAatfBOE, Delta atfBatfAOE, atfAOE, atfBOE and atfAOEatfBOE in Aspergillus nidulans. Based on our previous studies, Delta atfA increased the sensitivity of the fungus to oxidative stress mediated by menadione sodium bisulfite (MSB) and tert-butylhydroperoxide (tBOOH), while Delta atfB was not sensitive to any oxidative stress generating agents, namely MSB, tBOOH and diamide at all. Contrarily, the Delta atfB mutant was sensitive to NaCl, but tolerant to sorbitol. Overexpression of atfB was able to compensate the MSB sensitivity of the Delta atfA mutant. Heavy metal stress elicited by CdCl2 reduced diameter of the atfBOE and atfAOEatfBOE mutant colonies to about 50% of control colony, while the cell wall stress generating agent CongoRed increased the tolerance of the Delta atfA mutant. When we tested the heat stress sensitivity of the asexual spores (conidiospores) of the mutants, we found that conidiospores of Delta atfAatfBOE and Delta atfBatfAOE showed nearly 100% tolerance to heat stress. Asexual development was negatively affected by Delta atfA, while atfAOE and atfAOE coupled with Delta atfB increased the number of conidiospores of the fungus approximately 150% compared to the control. Overexpression of atfB led to a 25% reduction in the number of conidiospores, but increased levels of abaA mRNA and size of conidiospores. Sexual fruiting body (cleistothecium) formation was diminished in the Delta atfA and the Delta atfA Delta atfB mutants, while relatively elevated in the Delta atfB and the Delta atfBatfAOE mutants. Production of the mycotoxin sterigmatocystin (ST) was decreased to undetectable levels in the Delta atfA mutant, yet ST production was restored in the Delta atfA Delta atfB mutant, suggesting that Delta atfB can suppress ST production defect caused by Delta atfA. Levels of ST were also significantly decreased in the Delta atfAatfBOE, Delta atfBatfAOE and atfAOEatfBOE mutants.
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