Aspergillus nidulans AreA modulates its own transcriptional activity through controlling degradation of its co-repressor NmrA by a protease of insect origin.

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	Aspergillus nidulans AreA modulates its own transcriptional activity through controlling degradation of its co-repressor NmrA by a protease of insect origin.
	Li, A.; Parsania, C.; Todd, R.B; Tan, K.; Wong, K. H.
	2017-08-22
Source Publication	XII International Fungal Biology Conference
Abstract	In Aspergillus nidulans, nitrogen metabolism is tightly controlled by a conserved mechanism called Nitrogen Metabolite Repression (NMR). NMR is relieved by the global transcription factor AreA, which controls expression of hundreds of nitrogen utilization genes according to the nitrogen status of the cell. Under nitrogen sufficient conditions, AreA transcriptional activation is minimal because AreA is present at low levels and negatively controlled by its co-repressor NmrA, which is present at high levels. Upon nitrogen starvation, AreA transcriptional activation increases due to AreA nuclear accumulation and a simultaneous decrease in NmrA levels. Therefore, the inverse regulation of AreA and NmrA levels is critical for NMR. While the regulation of AreA activity has been well studied, relatively little is known for how NmrA levels are controlled. A previous study showed that NmrA can be degraded by a protease encoded by AN2366 in vitro (Zhao et al., 2010 Protein Sci. 19:1405). In this work, we have deleted AN2366 and confirmed that the AN2366 protease indeed negatively affects NmrA levels in vivo. Moreover, we found that AN2366 expression is controlled according to nitrogen conditions by AreA. We further show that the turnover of NmrA upon nitrogen starvation is significantly slowed down in both areA∆ and AN2366∆ strains, indicating that AreA positively stimulates AN2366 protease expression in order to rapidly degrade NmrA when cells are nitrogen-starved. Interestingly, this AN2366-mediated NmrA degradation does not seem to be conserved because AN2366 orthologue can only be found in just four filamentous fungi. In contrast, we noted many insect genomes carrying a trypsin-like protein with high sequence similarity to AN2366, suggesting that AN2366 was acquired via horizontal gene transfer from an insect. Taken together, our results reveal a previously unknown positive regulatory loop of AreA for its own transcriptional activity through controlling expression of a protease of insect origin.
Keyword	AreA NmrA Aspergillus nidulans
Language	英語English
The Source to Article	PB_Publication
PUB ID	32156
Document Type	Conference paper
Collection	DEPARTMENT OF BIOMEDICAL SCIENCES Faculty of Health Sciences
Corresponding Author	Wong, K. H.
Recommended Citation GB/T 7714	Li, A.,Parsania, C.,Todd, R.B,et al. Aspergillus nidulans AreA modulates its own transcriptional activity through controlling degradation of its co-repressor NmrA by a protease of insect origin.[C], 2017.
APA	Li, A.., Parsania, C.., Todd, R.B., Tan, K.., & Wong, K. H. (2017). Aspergillus nidulans AreA modulates its own transcriptional activity through controlling degradation of its co-repressor NmrA by a protease of insect origin.. XII International Fungal Biology Conference.

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