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Regulation of glutamine synthetase activity by transcriptional and posttranslational modifications negatively influences ganoderic acid biosynthesis in Ganoderma lucidum
Environmental Microbiology ( IF 5.1 ) Pub Date : 2021-01-12 , DOI: 10.1111/1462-2920.15400
Jing Zhu 1 , Shuqi Song 1 , Zehua Sun 1 , Lingdan Lian 1 , Liang Shi 1 , Ang Ren 1 , Mingwen Zhao 1
Affiliation  

Glutamine synthetase (GS), a central nitrogen metabolic enzyme, plays important roles in the nitrogen regulation network and secondary metabolism in fungi. However, the mechanisms by which external nitrogen sources regulate fungal GS activity have not been determined. Here, we found that GS activity was inhibited under nitrate conditions in Ganoderma lucidum. By constructing gs‐silenced strains and adding 1 mM GS inhibitor to inhibit GS activity, we found that a decrease in GS activity led to a decrease in ganoderic acid biosynthesis. The transcription of gs increased approximately five fold under nitrate conditions compared with that under ammonia. Electrophoretic mobility shift and yeast one‐hybrid assay showed that gs was transcriptionally regulated by AreA. Although both gs expression and GS protein content increased under nitrate conditions, the GS activity still decreased. Treatment of recombinant GS with SIN‐1 (protein nitration donor) resulted in a strengthened nitration accompanied by a 71% decrease in recombinant GS activity. Furthermore, intracellular GS could be nitrated from mycelia cultivated under nitrate conditions. These results indicated that GS activity could be inhibited by NO‐mediated protein nitration. Our findings provide the first insight into the role of transcriptional and posttranslational regulation of GS activity in regulating secondary metabolism in fungi.

中文翻译:

转录和翻译后修饰对谷氨酰胺合成酶活性的调节对灵芝灵芝酸生物合成产生负面影响

谷氨酰胺合成酶(GS)是一种中央的氮代谢酶,在真菌的氮调节网络和次级代谢中起着重要作用。但是,尚未确定外部氮源调节真菌GS活性的机制。在这里,我们发现灵芝中的硝酸盐条件下GS活性受到抑制。通过构建gs沉默的菌株并添加1 mM GS抑制剂来抑制GS活性,我们发现GS活性降低导致灵芝酸生物合成降低。与在氨水下相比,在硝酸盐条件下gs的转录增加了大约五倍。电泳迁移率变动和酵母单杂交检测表明GS由AreA转录调控。尽管在硝酸盐条件下gs表达和GS蛋白含量均增加,但GS活性仍下降。用SIN-1(蛋白质硝化供体)处理重组GS会导致硝化作用增强,同时重组GS活性降低71%。此外,可以从在硝酸盐条件下培养的菌丝体中硝化细胞内GS。这些结果表明,NO介导的蛋白质硝化可抑制GS的活性。我们的发现为GS活性的转录和翻译后调节在调节真菌的次级代谢中的作用提供了第一个见识。
更新日期:2021-02-24
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