Thiamine synthesis regulates the fermentation mechanisms in the fungus Aspergillus nidulans
Thiamine synthesis regulates the fermentation mechanisms in the fungus Aspergillus nidulans
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DOI：
10.1080/09168451.2016.1158631
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发表时间：
2016-09-01
影响因子：
1.6
通讯作者：
Takaya, Naoki
中科院分区：
文献类型：
--
作者：
Shimizu, Motoyuki;Masuo, Shunsuke;Takaya, Naoki
焦磷酸硫胺素（TPP）是一种重要的辅因子，其生物合成受TPP可用性的控制。在这里，我们破坏了预测的thiA基因的真菌构巢曲霉，并证明它是必不可少的合成细胞硫胺素。硫胺素核糖开关是TPP抑制基因表达的转录后机制，位于A. nidulans thiA前信使RNA。thiA核糖开关在硫胺素限制条件下没有完全去阻遏，在环境应激下完全去阻遏。在暴露于缺氧应激时，真菌积累了更多的ThiA和NmtA蛋白，以及比有氧条件下更多的硫胺素。thiA基因是真菌上调低氧支链氨基酸和乙醇发酵所需的，涉及含有TPP的酶。这些发现表明，缺氧通过硫胺素核糖开关调节thiA表达，并通过调节TPP酶的活性改变细胞发酵机制。
Thiamine pyrophosphate (TPP) is a critical cofactor and its biosynthesis is under the control of TPP availability. Here we disrupted a predicted thiA gene of the fungus Aspergillus nidulans and demonstrated that it is essential for synthesizing cellular thiamine. The thiamine riboswitch is a post-transcriptional mechanism for TPP to repress gene expression and it is located on A. nidulans thiA pre-messenger RNA. The thiA riboswitch was not fully derepressed under thiamine-limited conditions, and fully derepressed under environmental stressors. Upon exposure to hypoxic stress, the fungus accumulated more ThiA and NmtA proteins, and more thiamine than under aerobic conditions. The thiA gene was required for the fungus to upregulate hypoxic branched-chain amino acids and ethanol fermentation that involve enzymes containing TPP. These findings indicate that hypoxia modulates thiA expression through the thiamine riboswitch, and alters cellular fermentation mechanisms by regulating the activity of the TPP enzymes.