PDF(Pubmed)
Abstract：
Thiamine (vitamin B1) is essential for glucose catabolism. In the yeast species, Nakaseomyces glabratus (formerly Candida glabrata) and Saccharomyces cerevisiae, the transcription factor Pdc2 (with Thi3 and Thi2) upregulates pyruvate decarboxylase (PDC) genes and thiamine biosynthetic and acquisition (THI) genes during starvation. There have not been genome-wide analyses of Pdc2 binding. Previously, we identified small regions of Pdc2-regulated genes sufficient to confer thiamine regulation. Here, we performed deletion analyses on these regions. We observed that when the S. cerevisiae PDC5 promoter is introduced into N. glabratus, it is thiamine starvation inducible but does not require the Thi3 coregulator. The ScPDC5 promoter contains a 22-bp duplication with an AT-rich spacer between the 2 repeats, which are important for regulation. Loss of the first 22-bp element does not eliminate regulation, but the promoter becomes Thi3 dependent, suggesting cis architecture can generate a Thi3-independent, thiamine starvation inducible response. Whereas many THI promoters only have 1 copy of this element, addition of the first 22-bp element to a Thi3-dependent promoter confers Thi3 independence. Finally, we performed fluorescence anisotropy and chromatin immunoprecipitation sequencing. Pdc2 and Thi3 bind to regions that share similarity to the 22-bp element in the ScPDC5 promoter and previously identified cis elements in N. glabratus promoters. Also, while Pdc2 binds to THI and PDC promoters, neither Pdc2 nor Thi3 appears to bind the evolutionarily new NgPMU3 promoter that is regulated by Pdc2. Further study is warranted because PMU3 is required for cells to acquire thiamine from environments where thiamine is phosphorylated, such as in the human bloodstream.
摘要：
硫胺素（维生素B1）对葡萄糖分解代谢至关重要。在酵母菌种Nakaseomycesglabratus（以前称为假丝酵母）和酿酒酵母中，转录因子Pdc2（具有Thi3和Thi2）在饥饿期间上调丙酮酸脱羧酶（PDC）基因和硫胺素生物合成和获得（THI）基因。尚未进行Pdc2结合的全基因组分析。以前,我们确定了足以赋予硫胺素调节的Pdc2调节基因的小区域。这里,我们对这些区域进行了缺失分析.我们观察到，当酿酒酵母PDC5启动子被引入光乳杆菌时，它是可诱导的硫胺素饥饿，但不需要Thi3共调节剂。ScPDC5启动子包含一个22bp的重复，两个重复之间有一个富含AT的间隔区，这对监管很重要。第一个22bp元件的损失并不能消除调节，但是启动子变得依赖于Thi3，暗示顺式架构可以产生独立的Thi3，硫胺素饥饿诱导反应。虽然许多THI发起人只有一个这个元素的副本，向Thi3依赖性启动子添加第一个22bp元件赋予Thi3独立性。最后,我们进行了荧光各向异性和ChIP-seq。Pdc2和Thi3结合到与ScPDC5启动子中的22bp元件具有相似性的区域，并且先前鉴定了N.glabratus启动子中的顺式元件。此外，而Pdc2与THI和PDC启动子结合，Pdc2和Thi3似乎都不结合受Pdc2调控的进化上新的NgPMU3启动子。进一步的研究是有必要的，因为PMU3是必需的细胞从环境中硫胺素磷酸化获得硫胺素，比如在人体血液中。
