Nobel regulatory mechanism for transcription of genes encoding ribosomal components in S. cerevisiae

本研究对HMGB家族蛋白Hmo1在酿酒酵母中的功能进行了研究。Hmo1与分别由Pol I和Pol II转录的35S核糖体RNA基因和核糖体蛋白基因启动子结合，并根据环境条件协同调节这些基因的转录。通过对各种Hmo1突变菌株和蛋白质的分析，我们阐明了Hmo1通过功能未知的box A二聚化(或多聚化)，并以这种形式与靶DNA结合。此外，根据观察到酿酒酵母中HMO1基因的缺失和编码PPIase之一的FPR1基因的缺失导致了严重的生长缺陷，我们进行了遗传分析，以阐明该双干扰物生长缺陷的原因。因此，我们揭示了这些蛋白质在Pol I转录rRNA的起始阶段协同工作。

In this study, we conducted a research for the function of Hmo1 protein, a member of HMGB family proteins in S. cerevisiae. Hmo1 binds to the 35S ribosomal RNA gene and ribosomal protein gene promoters, which are transcribed by Pol I and Pol II, respectively, and regulates transcription of these genes cooperatively in response to environmental conditions. From analyses using various HMO1 mutant strains and proteins, we elucidated that Hmo1 dimerizes (or multimerizes) through box A, of which function has been unknown, and binds to target DNA in this form. In addition, based on the observation that deletion of HMO1 gene, in combination with deletion of FPR1 gene that encodes one of PPIase (peptidylprolyl isomerase) in S. cerevisiae, causes severe growth defect, we conducted genetic analyses to clarify the cause of a growth defect of this double disruptant. As the result, we revealed that these proteins work cooperatively at the step of initiation in transcription of rRNA by Pol I.