Non-Histone Proteins and the Mediator Complex are Essential for the Transcription of HXT2 and HXT4 Genes in Saccharomyces cerevisiae

Transcriptional activation of HXT2 and HXT4 genes require rapid reorganization of the chromatin structure on the promoter regions of these genes. In this study, it was found that the transcription of HXT2 and HXT4 genes decreased 4- to 7-foldin the yeast strain that does not contain the non-histone proteins 6A and 6B (Nhp6A/B). In addition, results of this research indicatedthat Nhp6A/B are required for the rapid derepression and activation of HXT2 and HXT4 transcription upon glucose signaling.Furthermore, it was found that Med2p, which provides the connection between the transcriptional activators and the basaltranscription factors, is also required for the activation of HXT2 and HXT4 transcription. Transcription of HXT2 and HXT4 decreased2- to 13-fold in Med2 mutant S. cerevisiae cells. These results indicated that Nhp6A/B and the mediator complex are essential for the regulation of HXT2 and HXT4 gene transcription in S. cerevisiae.