3.3. Global transcriptional changes induced by gcr2
GCR2 encodes a transcriptional activator of glycolytic genes; therefore, its deletion leads to the transcriptional down-regulation of glycolytic genes and up-regulation of citric acid cycle genes during glucose metabolism (Fendt et al., 2010; Sasaki and Uemura, 2005; Uemura and Jigami, 1992). To investigate the transcriptional changes by gcr2 during xylose metabolism,S. cerevisiae SR7 and SR7 gcr2 strains grown on glucose or xylose were subjected to RNA-seq, and high-quality sequencing data were obtained (Table 2). Hierarchical clustering and multivariate analysis based on Pearson’s correlation and principal component analysis, respectively, indicated that the transcriptomic profiles of glucose and xylose metabolism were the primary determinants (Fig. 2). Notably,gcr2 mutant samples were clustered separately from control samples on both glucose and xylose fermentation conditions, suggesting global transcriptional changes evoked by gcr2 regardless of the type of substrate. Meanwhile, the number of DE genes in the gcr2mutant compared to the control strain (p < 0.05, >2-fold) was 1638 and 605 on glucose and xylose, respectively. Also, the most significant DE genes in the gcr2mutant compared to the control strain (p < 0.01, >10-fold) were 17 and 5 on glucose and xylose, respectively (Table 3). The larger number of DE genes and the more significant fold changes under glucose conditions suggest that Gcr2 is responsible for more global transcriptional regulation of glucose metabolism compared to xylose metabolism.