3.5. Transcriptional changes in central metabolic pathways
induced by gcr2
To better understand the effect of gcr2 on xylose metabolism, the
fold changes of DE genes in the glycolytic pathway, the PPP, and the
citric acid cycle were systematically compared between glucose and
xylose conditions (Fig. 4). Two significant transcriptional changes were
observed on both glucose and xylose conditions. First, gcr2 led
to the down-regulation of some glycolytic genes, most critically theGPM1 gene, encoding phosphoglycerate mutase, which is a key
enzyme of the lower glycolic pathway. Second, gcr2 up-regulated
non-oxidative PPP genes, most critically the TAL1 gene, encoding
transaldolase. However, in greater detail, gcr2 -mediated
transcriptional changes in central metabolic pathways were more
prominent during xylose metabolism. In addition to GPM1 gene,TDH2 , ENO1 , and CDC19 genes in the lower glycolytic
pathway were significantly down-regulated only under xylose conditions.
Moreover, SOL4 , GND2 , and TKL2 genes in oxidative
and non-oxidative PPP were up-regulated considerably only under xylose
conditions.