Fig. 4.

CodY prioritizes BCAA aminotransferase gene expression. (A) YbgE, YwaA, and Bcd mediate interconversion of α-keto acids (BCKAs) and their cognate amino acids (BCAAs). (B) CodY regulates the expression of bcd indirectly. Inactivation of CodY leads to increased synthesis of Ile and Val, both of which can activate BkdR, the positive regulator of bcd. (C) ywaA and bcd were substantially derepressed when CodY activity was mildly reduced, whereas ybgE was derepressed more than 50% only in the strain lacking CodY activity. (D) Heat map displays the relationship between strains with varying levels of CodY activity and the fate of pyruvate. Changes in the abundance of each metabolite (Dataset S6) are color-coded, with red and blue indicating an increase or decrease in intracellular abundance, respectively, relative to the baseline (abundance in the WT) on a log(2) scale. Strains and statistical testing are presented as described in the legend for Fig. 3.