FIG 2.

gdhA1 and the BcdhE1 gene in the bkd operon are involved in BCAA degradation. (A) Schematic of branched-chain amino acid (taking valine as an example) catabolic pathways in S. erythraea. GDH, glutamate dehydrogenase; BCDH, branched-chain α-keto acid dehydrogenase; AldH, aldehyde dehydrogenase; PCC, propionyl-CoA carboxylase. (B) Growth curves of S. erythraea WT, ΔgdhA1, and ΔgdhA1/pIB-gdhA1 strains cultivated in basic Evans medium with 30 mM valine and growth curves of ΔgdhA1 strain cultivated in basic Evans medium with 30 mM valine plus 170 mM α-ketoglutarate. (C) Growth curves of S. erythraea WT, ΔBcdhE1, and ΔBcdhE1/pIB-BcdhE1 strains cultivated in basic Evans medium with 30 mM valine and growth curves of the ΔBcdhE1 strain cultivated in basic Evans medium with 30 mM valine plus 140 mM glucose.