Effects of pyruvate dehydrogenase subunits overexpression on the α-ketoglutarate production in Yarrowia lipolytica WSH-Z06

Yarrowia lipolytica WSH-Z06 harbours a promising capability to oversynthesize alpha-ketoglutarate (alpha-KG). Its wide utilization is hampered by the formation of high concentrations of pyruvate. In this study, a metabolic strategy for the overexpression of the alpha and beta subunits of pyruvate dehydrogenase E1, E2 and E3 components was designed to reduce the accumulation of pyruvate. Elevated expression level of alpha subunit of E1 component improved the alpha-KG production and reduced the pyruvate accumulation. Due to a reduction in the acetyl-CoA supply, neither the growth of cells nor the synthesis of alpha-KG was restrained by the overexpression of beta subunit of E1, E2 and E3 components. Furthermore, via the overexpression of these thiamine pyrophosphate (TPP)-binding subunits, the dependency of pyruvate dehydrogenase on thiamine was diminished in strains T1 and T2, in which alpha and beta subunits of E1 component were separately overexpressed. In these two recombinant strains, the accumulation of pyruvate was insensitive to variations in exogenous thiamine. The results suggest that alpha-KG production can be enhanced by altering the dependence on TPP of pyruvate dehydrogenase and that the competition for the cofactor can be switched to ketoglutarate dehydrogenase via separate overexpression of the TPP-binding subunits of pyruvate dehydrogenase. The results presented here provided new clue to improve alpha-KG production.