The 2‐oxoglutarate supply exerts significant control on the lysine synthesis flux in Saccharomyces cerevisiae

Abstract

To determine the extent to which the supply of the precursor 2-oxoglutarate (2-OG) controls the synthesis of lysine in Saccharomyces cerevisiae growing exponentially in high glucose, top-down elasticity analysis was used. Three groups of reactions linked by 2-OG were defined. The 2-OG supply group comprised all metabolic steps leading to its formation, and the two 2-OG consumer groups comprised the enzymes and transporters involved in 2-OG transformation into lysine and glutamate and their further utilization for protein synthesis and storage. Various 2-OG steadystate concentrations that produced different fluxes to lysine and glutamate were attained using yeast mutants with increasing activities of Krebs cycle enzymes and decreased activities of Lys synthesis enzymes. The elasticity coefficients of the three enzyme groups were determined from the dependence of the amino acid fluxes on the 2-OG concentration. The respective degrees of control on the flux towards lysine (flux control coefficients) were determined from their elasticities, and were 1.1, 0.41 and À0.52 for the 2-OG producer group and the Lys and Glu branches, respectively. Thus, the predominant control exerted by the 2-OG supply on the rate of lysine synthesis suggests that over-expression of 2-OG producer enzymes may be a highly effective strategy to enhance Lys production.

Diversification of the kinetic properties of yeast NADP‐glutamate‐dehydrogenase isozymes proceeds independently of their evolutionary origin

“…It is possible that unknown activators contribute to modulation of the K. lactis enzyme in vivo. Interestingly, the S. cerevisiae and L. kluyveri enzymes are highly responsive to changes in α‐KG at the physiological concentrations (Table and Figure ) this suggests that the rate of glutamate synthesis is highly influenced by α‐KG availability as was previously proposed (Quezada et al., ). Worth of mention is the fact that there is growing evidence indicating that α‐KG plays a role in metabolic regulation.…”

Label-Free Proteomic Analysis of Flavohemoglobin Deleted Strain ofSaccharomyces cerevisiae

“…In the present study, downregulation of aconitase (Aco1p) which is also a Fe-S cluster containing protein and 2-oxoglutarate dehydrogenase (Kgd1) was observed in ΔYHB1 strain of S. cerevisiae . The supply of 2-oxoglutarate exerts significant control on the lysine synthesis flux in S. cerevisiae [ 45 ]. Thus, substrate unavailability due to downregulation of TCA cycle may result in the downregulation of lysine biosynthesis as observed in ΔYHB1 strain of S. cerevisiae .…”

13C NMR based profiling unveils different α-ketoglutarate pools involved into glutamate and lysine synthesis in the milk yeast Kluyveromyces lactis

“…Notably, the K. lactis Lys20 counterpart is devoided of this sequence, being shorter than the S. cerevisiae one (393 aa vs. 428 aa). Since the S. cerevisiae ortholog Lys20 has the mayor control on Lys biosynthetic flux, as compared to Lys21 [41], we can suggest that this control in K. lactis reside in the ER. The…”