光滑球拟酵母中α-酮戊二酸脱氢酶系生理作用

Physiological function of α-ketoglutarate dehydrogenase complex in Torulopsis glabrata

摘要:

摘要：【目的】研究α-酮戊二酸脱氢酶系在光滑球拟酵母碳代谢流、能量代谢和氨基酸代谢中的生理作用。【方法】通过敲除光滑球拟酵母中编码α-酮戊二酸脱氢酶系中E1酶的基因kgd1，构建α-酮戊二酸脱氢酶活性缺失菌株T. glabrata kgd1::kan，并考察KGDH缺失引起TCA循环关键酶活性，碳代谢流量以及胞内氨基酸和能荷水平等方面的变化。【结果】光滑球拟酵母中α-酮戊二酸脱氢酶活性的缺失导致：(1)细胞启动乙醛酸途径，通过形成TCA-乙醛酸循环实现TCA循环的正常代谢；(2)胞内NADH/NAD+水平

Abstract:

Abstract: [Objective] We studied the physiological function of α-ketoglutarate dehydrogenase complex (KGDH) on the metabolism of Torulopsis glabrata. [Methods] With manipulation of KGDH in Torulopsis glabrata, we screened a mutant strain T. glabrata kgd1::kan, in which the kgd1 gene encoding the E1 subunit of KGDH was deleted. [Results] Disruption of KGDH resulted in: (a) the enhancement of glyoxalate pathway as a complementarity for carbon metabolism in TCA cycle; (b) compared with that of the control, the ratio of NADH/NAD+ and ATP/ADP decreased by 33.7% and 31.8%, respectively. But the specific activities of pyruvate dehydrogenase, isocitrate dehydrogenase and malate dehydrogenase increased by 58.1%, 33.3% and 32.5%, respectively; (c) the intracellular concentration of pyruvate was reduced by 49.9%, while the intracellular concentration of succinate, malate and α-ketoglutarate was higher 172.7%, 66.1% and 41.1% than the corresponding values of the control; (d) The content of pyruvate-family amino acid was 29.3% lower while the level of glutamate-family amino acid and aspartate-family amino acid were 34.7% and 26.8% higher than that of control. [Conclusions] Those results present here demonstrated that α-ketoglutarate dehydrogenase complex plays essential role on the metabolism of yeast.