Lysine is widely used in food, medical and feed industries. The biosynthesis of L-lysine is closely related to NADPH level, but the regulation mechanism between the biosynthesis of L-lysine in C. glutamicum and the cofactor NADPH is still not clear. Here, a high intracellular NADPH level strain C. glutamicum XQ-5Δpgi::(zwf-gnd) was constructed by blocking the glycolytic pathway and overexpressing the pentose phosphate pathway in the lysine-producing strain C. glutamicum XQ-5, and the intracellular NADPH level in strain XQ-5Δpgi::(zwf-gnd) was increased from 3.57 × 10-5 nmol/(104 cells) to 1.8 × 10-4 nmol/(104 cell). Transcriptome analyses pointed to Cgl2680 as an important regulator of NADPH levels and L-lysine biosynthesis in C. glutamicum. By knocking out the gene Cgl2680, the intracellular NADPH level of the recombinant C. glutamicum lysCfbr ΔCgl2680 was raised from 7.95 × 10-5 nmol/(104 cells) to 2.04 × 10-4 nmol/(104 cells), consequently leading to a 2.3-fold increase in the NADPH/NADP+ ratio. These results indicated that the regulator Cgl2680 showed the negative regulation for NADPH regeneration. In addition, Cgl2680-deficient strain C. glutamicum lysCfbr ΔCgl2680 showed the increase of yield of both L-lysine and L-leucine as well as the increase of H2O2 tolerance. Collectively, our data demonstrated that Cgl2680 plays an important role in negatively regulating NADPH regeneration, and these results provides new insights for breeding L-lysine or L-leucine high-yielding strain.

中文翻译：

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破译 AraC 型转录调节因子 Cgl2680 对谷氨酸棒杆菌 NADPH 代谢和 l-赖氨酸生产的关键作用

赖氨酸广泛应用于食品、医药和饲料行业。L-赖氨酸的生物合成与NADPH水平密切相关，但谷氨酸棒杆菌中L-赖氨酸的生物合成与辅因子NADPH之间的调控机制尚不清楚。在这里，高细胞内 NADPH 水平菌株 C. glutamicum XQ-5Δpgi::(zwf-gnd) 是通过在产赖氨酸菌株 C. glutamicum XQ-5 中阻断糖酵解途径和过表达戊糖磷酸途径构建的，并且细胞内菌株 XQ-5Δpgi::(zwf-gnd) 中的 NADPH 水平从 3.57 × 10-5 nmol/（104 个细胞）增加到 1.8 × 10-4 nmol/（104 个细胞）。转录组分析指出 Cgl2680 是谷氨酸棒杆菌中 NADPH 水平和 L-赖氨酸生物合成的重要调节剂。通过敲除基因 Cgl2680，重组 C. 谷氨酸 lysCfbr ΔCgl2680 从 7.95 × 10-5 nmol/（104 个细胞）提高到 2.04 × 10-4 nmol/（104 个细胞），因此导致 NADPH/NADP+ 比率增加 2.3 倍。这些结果表明调节剂 Cgl2680 显示出对 NADPH 再生的负调节。此外，Cgl2680 缺陷菌株谷氨酸棒杆菌 lysCfbr ΔCgl2680 显示出 L-赖氨酸和 L-亮氨酸产量的增加以及 H2O2 耐受性的增加。总的来说，我们的数据表明 Cgl2680 在负调节 NADPH 再生中起着重要作用，这些结果为培育 L-赖氨酸或 L-亮氨酸高产菌株提供了新的见解。这些结果表明调节剂 Cgl2680 显示出对 NADPH 再生的负调节。此外，Cgl2680 缺陷菌株谷氨酸棒杆菌 lysCfbr ΔCgl2680 显示出 L-赖氨酸和 L-亮氨酸产量的增加以及 H2O2 耐受性的增加。总的来说，我们的数据表明 Cgl2680 在负调节 NADPH 再生中起着重要作用，这些结果为培育 L-赖氨酸或 L-亮氨酸高产菌株提供了新的见解。这些结果表明调节剂 Cgl2680 显示出对 NADPH 再生的负调节。此外，Cgl2680 缺陷菌株谷氨酸棒杆菌 lysCfbr ΔCgl2680 显示出 L-赖氨酸和 L-亮氨酸产量的增加以及 H2O2 耐受性的增加。总的来说，我们的数据表明 Cgl2680 在负调节 NADPH 再生中起着重要作用，这些结果为培育 L-赖氨酸或 L-亮氨酸高产菌株提供了新的见解。