Shi Feng, Li Kun, Li Yongfu
State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China,
Biotechnol Lett. 2015 May;37(5):1063-71. doi: 10.1007/s10529-015-1768-6. Epub 2015 Feb 4.
Corynebacterium glutamicum ssp. lactofermentum strain JHI3-156 produces L-isoleucine (Ile). Overexpression of the Saccharomyces cerevisiae-derived NADH kinase gene (POS5) and the endogenous glucose-6-phosphate dehydrogenase and NAD kinase genes (zwf-ppnK) in JHI3-156 increased Ile production by 26 and 31 %, respectively. To decipher the global effect of POS5 and zwf-ppnK overexpression on Ile biosynthesis, proteomic analysis was conducted. Twenty-four differentially expressed proteins were identified in the POS5-overexpressing strain, most of which are related to inositol catabolism, central carbon metabolism, anaplerotic pathway, protein biosynthesis and the stress response. In the zwf-ppnK-overexpressing strain, seven differentially-expressed proteins, including PpnK and anaplerotic enzymes, were identified. This result indicates the involvement of a novel inositol catabolism step and the importance of the anaplerotic pathway in Ile biosynthesis. This finding will be helpful in the systematic metabolic engineering of C. glutamicum for Ile biosynthesis.
谷氨酸棒杆菌乳发酵亚种JHI3-156能够产生L-异亮氨酸（Ile）。在JHI3-156中过表达源自酿酒酵母的NADH激酶基因（POS5）以及内源性葡萄糖-6-磷酸脱氢酶和NAD激酶基因（zwf-ppnK），分别使Ile产量提高了26%和31%。为了解析POS5和zwf-ppnK过表达对Ile生物合成的全局影响，进行了蛋白质组学分析。在过表达POS5的菌株中鉴定出24种差异表达蛋白，其中大多数与肌醇分解代谢、中心碳代谢、回补途径、蛋白质生物合成以及应激反应有关。在过表达zwf-ppnK的菌株中，鉴定出7种差异表达蛋白，包括PpnK和回补酶。这一结果表明了一个新的肌醇分解代谢步骤的参与以及回补途径在Ile生物合成中的重要性。这一发现将有助于谷氨酸棒杆菌用于Ile生物合成的系统代谢工程。
