Fengzhu Ling1,2, Xin Tang3,4, Hao Zhang1,2,5,6, Yong Q Chen1,2,5,6, Jianxin Zhao1,2, Haiqin Chen1,2, Wei Chen1,2,5,7. 1. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, People's Republic of China. 2. School of Food Science and Technology, Jiangnan University, Wuxi, 214122, Jiangsu, People's Republic of China. 3. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, People's Republic of China. xintang@jiangnan.edu.cn. 4. School of Food Science and Technology, Jiangnan University, Wuxi, 214122, Jiangsu, People's Republic of China. xintang@jiangnan.edu.cn. 5. National Engineering Research Center for Functional Food, Jiangnan University, Wuxi, 214122, Jiangsu, People's Republic of China. 6. Wuxi Translational Medicine Research Center and Jiangsu Translational Medicine Research Institute Wuxi Branch, Wuxi, Jiangsu, 214122, People's Republic of China. 7. Beijing Innovation Centre of Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing, 100048, People's Republic of China.
Abstract
OBJECTIVES: The transport of citrate from the mitochondria to the cytoplasm is essential during lipid accumulation. This study aimed to explore the role of mitochondrial citrate-oxoglutarate carrier in lipid accumulation in the oleaginous fungus Mortierella alpina. RESULTS: Homologous MaYHM (the gene encoding the mitochondrial citrate-oxoglutarate carrier) was overexpressed in M. alpina. The fatty acid content of MaYHM-overexpressing recombinant strains was increased by up to 30% compared with the control. Moreover, the intracellular α-ketoglutarate level in recombinant strains was increased by 2.2 fold, together with a 23-35% decrease in NAD+-isocitrate dehydrogenase activity compared with the control. The overexpression of MaYHM altered the metabolic flux in the glutamate dehydrogenase shunt and 4-aminobutyric acid shunt during metabolic reprogramming, supplying more carbon to synthesize fatty acids. CONCLUSIONS: Overexpression of MaYHM resulted in more efflux of citrate from mitochondria to the cytoplasm and enhanced lipid accumulation. These findings provide new perspectives for the improvement of industrial lipid production in M. alpina.
OBJECTIVES: The transport of citrate from the mitochondria to the cytoplasm is essential during lipid accumulation. This study aimed to explore the role of mitochondrial citrate-oxoglutarate carrier in lipid accumulation in the oleaginous fungus Mortierella alpina. RESULTS: Homologous MaYHM (the gene encoding the mitochondrial citrate-oxoglutarate carrier) was overexpressed in M. alpina. The fatty acid content of MaYHM-overexpressing recombinant strains was increased by up to 30% compared with the control. Moreover, the intracellular α-ketoglutarate level in recombinant strains was increased by 2.2 fold, together with a 23-35% decrease in NAD+-isocitrate dehydrogenase activity compared with the control. The overexpression of MaYHM altered the metabolic flux in the glutamate dehydrogenase shunt and 4-aminobutyric acid shunt during metabolic reprogramming, supplying more carbon to synthesize fatty acids. CONCLUSIONS: Overexpression of MaYHM resulted in more efflux of citrate from mitochondria to the cytoplasm and enhanced lipid accumulation. These findings provide new perspectives for the improvement of industrial lipid production in M. alpina.
Authors: Amit Ghosh; David Ando; Jennifer Gin; Weerawat Runguphan; Charles Denby; George Wang; Edward E K Baidoo; Chris Shymansky; Jay D Keasling; Héctor García Martín Journal: Front Bioeng Biotechnol Date: 2016-10-05