Hongchao Wang1, Chen Zhang1, Haiqin Chen1, Qin Yang1, Xin Zhou1, Zhennan Gu1, Hao Zhang1, Wei Chen1, Yong Q Chen2,3. 1. State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122, Jiangsu, People's Republic of China. 2. State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122, Jiangsu, People's Republic of China. yqchen@jiangnan.edu.cn. 3. Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA. yqchen@jiangnan.edu.cn.
Abstract
OBJECTIVE: To clarify the molecular mechanism of GDP-L-fucose biosynthesis in Mortierella alpina. RESULTS: Analysis of the M. alpina genome suggests that there were two isofunctional GDP-D-mannose-4,6-dehydratase genes (GMD1 and GMD2) that have never been found in a microorganism before. GMD2 was expressed heterologously in Escherichia coli and purified to homogeneity. The addition of exogenous NAD(+) or NADP(+) was not essential for GMD2 activity. GMD2 may have considerable importance for GDP-L-fucose biosynthesis under nitrogen starvation. The transcriptional regulation of GMD1 may be more susceptible to GDP and GTP than that of GMD2. Significant changes were observed in the concentration of GDP-L-fucose (30 and 36 % inhibition respectively) and total fatty acids (18 and 12 % inhibition respectively) in M. alpina grown on GMD inhibitors medium, which suggests that GDP-L-fucose is functionally significant in lipid metabolism. CONCLUSIONS: This is the first time that an isofunctional GDP-D-mannose-4,6-dehydratase has been characterized in a microorganism.
OBJECTIVE: To clarify the molecular mechanism of GDP-L-fucose biosynthesis in Mortierella alpina. RESULTS: Analysis of the M. alpina genome suggests that there were two isofunctional GDP-D-mannose-4,6-dehydratase genes (GMD1 and GMD2) that have never been found in a microorganism before. GMD2 was expressed heterologously in Escherichia coli and purified to homogeneity. The addition of exogenous NAD(+) or NADP(+) was not essential for GMD2 activity. GMD2 may have considerable importance for GDP-L-fucose biosynthesis under nitrogen starvation. The transcriptional regulation of GMD1 may be more susceptible to GDP and GTP than that of GMD2. Significant changes were observed in the concentration of GDP-L-fucose (30 and 36 % inhibition respectively) and total fatty acids (18 and 12 % inhibition respectively) in M. alpina grown on GMD inhibitors medium, which suggests that GDP-L-fucose is functionally significant in lipid metabolism. CONCLUSIONS: This is the first time that an isofunctional GDP-D-mannose-4,6-dehydratase has been characterized in a microorganism.
Entities:
Keywords:
Characterization; De novo pathway; GDP-D-mannose-4,6-dehydratase; GDP-L-fucose; Isoform; Mortierella alpina