期刊
MICROBIAL CELL FACTORIES
卷 18, 期 1, 页码 -出版社
BMC
DOI: 10.1186/s12934-019-1177-y
关键词
N-Acetylglutamate; Acetyl-CoA; Glucose; Acetate; Fatty acid
资金
- National Natural Science Foundation of China [31670051]
Background Acetyl-CoA is an important metabolic intermediate and serves as an acetylation precursor for the biosynthesis of various value-added acetyl-chemicals. Acetyl-CoA can be produced from glucose, acetate, or fatty acids via metabolic pathways in Escherichia coli. Although glucose is an efficient carbon source for acetyl-CoA production, the pathway from acetate to acetyl-CoA is the shortest and fatty acids can produce acetyl-CoA through fatty acid oxidation along with abundant NADH and FADH(2). In this study, metabolically engineered E. coli strains for efficiently supplying acetyl-CoA from glucose, acetate, and fatty acid were constructed and applied in one-step biosynthesis of N-acetylglutamate (NAG) from glutamate and acetyl-CoA. Results A metabolically engineered E. coli strain for NAG production was constructed by overexpressing N-acetylglutamate synthase from Kitasatospora setae in E. coli BW25113 with argB and argA knockout. The strain was further engineered to utilize glucose, acetate, and fatty acid to produce acetyl-CoA. When glucose was used as a carbon source, the combined mutants of increment ptsG::glk, increment galR::zglf, increment poxB::acs, increment ldhA, and increment pta were more efficient for supplying acetyl-CoA. The acetyl-CoA synthetase (ACS) pathway and acetate kinase-phosphate acetyltransferase (ACK-PTA) pathway from acetate to acetyl-CoA were investigated, and the ACK-PTA pathway showed to be more efficient for supplying acetyl-CoA. When fatty acid was used as a carbon source, acetyl-CoA supply was improved by deletion of fadR and constitutive expression of fadD under the strong promoter CPA1. Comparison of acetyl-CoA supply from glucose, acetate and palmitic acid revealed that a higher conversion rate of glutamate (98.2%) and productivity (an average of 6.25 mmol/L/h) were obtained when using glucose as a carbon source. The results also demonstrated the great potential of acetate and fatty acid to supply acetyl-CoA, as the molar conversion rate of glutamate was more than 80%. Conclusions Metabolically engineered E. coli strains were developed for NAG production. The metabolic pathways of acetyl-CoA from glucose, acetate, or fatty acid were optimized for efficient acetyl-CoA supply to enhance NAG production. The metabolic strategies for efficient acetyl-CoA supply used in this study can be exploited for other chemicals that use acetyl-CoA as a precursor or when acetylation is involved.
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