Systems metabolic engineering of Escherichia coli for L-threonine production.
Amino-acid producers have traditionally been developed by repeated random mutagenesis owing to the difficulty in rationally engineering the complex and highly regulated metabolic network. Here, we report the development of the genetically defined L-threonine overproducing Escherichia coli strain by systems metabolic engineering. Feedback inhibitions of aspartokinase I and III (encoded by thrA and lysC, respectively) and transcriptional attenuation regulations (located in thrL) were removed. Pathways for Thr degradation were removed by deleting tdh and mutating ilvA. The metA and lysA genes were deleted to make more precursors available for Thr biosynthesis. Further target genes to be engineered were identified by transcriptome profiling combined with in silico flux response analysis, and their expression levels were manipulated accordingly. The final engineered E. coli strain was able to produce Thr with a high yield of 0.393 g per gram of glucose, and 82.4 g/l Thr by fed-batch culture. The systems metabolic engineering strategy reported here may be broadly employed for developing genetically defined organisms for the efficient production of various bioproducts.
Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering (BK21 program), BioProcess Engineering Research Center, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.
Kwang Ho
KH
Lee
Jin Hwan
JH
Park
Tae Yong
TY
Kim
Hyun Uk
HU
Kim
Sang Yup
SY
Lee
D001692:Biological Transport; D049109:Cell Proliferation; D019295:Computational Biology; D004926:Escherichia coli / Q000166:cytology / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D005818:Genetic Engineering / Q000379:methods*; D006038:Glyoxylates / Q000378:metabolism; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism; D049490:Systems Biology / Q000379:methods*; D013912:Threonine / Q000096:biosynthesis*; D013997:Time Factors; D014158:Transcription, Genetic
D006038:Glyoxylates; D013912:Threonine; D010730:Phosphoenolpyruvate Carboxylase; C031150:glyoxylic acid