De novo biosynthesis of α-aminoadipate via multi-strategy metabolic
engineering in Escherichia coli
Abstract
As a non-protein amino acid, α-aminoadipate is used in the fields of
medicine, chemical engineering, and others. In addition, α-aminoadipate
is an important precursor for the synthesis of β-lactam antibiotics. In
this study, we construct a biosynthesis pathway of α-aminoadipate in
Escherichia coli using lysine as the precursor and produce
α-aminoadipate using a microbial cell factory for the first time. In
addition, we regulate the cell metabolism to improve the titer of
α-aminoadipate via multi-strategy metabolic engineering. First, a novel
synthetic pathway was constructed to realize the de novo synthesis of
α-aminoadipate with the titers of 82 mg/L. Second, the key enzymes
involved in enhancing precursor synthesis were overexpressed and the CO2
fixation process was introduced, and these led to 80% and 34%
increases in the α-aminoadipate concentration, reaching 147 mg/L and 110
mg/L, respectively. Third, cofactor regulation was used to maintain the
coupling balance of material and energy, with the intracellular
α-aminoadipate concentration reaching 140 mg/L. Fourth, the weakening of
the synthesis of acetic acid was used to strengthen the synthesis of
α-aminoadipate, and this resulted in the enhancement of the
α-aminoadipate concentration by 2.2 times, reaching 263 mg/L. Finally,
combination optimization was used to promote the production of
α-aminoadipate. The titers of α-aminoadipate reached 415 mg/L, which was
4 times higher than that of the parent strain. This study is the first
to present the effective biosynthesis of α-aminoadipate in E. coli.