1. Construction and Application of PLP Self-sufficient Biocatalysis System for Threonine Aldolase.
- Author
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Zheng W, Chen K, Fang S, Cheng X, Xu G, Yang L, and Wu J
- Subjects
- Bacillus enzymology, Bacillus genetics, Bacillus subtilis enzymology, Bacillus subtilis genetics, Biocatalysis, Culture Media metabolism, Enzymes, Immobilized chemistry, Enzymes, Immobilized genetics, Epoxy Resins chemistry, Escherichia coli genetics, Escherichia coli metabolism, Glutaminase genetics, Glutaminase metabolism, Glycine Hydroxymethyltransferase chemistry, Glycine Hydroxymethyltransferase genetics, Half-Life, Polyethyleneimine chemistry, Pyridoxal Phosphate biosynthesis, Pyridoxal Phosphate chemistry, Enzymes, Immobilized metabolism, Glycine Hydroxymethyltransferase metabolism, Pyridoxal Phosphate metabolism
- Abstract
A number of organic synthesis involve threonine aldolase (TA), a pyridoxal phosphate (PLP)-dependent enzyme. Although the addition of exogenous PLP is necessary for the reactions, it increases the cost and complicates the purification of the product. This work constructed a PLP self-sufficient biocatalysis system for TA, which included an improvement of the intracellular PLP level and co-immobilization of TA with PLP. Engineered strain BL-ST was constructed by introducing PLP synthase PdxS/T to Escherichia coli BL21(ED3). The intracellular PLP concentration of the strain increased approximately fivefold to 48.5 μmol/g
DCW . l-TA, from Bacillus nealsonii (BnLTA), was co-expressed in the strain BL-ST with PdxS/T, resulting in the engineered strain BL-BnLTA-ST. Compared with the control strain BL-BnLTA (254.1 U/L), the enzyme activity of the strain BL-BnLTA-ST reached 1518.4 U/L without the addition of exogenous PLP. An efficient co-immobilization system was then designed. The epoxy resin LX-1000HFA wrapped by polyethyleneimine (PEI) acted as a carrier to immobilize the crude enzyme solution of the strain BL-BnLTA-ST mixed with an extra 100 μM of exogenous PLP, resulting in the catalyst HFAPEI -BnLTA-STPLP 100. HFAPEI -BnLTA-STPLP 100 exhibited a half-life of approximately 450 h, and the application of the catalyst in the continuous biosynthesis of 3-[4-(methylsulfonyl) phenyl] serine had more than 180 batch reactions (>60%conv ) without the extra addition of exogenous PLP. The excellent compatibility and stability of the system were further confirmed by other TAs. This work introduced a PLP self-sufficient biocatalysis system that can reduce the cost of PLP and contribute to the industrial application of TA. In addition, the system may also be applied in other PLP-dependent enzymes., (Copyright © 2020 Elsevier Inc. All rights reserved.)- Published
- 2020
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