Enzyme and Microbial Technology, Vol.87-88, 79-85, 2016
Overexpression of ppc and lysC to improve the production of 4-hydroxyisoleucine and its precursor L-isoleucine in recombinant Corynebacterium glutamicum ssp lactofermentum
4-hydroxyisoleucine (4-HIL) exhibits unique insulinotropic and insulin-sensitizing activities and is an attractive candidate for the treatment of type II and type I diabetes. In our previous study, L-isoleucine dioxygenase gene (ido) was cloned and overexpressed in an L-isoleucine-producing strain, Corynebacterium glutamicum ssp. lactofermentum SN01, and 4-HIL was produced from the endogenous L-isoleucine (Ile). In this study, ppc and lysC were co-expressed with ido to increase the supply of Ile, the direct precursor of 4-HIL, and to further improve the 4-HIL yield. After 144 h of fermentation, the ido-ppc-expressing strain produced 95.72 +/- 1.52 mM 4-HIL, 29% higher than the ido-expressing strain. The co-expression of lysC and ppc with ido resulted in a further 35% increment of carbon flux to L-aspartate family amino acids biosynthesis pathway. However, the conversion ratio of Ile to 4-HIL and the 4-HIL yield decreased to 0.31 mol/mol and 30.16 +/- 2.01 mM, respectively, likely due to the decreased IDO activity caused by lower pH and higher intracellular Ile concentration. Therefore, co-expression of ido and ppc was benefit for 4-HIL de novo biosynthesis, while co-expression of lysC with ido and ppc decreased the conversion ratio of Ile to 4-HIL. (C) 2016 Elsevier Inc. All rights reserved.