Regulatory effects of cellular nicotinamide nucleotides and enzyme activities on poly(3-hydroxybutyrate) synthesis in recombinant Escherichia coli
Cited 0 time in
- Regulatory effects of cellular nicotinamide nucleotides and enzyme activities on poly(3-hydroxybutyrate) synthesis in recombinant Escherichia coli
- In Young Lee; Mi Kyung Kim; Young Hoon Park; Sang Yup Lee
- Bibliographic Citation
- Biotechnology and Bioengineering, vol. 52, pp. 707-712
- Publication Year
- Regulatory roles of nicotinamide nucleotides and three key enzymes, β- ketothiolase (KT), NADPH-dependent acetoacetyl-CoA reductase (AAR), and citrate synthase (CS), on poly(3-hydroxybutyrate) (PHB) synthesis in recombinant Escherichia coli harboring a plasmid containing the Alcaligenes eutrophus polyhydroxyalkanoate (PHA) biosynthesis genes were examined. Cells were grown in various media and were subsequently compared for PHB concentration, PHB content, the activities of the key enzymes, and the levels of nicotinamide nucleotides. Cells of recombinant E. coli accumulated the largest amount of PHB in LB+glucose medium among those tested. PHB synthesis was not enhanced by limiting inorganic ions. The activity of CS, which competes with KT for acetyl-CoA, was lower when cells were grown in LB+glucose compared with other media. The NADPH level and the NADPH/NADP ratio were high in LB+glucose. Examination of the time profiles of the specific PHB synthesis rate, key enzyme activities, and the levels of nicotinamide nucleotides showed that PHB synthesis is most significantly affected by the NADPH level. Even though the NADH level and the NADH/NAD ratio were also high during the synthesis of PHB, no direct evidence of their positive effect on PHB synthesis was found. Low activity of CS was beneficial for PHB synthesis due to the availability of more acetyl-CoA to PHB biosynthetic pathway. In recombinant E. coli, the level of NADPH and/or the NADPH/NADP ratio seem to be the most critical factor regulating the activity of AAR and, subsequently, PHB synthesis.
- poly(3-hydroxybutyrate)regulationescherichia colinicotinamide nucleotidesPHB synthesis
- Appears in Collections:
- 1. Journal Articles > Journal Articles
- Files in This Item:
Items in OpenAccess@KRIBB are protected by copyright, with all rights reserved, unless otherwise indicated.