Metabolic Engineering of Pentose Phosphate Pathway in Ralstonia eutropha for Enhanced Biosynthesis of Poly--hy
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- 作者：Jin-Nam Lee ; Hyun-Dong Shin ; and Yong-Hyun Lee
- 刊名：Biotechnology Progress
- 出版年：2003
- 出版时间：October 2003
- 年：2003
- 卷：19
- 期：5
- 页码：1444 - 1449
- 全文大小：124K
- 年卷期：v.19,no.5(October 2003)
- ISSN：1520-6033
文摘
Poly-
-hydroxybutyrate (PHB) biosynthesis in Ralstonia eutropha from gluconate asa carbon source is carried out through the Entner-Doudoroff (ED) pathway and thepentose-phosphate (PP) pathway generating NADPH and glyceraldehyde-3-phosphatethat flows to acetyl-CoA, actively in the unbalanced PHB accumulation phase. Thegnd gene encoding 6-phosphogluconate dehydrogenase (6PGDH) and the tktA geneencoding the transketolase (TK) in PP pathway of E. coli were transformed into R.eutropha H16 to modify the metabolic flux of gluconate to the PHB biosynthesis. Over-generated NADPH by the amplified gnd gene tended to depress the cell growth andPHB concentration. Meanwhile, the amplified tktA gene significantly increased bothPHB biosynthesis and cell growth as a result of the effective flow of glyceraldehyde-3-phosphate into acetyl-CoA along with the concomitant supplementation of NADPH.The amplified tktA gene also activated the enzyme activities directly associated withPHB biosynthesis. The transformant R. eutropha harboring tktA gene was cultivatedusing pH-stat-fed-batch to achieve the overproduction of PHB.
-hydroxybutyrate (PHB) biosynthesis in Ralstonia eutropha from gluconate asa carbon source is carried out through the Entner-Doudoroff (ED) pathway and thepentose-phosphate (PP) pathway generating NADPH and glyceraldehyde-3-phosphatethat flows to acetyl-CoA, actively in the unbalanced PHB accumulation phase. Thegnd gene encoding 6-phosphogluconate dehydrogenase (6PGDH) and the tktA geneencoding the transketolase (TK) in PP pathway of E. coli were transformed into R.eutropha H16 to modify the metabolic flux of gluconate to the PHB biosynthesis. Over-generated NADPH by the amplified gnd gene tended to depress the cell growth andPHB concentration. Meanwhile, the amplified tktA gene significantly increased bothPHB biosynthesis and cell growth as a result of the effective flow of glyceraldehyde-3-phosphate into acetyl-CoA along with the concomitant supplementation of NADPH.The amplified tktA gene also activated the enzyme activities directly associated withPHB biosynthesis. The transformant R. eutropha harboring tktA gene was cultivatedusing pH-stat-fed-batch to achieve the overproduction of PHB.