title: Implication of gluconate kinase activity in L-ornithine biosynthesis in Corynebacterium glutamicum.
abstract: With the purpose of generating a microbial strain for L-ornithine production in Corynebacterium glutamicum, genes involved in the central carbon metabolism were inactivated so as to modulate the intracellular level of NADPH, and to evaluate their effects on L-ornithine production in C. glutamicum. Upon inactivation of the 6-phosphoglucoisomerase gene (pgi) in a C. glutamicum strain, the concomitant increase in intracellular NADPH concentrations from 2.55 to 5.75 mmol g⁻¹ (dry cell weight) was accompanied by reduced growth rate and L-ornithine production, suggesting that L-ornithine production is not solely limited by NADPH availability. In contrast, inactivation of the gluconate kinase gene (gntK) led to a 51.8 % increase in intracellular NADPH concentration, which resulted in a 49.9 % increase in L-ornithine production. These results indicate that excess NADPH is not necessarily rate-limiting, but is required for increased L-ornithine production in C. glutamicum.
authors.affiliation: Department of Pharmaceutical Engineering, College of Health Science, Sangji University, Sangjidae-gil 83, Wonju-si, Gangwon-do 220-702, Korea.
authors.forename: Gui-Hye
authors.initials: GH
authors.lastname: Hwang
authors.forename: Jae-Yong
authors.initials: JY
authors.lastname: Cho
mesh_terms: D048230:Corynebacterium glutamicum / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D017353:Gene Deletion; D005956:Glucose-6-Phosphate Isomerase / Q000235:genetics; D009249:NADP / Q000096:biosynthesis / Q000378:metabolism; D009952:Ornithine / Q000096:biosynthesis* / Q000378:metabolism; D010427:Pentose Phosphate Pathway; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*
chemical_list: D009249:NADP; D009952:Ornithine; D017853:Phosphotransferases (Alcohol Group Acceptor); C020578:gluconokinase; D005956:Glucose-6-Phosphate Isomerase