title: Disruption of genes for the enhanced biosynthesis of α-ketoglutarate in Corynebacterium glutamicum.
abstract: The development of microbial strains for the enhanced production of α-ketoglutarate (α-KG) was investigated using a strain of  Corynebacterium glutamicum  that overproduces of l-glutamate, by disrupting three genes involved in the α-KG biosynthetic pathway. The pathways competing with the biosynthesis of α-KG were blocked by knocking out aceA (encoding isocitrate lyase, ICL), gdh (encoding glutamate dehydrogenase, l-gluDH), and gltB (encoding glutamate synthase or glutamate-2-oxoglutarate aminotransferase, GOGAT). The strain with aceA, gltB, and gdh disrupted showed reduced ICL activity and no GOGAT and l-gluDH activities, resulting in up to 16-fold more α-KG production than the control strain in flask culture. These results suggest that l-gluDH is the key enzyme in the conversion of α-KG to l-glutamate; therefore, prevention of this step could promote α-KG accumulation. The inactivation of ICL leads the carbon flow to α-KG by blocking the glyoxylate pathway. However, the disruption of gltB did not affect the biosynthesis of α-KG. Our results can be applied in the industrial production of α-KG by using C. glutamicum as producer.
authors.affiliation: Department of Bioscience and Biotechnology, Hankuk University of Foreign Studies, Yongin, Gyeonggi-Do, 449-791, Korea.
authors.forename: Jae-Hyung
authors.initials: JH
authors.lastname: Jo
authors.forename: Hye-Young
authors.initials: HY
authors.lastname: Seol
authors.forename: Yun-Bom
authors.initials: YB
authors.lastname: Lee
authors.forename: Min-Hong
authors.initials: MH
authors.lastname: Kim
authors.forename: Hyung-Hwan
authors.initials: HH
authors.lastname: Hyun
authors.forename: Hyune-Hwan
authors.initials: HH
authors.lastname: Lee
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics; D048230:Corynebacterium glutamicum / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D055786:Gene Knockout Techniques; D005798:Genes, Bacterial / Q000235:genetics*; D005969:Glutamate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D005970:Glutamate Synthase / Q000235:genetics / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006038:Glyoxylates / Q000378:metabolism; D007218:Industrial Microbiology; D007522:Isocitrate Lyase / Q000235:genetics / Q000378:metabolism; D007656:Ketoglutaric Acids / Q000378:metabolism*; D009154:Mutation
chemical_list: D006038:Glyoxylates; D007656:Ketoglutaric Acids; D018698:Glutamic Acid; D005970:Glutamate Synthase; D005969:Glutamate Dehydrogenase; D007522:Isocitrate Lyase