title: Cloning and characterization of the dxs gene, encoding 1-deoxy-d-xylulose 5-phosphate synthase from Agrobacterium tumefaciens, and its overexpression in Agrobacterium tumefaciens.
abstract: A newly isolated gene dxs11 from Agrobacterium tumefaciens (KCCM 10413), an organism with potential for the industrial production of ubiquinone-10 (UbiQ(10)), encoding a 1-deoxy-d-xylulose 5-phosphate synthase (Dxs), was cloned in Escherichia coli and its nucleotide sequence was determined. DNA sequence analysis revealed an open reading frame of 1920bp, capable of encoding a polypeptide of 640 amino acids residues with a calculated isoelectric point of pH 5.63 and a molecular mass of 68,054Da. The homodimeric enzyme was overexpressed in E. coli and purified as an active soluble form. The enzyme required thiamine diphosphate and a divalent metal ion, either Mg(2+) or Mn(2+), for enzymatic activity. The enzyme had an optimal pH and temperature of 8.0 and 37 degrees C, respectively, with a k(cat) of 26.8s(-1) and a k(cat)/K(m) of 0.67 and 1.17s(-1)M(-1) for pyruvate and d-glyceraldehyde 3-phosphate, respectively. A. tumefaciens Dxs showed a comparable catalytic efficiency to other Dxs proteins. The dxs11 gene was transformed into A. tumefaciens KCCM 10413, and the resulting recombinant, A. tumefaciens pGX11, showed higher UbiQ(10) production (502.4mg/l) and content (8.3mg/gDCW) than A. tumefaciens KCCM 10413, by 21.9 and 23.9%, respectively. This work describes Dxs from A. tumefaciens, an organism with the potential for industrial UbiQ(10) production, and the first metabolic engineering study with the non-mevalonate pathway enzyme in A. tumefaciens.
authors.affiliation: Department of Chemical Engineering, Konkuk University, 1 Hwayang-Dong, Gwangjin-Gu, Seoul 143-701, Republic of Korea.
authors.forename: Jung-Kul
authors.initials: JK
authors.lastname: Lee
authors.forename: Deok-Kun
authors.initials: DK
authors.lastname: Oh
authors.forename: Sang-Yong
authors.initials: SY
authors.lastname: Kim
mesh_terms: D016960:Agrobacterium tumefaciens / Q000201:enzymology* / Q000235:genetics*; D003001:Cloning, Molecular; D004795:Enzyme Stability; D004926:Escherichia coli; D016297:Mutagenesis, Site-Directed; D015202:Protein Engineering; D014162:Transfection; D014166:Transferases / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D014451:Ubiquinone / Q000096:biosynthesis
chemical_list: D014451:Ubiquinone; D014166:Transferases; C109461:deoxyxylulose-5-phosphate synthase; C025204:Ubiquinone Q2