title: The nitrogen-fixing symbiotic bacterium Mesorhizobium loti has and expresses the gene encoding pyridoxine 4-oxidase involved in the degradation of vitamin B6.
abstract: The gene product of mll6785 of a nitrogen-fixing symbiotic bacterium Mesorhizobium loti MAFF303099 was identified as pyridoxine 4-oxidase, the first enzyme in the vitamin B6-degradation pathway. The gene was cloned and ligated into pET-21a+. Escherichia coli BL21(DE3) was co-transformed with the constructed plasmid plus pKY206 containing groESL genes encoding chaperonins. The overexpressed protein was purified to homogeneity by the ammonium sulfate fractionation and three chromatography steps. The enzymatic properties of the purified protein, such as K(m) values for pyridoxine (213+/-19 microM) and oxygen (78+/-10 microM), were compared to those of pyridoxine 4-oxidase from two bacteria with known vitamin B6-degradation pathway. M. loti grown in a Rhizobium medium showed the enzyme activity. The results suggest that M. loti also contains the degradation pathway of vitamin B6.
authors.affiliation: Department of Bioresources Science, Faculty of Agriculture, Nankoku, Kochi 783-8502, Japan.
authors.forename: Baiqiang
authors.initials: B
authors.lastname: Yuan
authors.forename: Yu
authors.initials: Y
authors.lastname: Yoshikane
authors.forename: Nana
authors.initials: N
authors.lastname: Yokochi
authors.forename: Kouhei
authors.initials: K
authors.lastname: Ohnishi
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Yagi
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D020561:Alphaproteobacteria / Q000201:enzymology* / Q000235:genetics*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009586:Nitrogen Fixation / Q000502:physiology*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity; D013559:Symbiosis; D013816:Thermodynamics; D025101:Vitamin B 6 / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D025101:Vitamin B 6; D000429:Alcohol Oxidoreductases; C487815:pyridoxine 4-oxidase