Identification of a new tetrameric pyridoxal 4-dehydrogenase as the second enzyme in the degradation pathway for pyridoxine in a nitrogen-fixing symbiotic bacterium, Mesorhizobium loti

Yokochi, Nana; Nishimura, Saki; Yoshikane, Yu; Ohnishi, Kouhei; Yagi, Toshiharu

doi:10.1016/j.abb.2006.06.002

Cited by 22 publications

(19 citation statements)

References 26 publications

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“…Recombinant PL 4-dehydrogenase (PLDH), PM-pyruvate aminotransferase (PPAT), and PN 4-oxidase (PNOX) were prepared as described previously (10–12). Recombinant E. coli alkaline phosphatase (ALP) was prepared according to a standard protocol (13).…”

Section: Methodsmentioning

confidence: 99%

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All-enzymatic HPLC method for determination of individual and total contents of vitamin B₆ in foods

Viet¹,

Ide²,

Mugo³

et al. 2012

Food & Nutrition Research

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BackgroundThere is a need for a reliable and accurate method for quantification of each of the seven individual vitamin B6 compounds including pyridoxine-β-glucoside in foods.ObjectiveTo determine pyridoxal (PL), pyridoxamine (PM), pyridoxine (PN), pyridoxal 5′-phosphate (PLP), pyridoxamine 5′-phosphate (PMP), pyridoxine 5′-phosphate (PNP), and pyridoxine-β-glucoside (PNG) in foods.DesignBy specific enzymatic treatment, each of the seven vitamin B6 compounds was all converted into 4-pyridoxolactone, which is a highly fluorescent compound. In total, seven separate, enzymatic steps were performed for each sample. Separation and quantification were performed with reversed-phase high performance liquid chromatography (HPLC) coupled with fluorescence detection. For each sample type the result was corrected for the recovery based on spiked samples. The method was applied for analyses of chicken liver, chicken white meat, egg yolk, egg white, dried anchovy, carrots, and garlic.ResultsThe recovery varied from 14 to 114% in chicken liver, chicken white meat, egg yolk, egg white, dried anchovy, carrot, and garlic. Each food showed a characteristic distribution of the seven vitamin B6 compounds. The PNG was only found in low amounts; that is, 17–29nmol vitamin B6/g in the plant-derived foods, carrot and garlic. Only egg white showed a lower content, 3nmol/g. Overall the content in chicken liver, chicken white meat, and egg yolk had a total content of vitamin B6 between 42 and 51nmol/g. Both PM and PMP were high in the chicken liver. In contrast, PL and PLP were high in the chicken white meat. The main vitamin B6 in the egg yolk was PLP. The dried anchovy contained high amounts of PLP and PMP and a total content of 144nmol/g.ConclusionsThe enzymatic-based HPLC method was applied for the determination of seven vitamin B6 compounds in foods. Their distribution in the foods varied significantly.

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Section: Methodsmentioning

confidence: 99%

“…The PLDH (10), PNOX (12), PPAT (11), ALP (16), and β-glucosidase (17) were assayed as described previously. One unit of enzyme was defined as the amount that catalyzed the formation of 1µmol of product per min.…”

Section: Methodsmentioning

confidence: 99%

All-enzymatic HPLC method for determination of individual and total contents of vitamin B₆ in foods

Viet¹,

Ide²,

Mugo³

et al. 2012

Food & Nutrition Research

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“…Pyridoxine, pyridoxamine, and pyridoxal are specifically converted into 4-pyridoxolactone by three enzymes involved in the degradation pathway for vitamin B 6 , and then 4-pyridoxolactone is determined by reversed-phase isocratic HPLC. Pyridoxal is converted into 4-pyridoxolactone by pyridoxal 4-dehydrogenase, which catalyzes the irreversible oxidation of pyridoxine to 4-pyridoxolactone ( 14 ). Pyridoxine is converted into 4-pyridoxolactone through a coupling reaction involving pyridoxine 4-oxidase ( 12 ) and pyridoxal 4-dehydrogenase: both reactions are irreversible.…”

Section: Strategymentioning

confidence: 99%

Determination of Individual Vitamin B<sub>6</sub> Compounds Based on Enzymatic Conversion to 4-Pyridoxolactone

Nishimura

Nagano

Crai

et al. 2008

J Nutr Sci Vitaminol

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Summary A determination method for individual natural vitamin B 6 compounds was developed. The vitamin B 6 compounds were specifically converted into 4-pyridoxolactone (PAL), a highly fluorescent compound, through a combination of enzymatic reactions and HCl-hydrolysis. PAL was then determined by HPLC. Pyridoxal was completely oxidized to PAL with pyridoxal 4-dehydrogenase (PLDH). Pyridoxine and pyridoxamine were totally converted into PAL through a coupling reaction involving pyridoxine 4-oxidase and PLDH, and one involving pyridoxamine-pyruvate aminotransferase and PLDH, respectively. The 5 ¢ -phosphate forms and pyridoxine-␤ -glucoside were hydrolyzed with HCl, and then determined as their free forms. Pyridoxine 5 ¢ -phosphate and pyridoxine-␤ -glucoside were not separately determined here. Three food samples were analyzed by this method. Key Words vitamin B 6 , 4-pyridoxolactone, pyridoxal 4-dehydrogenase, pyridoxine 4-oxidase, pyridoxamine-pyruvate aminotransferase There are six natural forms of vitamin B 6 : pyridoxine, pyridoxal, pyridoxamine, pyridoxine 5 ¢ -phosphate, pyridoxal 5 ¢ -phosphate, and pyridoxamine 5 ¢ -phosphate ( Fig. 1). In addition, plants contain pyridoxine-␤ -glucoside, a storage form of vitamin B 6 ; it is not counted as vitamin B 6 because its nutritional availability as a form of vitamin B 6 in the human body is controversial ( 1 ). The above six vitamin B 6 compounds have identical nutritional functions. On the other hand, recent studies have shown that individual vitamin B 6 compounds exhibit specific biochemical functions; pyridoxamine, in particular, can detoxify active carbonyl products and is undergoing a phase II clinical trial for the treatment of complications of diabetes ( 2 ). Vitamin B 6 compounds are strong quenchers of singlet oxygen ( 3 ), and pyridoxal 5 ¢ -phosphate and pyridoxamine 5 ¢ -phosphate, coenzyme forms of vitamin B 6 , show stronger protection of yeast cells from oxidative death than vitamin C, a representative antioxidative vitamin ( 4 ). Thus, the development of a method for the determination of individual vitamin B 6 compounds plus pyridoxine-␤ -glucoside in foods is required to estimate their functionality.Although many methods have been developed for the determination of individual vitamin B 6 compounds, no method can be satisfactorily applied to the analysis of food samples. Thus, a microbioassay involving a budding yeast, Saccharomyces cerevisiae (former name, S. uvarum ), which was developed about 40 y ago ( 5 ), has been used to determine the total content of vitamin B 6 in food samples; in the figure, the content of pyridoxine-␤ -glucoside is included because food samples are prehydrolyzed with HCl for the microbioassay, and pyridoxine-␤ -glucoside in the samples is converted into pyridoxine. The best method so far developed for individual determination may be cation-exchange HPLC with a fluorescence detection system ( 6 ), which is applicable to biological samples, such as serum, brain, liver, milk and so on, from experimental animals. The seco...

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“…Previously, the genes encoding pyridoxine-4-oxidase (mlr6785), 4-pyridoxolactonase (mlr6805), pyridoxal-4-dehydrogenase (mlr6807) and the 2-methyl-3-hydroxypyridine-5-carboxylic acid oxygenase (mlr6788) were identified in Mesorhizobium loti MAFF303099 (3)(4)(5)(6). Recently we have reported the identification of a fifth gene (mlr6793), encoding 4-pyridoxic acid dehydrogenase (7).…”

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Gene Identification and Structural Characterization of the Pyridoxal 5‘-Phosphate Degradative Protein 3-Hydroxy-2-methylpyridine-4,5-dicarboxylate Decarboxylase from Mesorhizobium loti MAFF303099^,

et al. 2007

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The function of the mlr6791 gene from Mesorhizobium loti MAFF303099 has been identified. This gene encodes 3-hydroxy-2-methylpyridine-4,5-dicarboxylate decarboxylase (HMPDdc), an enzyme involved in the catabolism of pyridoxal 5-phosphate (Vitamin B 6 ). This enzyme was overexpressed in Escherichia coli and characterized. HMPDdc is a 26 kDa protein that catalyzes the decarboxylation of 3-hydroxy-2-methylpyridine-4,5-dicarboxylate to 3-hydroxy-2-methylpyridine-5-carboxylate. The K M and k cat were found to be 366 μM and 0.6 s -1 respectively. The structure of this enzyme was determined at 1.9 Å resolution using SAD phasing and belongs to the class II aldolase/adducin superfamily. While the decarboxylation of hydroxy-substituted benzene rings is a common motif in biosynthesis, the mechanism of this reaction is still poorly characterized. The structural studies described here suggest that catalysis of such decarboxylations proceeds by an aldolase-like mechanism.In contrast to our understanding of cofactor biosynthetic pathways, very little is known about cofactor catabolism. Cofactor catabolism is likely to be rare because cofactors are trace metabolites and therefore not good food sources for bacteria. Pyridoxine, 1 (vitamin B 6 ) catabolism is the best understood cofactor catabolic pathway and a small number of bacteria that can grow on vitamin B 6 as the sole source of carbon and nitrogen have been identified (1). Two catabolic pathways have been proposed (2). In the first pathway Figure 1, (pathway A), found in Pseudomonas sp. vitamin B 6 is degraded in eight steps to form succinic semialdehyde, 9, while in the second pathway (pathway B) observed in Pseudomonas IA and in Arthrobacter Cr-7, vitamin B 6 is catabolized in seven steps to 2-(hydroxymethyl)-4-oxobutanoate, 14. A related catabolic pathway in Mesorhizobium loti MAFF303099 which is very similar to the degradative pathway A has recently been discovered. 3-hydroxy-2-methylpyridine-5-carboxylate, 7 is an intermediate in this catabolic pathway. The gene coding for the enzyme producing this metabolite has not previously been discovered and is the subject of this paper.Previously, the genes encoding pyridoxine-4-oxidase (mlr6785), 4-pyridoxolactonase (mlr6805), pyridoxal-4-dehydrogenase (mlr6807) and the 2-methyl-3-hydroxypyridine-5-carboxylic acid oxygenase (mlr6788) were identified in Mesorhizobium loti MAFF303099 (3-6). Recently we have reported the identification of a fifth gene (mlr6793), encoding 4-* To whom correspondence should be addressed at the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853. Telephone: (607) 255-4137. E-mail: tpb2@cornell.edu or see3@cornell.edu # These authors contributed equally to the research reported in this paper. ‡ The Brookhaven Protein Data Bank code is 2Z7B. pyridoxic acid dehydrogenase (7). These genes are not part of an operon, but are all close to each other on the M. loti chromosome, Figure 1. This suggested that other PLP catabolic genes might also be found in this r...

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Identification of a new tetrameric pyridoxal 4-dehydrogenase as the second enzyme in the degradation pathway for pyridoxine in a nitrogen-fixing symbiotic bacterium, Mesorhizobium loti

Cited by 22 publications

References 26 publications

All-enzymatic HPLC method for determination of individual and total contents of vitamin B₆ in foods

All-enzymatic HPLC method for determination of individual and total contents of vitamin B₆ in foods

Determination of Individual Vitamin B<sub>6</sub> Compounds Based on Enzymatic Conversion to 4-Pyridoxolactone

Gene Identification and Structural Characterization of the Pyridoxal 5‘-Phosphate Degradative Protein 3-Hydroxy-2-methylpyridine-4,5-dicarboxylate Decarboxylase from Mesorhizobium loti MAFF303099^,

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Identification of a new tetrameric pyridoxal 4-dehydrogenase as the second enzyme in the degradation pathway for pyridoxine in a nitrogen-fixing symbiotic bacterium, Mesorhizobium loti

Cited by 22 publications

References 26 publications

All-enzymatic HPLC method for determination of individual and total contents of vitamin B6 in foods

All-enzymatic HPLC method for determination of individual and total contents of vitamin B6 in foods

Determination of Individual Vitamin B<sub>6</sub> Compounds Based on Enzymatic Conversion to 4-Pyridoxolactone

Gene Identification and Structural Characterization of the Pyridoxal 5‘-Phosphate Degradative Protein 3-Hydroxy-2-methylpyridine-4,5-dicarboxylate Decarboxylase from Mesorhizobium loti MAFF303099,

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All-enzymatic HPLC method for determination of individual and total contents of vitamin B₆ in foods

All-enzymatic HPLC method for determination of individual and total contents of vitamin B₆ in foods

Gene Identification and Structural Characterization of the Pyridoxal 5‘-Phosphate Degradative Protein 3-Hydroxy-2-methylpyridine-4,5-dicarboxylate Decarboxylase from Mesorhizobium loti MAFF303099^,