Investigation of 1-Deoxy-D-Xylulose 5-Phosphate Synthase and Transketolase of Bacillus subtilis in Relation to Vitamin B6 Biosynthesis

Sakai, Akihiro; Kinoshita, Natsumi; Kita, Michiyuki; Katsuragi, Tohoru; Tani, Yoshiki

doi:10.3177/jnsv.49.73

Cited by 6 publications

(6 citation statements)

References 15 publications

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“…Due to its wide substrate specificity the enzyme is involved in the catabolism of pentose sugars, in the formation of D-ribose 5-phosphate, and in the provision of D-erythrose 4-phosphate, a precursor of aromatic amino acids, aromatic vitamins, and pyridoxine (59). Since 4-(phosphohydroxy)-L-threonine and 1-deoxy-D-xylulose 5-phosphate are believed to be direct precursors of vitamin B6 in E. coli, and transketolase catalyses the formation of each precursor, vitamin B6 may be important for in vivo survival of APEC (57).…”

Section: Lipopolysaccharide (Lps) Contributes To Viability Of Apec Inmentioning

confidence: 99%

Identification of Genes Required for Avian Escherichia coli Septicemia by Signature-Tagged Mutagenesis

et al. 2005

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Infections with avian pathogenic Escherichia coli (APEC) cause colibacillosis, an acute and largely systemic disease resulting in significant economic losses in poultry industry worldwide. Although various virulenceassociated genes have been identified in APEC, their actual role in pathogenesis is still not fully understood, and, furthermore, certain steps of the infection process have not been related to previously identified factors. Here we describe the application of a signature-tagged transposon mutagenesis (STM) approach to identify critical genes required for APEC infections in vivo. Twenty pools of about 1,800 IMT5155 (O2:H5) mutants were screened in an infection model using 5-week-old chickens, and potentially attenuated mutants were subjected to a secondary screen and in vivo competition assays to confirm their attenuation. A total of 28 genes required for E. coli septicemia in chickens were identified as candidates for further characterization. Among these disrupted genes, six encode proteins involved in biosynthesis of extracellular polysaccharides and lipopolysaccharides; two encode iron transporters that have not been previously characterized in APEC in in vivo studies, and four showed similarity to membrane or periplasmic proteins. In addition, several metabolic enzymes, putative proteins with unknown function, and open reading frames with no similarity to other database entries were identified. This genome-wide analysis has identified both novel and previously known factors potentially involved in pathogenesis of APEC infection.Escherichia coli typically colonizes the avian gastrointestinal tract and other mucosal surfaces. While most strains are commensal, certain strains designated avian pathogenic E. coli (APEC) have the ability to cause severe disease. Predominant serotypes of APEC are O1:K1, O2:K1, and O78:K80 (7,13,18,26). APECs most likely enter and colonize the avian respiratory tract by inhalation of fecal dust, leading to localized infections such as airsacculitis and pneumonia. In certain cases, they spread into various internal organs and typically cause pericarditis, perihepatitis, peritonitis, salpingitis, and other extraintestinal diseases. Colibacillosis of poultry is characterized in its acute form by septicemia, commonly resulting in sudden death (6).Several bacterial factors have been associated with the virulence of APEC, including adhesins, toxins, iron acquisition systems, colicin V plasmid, serum resistance proteins, and capsule as well as lipopolysaccharide complexes (15,21,37). However, the mechanisms underlying pathogenicity are still not fully understood, and only certain steps of the infection process can be accounted for by these known virulence factors. In recent years, genome-wide analyses have led to a better understanding of the molecular mechanisms of pathogenicity. New molecular approaches have also aided in the identification of genes involved in pathogenesis, including in vivo expression technology, selective capture of transcribed sequences (SCOTS), different...

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Section: Lipopolysaccharide (Lps) Contributes To Viability Of Apec Inmentioning

confidence: 99%

Identification of Genes Required for Avian Escherichia coli Septicemia by Signature-Tagged Mutagenesis

et al. 2005

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“…Most bacteria that have pdxS-and pdxT-like genes have dxs orthologs, but no orthologs of dxs can be found in the genomes of archaea, Staphylococcus aureus, or Streptococcus pneumoniae, all of which apparently utilize the PdxST pathway (data not shown). Moreover, the B. subtilis conditional dxs mutant was not impaired in B 6 synthesis (32). Additionally, the five-carbon-containing compound utilized for PLP synthesis in yeast is derived from glucose as an intact unit (13); in contrast, 1-deoxy-D-xylulose-5-phosphate originates from condensation of pyruvate and glyceraldehyde 3-phosphate (9,15).…”

Section: Figmentioning

confidence: 99%

Physical and Enzymological Interaction of Bacillus subtilis Proteins Required for De Novo Pyridoxal 5′-Phosphate Biosynthesis

Belitsky

2004

J Bacteriol

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Bacillus subtilis synthesizes pyridoxal 5-phosphate, the active form of vitamin B 6 , by a poorly characterized pathway involving the yaaD and yaaE genes. The pdxS (yaaD) mutant was confirmed to be a strict B 6 auxotroph, but the pdxT (yaaE) mutant turned out to be a conditional auxotroph depending on the availability of ammonium in the growth medium. The PdxS and PdxT proteins copurified during affinity chromatography and apparently form a complex that has glutaminase activity. PdxS and PdxT appear to encode the synthase and glutaminase subunits, respectively, of a glutamine amidotransferase of as-yet-unknown specificity essential for B 6 biosynthesis.

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“…A conditional mutant of dxs (encoding 1 -deoxy-D-xylulose forming enzyme, 1-deoxy-D-xylulose synthase) was constructed, and its property was investi gated. As a result, we found that the dxs mutant pro duces the same amount of B6 as the wild-type B. subtilis (52). Therefore, it is likely that dxs is not involved in B6 biosynthesis.…”

Section: Status Of 1-deoxy-d-xylulose and 4-hydroxy-l-threomentioning

confidence: 48%

“…Transketo lase (tkt), which catalyzes the D-erythrose 4-phosphate forming reaction was disrupted in B. subtilis. The tkt dis ruptant did not show B6 auxotrophy, and produced a normal amount of B6, suggesting that tkt is not involved in B6 biosynthesis in B, subtilis (52). SerC gene, which is probably involved in 4-hydroxy-L-threonine forming route in E. coil, was also investigated.…”

Section: Status Of 1-deoxy-d-xylulose and 4-hydroxy-l-threomentioning

confidence: 99%

Recent Progress of Vitamin B6 Biosynthesis

Sakai

Kita

Tani

2004

Journal of Nutritional Science and Vitaminology, J Nutr Sci Vit

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SummaryThis review is the current summary of vitamin B6 (B6) biosynthesis in Escheri chic coli and other microorganisms. The de novo biosynthesis of B6 has been studied exten sively for last three decades. However, the de novo biosynthesis of B6 still remains unclear in spite of its simple structure. For the first two decades, B6 biosynthesis had been mainly stud ied with E. coil using genetic, nutritional, and isotopic labeling experiments. According to these studies, some compounds including glycolaldehyde were identified as the precursor. During the last decade, gene manipulate techniques were rapidly developed, and complete genome sequences of some microorganisms became available. Using these new tools, valu able information has been provided. The complete DNA sequence of pdx genes and other genes, which are possibly involved in B6 biosynthesis, were shown. The roles of some genes and precursors were proposed. Besides E. coli, B6 biosynthesis in other microorganisms has been also studied. In some microorganisms, snz/sno was reported to be involved in B6 bio synthesis. Intriguingly, these genes show no similarity to any of the E. coil pdx genes, and are not found in E. coil. Microorganisms having snz/sno gene homologues lack homologues to pdxA/pdxJ genes, whereas those with homologues to pdxA/pdxJ lack snz/sno gene homo logues. Therefore, it is most likely that there are at least two kinds of B6 biosynthetic path ways in microorganisms. These studies provided important clues of B6 biosynthesis, but the entire picture of the B6 biosynthetic pathway remains unclear.

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Investigation of 1-Deoxy-D-Xylulose 5-Phosphate Synthase and Transketolase of Bacillus subtilis in Relation to Vitamin B6 Biosynthesis

Cited by 6 publications

References 15 publications

Identification of Genes Required for Avian Escherichia coli Septicemia by Signature-Tagged Mutagenesis

Identification of Genes Required for Avian Escherichia coli Septicemia by Signature-Tagged Mutagenesis

Physical and Enzymological Interaction of Bacillus subtilis Proteins Required for De Novo Pyridoxal 5′-Phosphate Biosynthesis

Recent Progress of Vitamin B6 Biosynthesis

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