Synthesis of Vitamin B6 by a Mutant of Escherichia coli K12 and the Action of 4'-Deoxypyridoxine

Scott, Thomas Allan; Hockney, Robert C.

doi:10.1099/00221287-110-2-285

Cited by 3 publications

(10 citation statements)

References 9 publications

(9 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar to rich medium, the B 6 auxotrophs exhibit a sensitivity phenotype on minimal media supplemented with B 6 that was visualized as a zone of growth inhibition, but this phenotype was influenced by both the concentration and identity of the supplemented vitamer (). By increasing the concentration of supplemented PN from 1 µM to 5 µM the zone of growth inhibition decreases in diameter, suggesting that in agreement with previous findings, 4dPN may competitively inhibit the uptake of exogenous PN by vitamin B 6 auxotrophs [19]. Additionally, no 4dPN sensitivity was seen in either mutant on minimal medium supplemented with PL, suggesting that 4dPN inhibits uptake of PN specifically ().…”

Section: Resultssupporting

confidence: 88%

“…To date, no enzymatic function has been identified for YggS or its homologs, but an E. coli yggS knockout mutant has significantly altered intracellular amino acid pools [17] and exhibits a PN sensitivity phenotype that likely results from the phosphorylation of imported PN and subsequent accumulation of intracellular pyridoxine 5′-phosphate (PNP) [18]. 4-Deoxypyridoxine (4dPN) is a PN analogue and vitamin B 6 -antimetabolite that has been reported to competitively inhibit uptake of extracellular B 6 [12,19]. Additionally, pioneering studies from the 1950-80s showed that 4dPN was transported into many cell types, including E. coli cells, and that its presence inhibited the activity of PLP-dependent enzymes [19].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

4′-Deoxypyridoxine disrupts vitamin B6 homeostasis in Escherichia coli K12 through combined inhibition of cumulative B6 uptake and PLP-dependent enzyme activity

et al. 2023

View full text Add to dashboard Cite

Pyridoxal 5′-phosphate (PLP) is the active form of vitamin B6 and a cofactor for many essential metabolic processes such as amino acid biosynthesis and one carbon metabolism. 4’-deoxypyridoxine (4dPN) is a long known B6 antimetabolite but its mechanism of action was not totally clear. By exploring different conditions in which PLP metabolism is affected in the model organism Escherichia coli K12, we showed that 4dPN cannot be used as a source of vitamin B6 as previously claimed and that it is toxic in several conditions where vitamin B6 homeostasis is affected, such as in a B6 auxotroph or in a mutant lacking the recently discovered PLP homeostasis gene, yggS. In addition, we found that 4dPN sensitivity is likely the result of multiple modes of toxicity, including inhibition of PLP-dependent enzyme activity by 4’-deoxypyridoxine phosphate (4dPNP) and inhibition of cumulative pyridoxine (PN) uptake. These toxicities are largely dependent on the phosphorylation of 4dPN by pyridoxal kinase (PdxK).

show abstract

Section: Resultssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

4′-Deoxypyridoxine disrupts vitamin B6 homeostasis in Escherichia coli K12 through combined inhibition of cumulative B6 uptake and PLP-dependent enzyme activity

et al. 2023

View full text Add to dashboard Cite

show abstract

“…To ensure that resistant strains were not glucosamine uptake mutants, complete medium containing maltose and supplemented with ~-[6-~H]glucosamine (1.5 g 1-l, specific activity 54 GBq mol-l) was inoculated with saline-washed wild-type NCYC 1026 or mutants Gam-1 or Gam-3, grown for 24 h in complete medium containing maltose, and incubated at 30 "C. After 24 h, uptake of ~-[6-~H]glucosamine was determined as previously described (Scott & Hockney, 1979). For competition experiments between maltose and glucosamine the maltose concentration in complete medium was varied from 10 to 100 g 1-1.…”

Section: Methodsmentioning

confidence: 99%

Gratuitous Catabolite Repression by Glucosamine of Maltose Utilization in Saccharomyces cerevisiae

Hockney¹,

Freeman²

1980

Microbiology

Self Cite

View full text Add to dashboard Cite

Glucosamine acted as a gratuitous catabolite repressor of maltose utilization in Saccharomyces cerevisiae. This repression was relieved in a linear manner as the maltose concentration was increased. Three mutants were isolated in which maltose utilization was no longer repressed by glucosamine. One of these mutants may be generally deficient in catabolite repression since it was not defective in glucosamine transport but was insensitive to glucosamine repression on all catabolite repressible carbon sources tested. Each mutant possessed a maltose uptake system which was notably less sensitive to glucose repression than that of the wild-type strain. These results are discussed in terms of a proposed model for regulation of maltose utilization in S. cerevisiae.

show abstract

“…This might suggest that the gene encoding pyridoxine phosphate oxidase is highly susceptible to mutation, but the more likely cause is cross-feeding during enrichment. During vitamin B6 starvation of auxotrophs prior to addition of penicillin, 'Oxidase' mutants excrete pyridoxine into the medium (Scott & Hockney, 1979). On addition of penicillin, many 'Pre Pn' mutants will be growing on this pyridoxine and therefore subject to sterilization.…”

Section: Discussionmentioning

confidence: 99%

“…requirement as ' Oxidase ' mutants synthesized vitamin B6 at an elevated rate (Fig. lb); this material was shown to be pyridoxine (Scott & Hockney, 1979). None of the 'Pre Pn' mutants synthesized vitamin B6 (Fig.…”

Section: R E S U L T Smentioning

confidence: 99%

The Isolation and Characterization of Three Types of Vitamin B6 Auxotrophs of Escherichia coli K12

Hockney

Scott

1979

Journal of General Microbiology

Self Cite

View full text Add to dashboard Cite

Approximately 500 vitamin B6 auxotrophs were isolated from 18 independent cultures of Escheric/iia coli strain CR63. None grew in minimal medium supplemented with 2'-hydroxypyridoxine. Eighteen auxotrophs which had arisen independently were further characterized. All of them were defective in vitamin B6 synthesis rather than in an aminotransferase involved in vitamin B6 utilization. Two different phenotypes were recognized : ' Oxidase ' mutants which grew only when supplied with pyridoxal or pyridoxal 5'-phosphate and ' Pre Pn ' mutants which would also grow with pyridoxine or pyridoxine phosphate. ' Oxidase' mutants were confined to a single linkage group, but data from interrupted mating experiments established that 'Pre Pn' mutants fall into two linkage groups which are possibly identical to pdxA and pdxB. All mutations in the pdxA region were allelic rather than located in two closely linked genes.

show abstract

Synthesis of Vitamin B6 by a Mutant of Escherichia coli K12 and the Action of 4'-Deoxypyridoxine

Cited by 3 publications

References 9 publications

4′-Deoxypyridoxine disrupts vitamin B6 homeostasis in Escherichia coli K12 through combined inhibition of cumulative B6 uptake and PLP-dependent enzyme activity

4′-Deoxypyridoxine disrupts vitamin B6 homeostasis in Escherichia coli K12 through combined inhibition of cumulative B6 uptake and PLP-dependent enzyme activity

Gratuitous Catabolite Repression by Glucosamine of Maltose Utilization in Saccharomyces cerevisiae

The Isolation and Characterization of Three Types of Vitamin B6 Auxotrophs of Escherichia coli K12

Contact Info

Product

Resources

About