Dihydrofolate Reductase in
            <i>Pediococcus cerevisiae</i>
            Strains Susceptible and Resistant to Amethopterin

Mandelbaum-Shavit, Frederika; Grossowicz, N.

doi:10.1128/aac.6.3.369

Cited by 7 publications

(6 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2). Another Fol+ mutant, which was described previously as a pteroyl-glutamic acid (pte-glu) strain (15), was directly selected for folate use and showed a similar growth pattern on folic acid (Fig. 2).…”

Section: Resultsmentioning

confidence: 99%

“…When this method was used, the culture was selectively enriched for mutants with the following characteristics: (i) an absolute requirement for exogenously supplied thymidine due to the loss of thymidylate synthetase activity (deprivation of thymidine causes thymineless death); (ii) a new ability to take up and grow on picogram quantities of unreduced folic acid in place of folinate; and (iii) high resistance to the folate analogs aminopterin and methotrexate. The Fol+ strain (the pte-glu strain of Mandelbaum-Shavit and Grossowicz [15]), which was isolated in the absence of any folate analog, and the Thy' Fol+ revertant, which was exposed to a folate analog in its history (when its Thy-Fol+ parent was isolated), were much more sensitive to aminopterin and methotrexate than the Thy-Fol+ mutant. Bertino and Stacey (1) showed that mutation to thymine dependence entails increased resistance to the folate analogs aminopterin and trimethoprim.…”

Section: Discussionmentioning

confidence: 99%

“…x 10-9 5 x 1O-9 Spontaneous mutant mutant of the wild type a UV mutagenesis and the selection procedure for the Thy-Fol+ mutant and the Thy+ Fol+ revertant are described in the text. The Fol+ strain was obtained by direct selection, as described by Mandelbaum-Shavit and Grossowicz(15). b Expressed as the methotrexate concentration (molar) which produced an optical density at 600 nm of 0.J.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Physiological and enzymatic properties of a thymidine-requiring Pediococcus cerevisiae mutant

Ariel¹,

Lavi²,

Holtzer³

et al. 1982

J Bacteriol

View full text Add to dashboard Cite

We describe the isolation and characterization of a Pediococcus cerevisiae thymidine-requiring mutant and its thymidine-independent revertant. The mutant strain lacked thymidylate synthetase activity and had an absolute requirement for low concentrations (2 ,ug/ml) of thymidine in addition to a requirement for N-5formyl tetrahydrofolic acid (folinate). Even at high concentrations (up to 500 ,ug/ ml), thymine could not replace thymidine. In contrast to its wild-type parent, which grows only on folinate, the thymidine-requiring mutant (Thy-Fol+) was able to take up and grow on picogram quantities of unreduced folic acid. When both strains were grown on folinate, the Thy-Fol+ strain was at least 103-fold more resistant to the folic acid analogs aminopterin and methotrexate than the wild-type strain. On the other hand, when grown on folic acid, the Thy-Fol+ strain was as sensitive to the folic acid analogs as the Thy' Fol+ strain and was 102-fold more sensitive than the wild-type strain grown on folinate. The thymidine-independent revertant (Thy' Fol+) regained the wild-type level of thymidylate synthetase activity, but maintained the ability to take up and grow on unreduced folic acid like its Thy-Fol+ parent.on August 1, 2020 by guest

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Physiological and enzymatic properties of a thymidine-requiring Pediococcus cerevisiae mutant

Ariel¹,

Lavi²,

Holtzer³

et al. 1982

J Bacteriol

View full text Add to dashboard Cite

show abstract

“…When this method was used, the culture was selectively enriched for mutants with the following characteristics: (i) an absolute requirement for exogenously supplied thymidine due to the loss of thymidylate synthetase activity (deprivation of thymidine causes thymineless death); (ii) a new ability to take up and grow on picogram quantities of unreduced folic acid in place of folinate; and (iii) high resistance to the folate analogs aminopterin and methotrexate. The Fol+ strain (the pte-glu strain of Mandelbaum-Shavit and Grossowicz [15]), which was isolated in the absence of any folate analog, and the Thy' Fol+ revertant, which was exposed to a folate analog in its history (when its Thy-Fol+ parent was isolated), were much more sensitive to aminopterin and methotrexate than the Thy-Fol+ mutant. a UV mutagenesis and the selection procedure for the Thy-Fol+ mutant and the Thy+ Fol+ revertant are described in the text.…”

Section: Discussionmentioning

confidence: 99%

Physiological and Enzymatic Properties of a Thymidine-Requiring Pediococcus cerevisiae Mutant

1982

J Bacteriol

View full text Add to dashboard Cite

show abstract

“…P. cerevisiae is less susceptible to aminopterin than the other lactobacilli, despite similar h5o values of the enzymes. This is also true for methotrexate (9) and can be explained by the uptake properties of P. cerevisiae (15).…”

Section: Discussionmentioning

confidence: 99%

Dihydrofolate Reductases in Some Folate-Requiring Bacteria with Low Trimethoprim Susceptibility

Then

Riggenbach

1978

Antimicrob Agents Chemother

View full text Add to dashboard Cite

Dihydrofolate reductases from the folate-requiring strains Streptococcus faecalis ATCC 8043, Lactobacillus casei ATCC 7496, and Pediococcus cerevisiae ATCC 8081, as well as from Lactobacillus arabinosus, which is not dependent on exogenous folate, were isolated, and their properties were compared to reductases of Escherichia coli B, Staphylococcus aureus, and rat liver reductase. An inhibition profile with six different inhibitors revealed significant differences among all enzymes. All lactobacilli reductases are less sensitive to trimethoprim than the enzymeA of E. coli and S. aureus, the reductase of P. cerevisiae requiring a concentration at least 1,000 times higher for 50% inhibition. Inhibition of growth of S. faecalis by pyrimethanmine and 2,4-diamino-6,7-diisopropyl-pteridine was seen to be much stronger than was predicted from the enzymatic data.Strains such as Streptococcus faecalis, Pediococcus cerevisiae, and Lactobacillus casei are often used for evaluating and characterizing antifolate compounds (e.g., references 9, 10, and 21). They are unable to synthesize their own folate cofactors and require preformed folates or, as in the case of P. cerevisiae, reduced folates for growth. These strains are therefore also used for very sensitive assays of several folate compounds, as they differ in their ability to utilize particular derivatives. They are strongly inhibited by antifolate compounds such as methotrexate or aminopterin, which may be actively transported (14, 27). In P. cerevisiae, the uptake system has been shown to be not identical with that for the transport offolinate (13). The strains are of course resistant to sulfonamides which interfere with the biosynthesis of dihydrofolate at dihydropteroate synthetase.During work on dihydrofolate reductases (EC 1.5.1.3) of different bacteria, investigated as target sites for trimethoprim-like compounds, we also studied the reductases of some folate-requiring strains, since their folate auxotrophy suggested possible alterations in this enzyme as well. Dihydrofolate reductases from S. faecalis ATCC 8043 (syn. S. faecium var. durans), P. cerevisiae ATCC 8081, L. casei ATCC 7496, and L. arabinosus ATCC 8014, which, however, is not dependent on exogenous folate, were partially purified and their response to some structurally different inhibitors was compared to that of the enzymes from Escherichia coli B, Staphylococcus aureus, and also to rat liver enzyme as an example of an eucaryotic enzyme. Inhibition profiles, which have been successfully used for detecting subtle differences in dihydrofolate reductases of different origin (e.g., reference 6), revealed major differences in these enzymes. MATERIALS AND METHODSPropagation of celli. Cells were grown in batches of 200 ml up to 6 liters in either Erlenmeyer flasks under agitation or, in the case of the lactobacilli, without agitation. The following media were used: sensitivity test broth (Oxoid Ltd., London, England) for E. coli B, S. aureus, and S. faecalis; lactobacilli AOAC broth (Difco Laboratories, Detro...

show abstract

Dihydrofolate Reductase in Pediococcus cerevisiae Strains Susceptible and Resistant to Amethopterin

Cited by 7 publications

References 16 publications

Physiological and enzymatic properties of a thymidine-requiring Pediococcus cerevisiae mutant

Physiological and enzymatic properties of a thymidine-requiring Pediococcus cerevisiae mutant

Physiological and Enzymatic Properties of a Thymidine-Requiring Pediococcus cerevisiae Mutant

Dihydrofolate Reductases in Some Folate-Requiring Bacteria with Low Trimethoprim Susceptibility

Contact Info

Product

Resources

About