Resistance to Pediococcus cerevisiae to amethopterin as a consequence of changes in enzymatic activity and cell permeability. II. Permeability changes to amethopterin and other folates in the drug-resistant mutant.

@article{MandelbaumShavit1976ResistanceTP,
  title={Resistance to Pediococcus cerevisiae to amethopterin as a consequence of changes in enzymatic activity and cell permeability. II. Permeability changes to amethopterin and other folates in the drug-resistant mutant.},
  author={F. Mandelbaum-Shavit},
  journal={Biochimica et biophysica acta},
  year={1976},
  volume={428 3},
  pages={
          674-82
        }
}
the accumulation of amethopterin in a Pediococcus cerevisiae strain resistant to this analogue was about 30% of that in P. cerevisiae/PteGlu, the sensitive parent. The uptake in the resistant strain was strictly glucose dependent, whereas in the sensitive parent about 16% accumulation occurred in absence of glucose. The transport in both strains was inhibited by iodoacetate and KF. Amethopterin uptake exhibited saturation kinetics with an apparent Km of 5 muM in P. cerevisiae/AMr and 0.5 muM in… Expand
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Selection of Methotrexate-Resistant Lactobacillus Casei in the Presence of Folate or 5-Formyl-Tetrahydrofolate Affects the Resistance Mechanism
Reduced folate cofactors (H4PteGlu) are essential for the biosynthesis of purines, thymidine and some amino acids, thus the antimetabolites blocking their biochemical pathways (1) have been used as… Expand
Transport of folate compounds in bacterial and mammalian cells.

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TLDR
Dihydrofolate reductase from the wild type and aminopterin-resistant mutants of Diplococcus pneumoniae has been compared and it is found that Aminopterin resistance for such mutants is, therefore, not due to an alteration of the dihydrofolates reduct enzyme. Expand
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