Carrier-mediated transport of folate in a mutant of Pediococcus cerevisiae.
A mutant strain of Pediococcus cerevisiae (P. cerevisiae/PteGlu) was isolated which grows on low-folate (PteGlu) concentrations (200 pg/ml). The growth response of the parent and mutant strains to folinate (5-CHO-H(4)PteGlu) was the same. The transport of (14)C-PteGlu by P. cerevisiae/PteGlu was temperature-dependent (Q(10) between 27 C and 37 C was about 2), energy-dependent, and pH-dependent and was inhibited by iodoacetate, 2,4-dinitrophenol, potassium fluoride, and sodium azide. The uptake obeyed saturation kinetics with an apparent K(m) of 6.6 x 10(-6) M and V(max) of 4.0 x 10(-10) mol per min per mg (dry weight). At the steady state the intracellular concentration of PteGlu was 120-fold higher from that of the medium. Reduced folates like 5-CHO-H(4)PteGlu and methyl-tetrahydrofolate (5-CH(3)-H(4)PteGlu) as well as 2,4-diaminoanalogues (amethopterin and aminopterin) were shown to compete for the PteGlue-carrier.
D000630:Aminopterin / Q000494:pharmacology; D001386:Azides / Q000494:pharmacology; D001693:Biological Transport, Active; D002247:Carbon Isotopes; D002854:Chromatography, Paper; D003470:Culture Media; D004140:Dinitrophenols / Q000494:pharmacology; D005459:Fluorides / Q000494:pharmacology; D005492:Folic Acid / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007461:Iodoacetates / Q000494:pharmacology; D002955:Leucovorin / Q000378:metabolism; D008727:Methotrexate / Q000494:pharmacology; D009154:Mutation; D010376:Pediococcus / Q000254:growth & development / Q000378:metabolism*; D013696:Temperature; D013763:Tetrahydrofolates / Q000378:metabolism
D001386:Azides; D002247:Carbon Isotopes; D003470:Culture Media; D004140:Dinitrophenols; D007461:Iodoacetates; D013763:Tetrahydrofolates; D005492:Folic Acid; D000630:Aminopterin; D002955:Leucovorin; D005459:Fluorides; D008727:Methotrexate