Transport of 2-methyl-4-amino-5-hydroxymethylpyrimidine in Saccharomyces cerevisiae.
The transport of 2-methyl-4-amino-5-hydroxymethylpyrimidine (hydroxymethylpyrimidine) was studied in resting cells of Saccharomyces cerevisiae. Hydroxymethylpyrimidine uptake was an energy- and temperature-dependent process which has an optimal pH at 4.5. The apparent Km for hydroxymethylpyrimidine uptake was 0.37 microM, and the uptake was inhibited by 2-methyl-4-amino-5-aminomethylpyrimidine, thiamin and pyrithiamin. Furthermore, hydroxymethylpyrimidine uptake was inhibited by 4-azido-2-nitrobenzoylthiamin, a specific and irreversible inhibitor of the yeast thiamin transport system and it was greatly impaired in the thiamin transport mutant of S. cerevisiae. Thus, hydroxymethylpyrimidine is taken up by a common transport system with thiamin in S. cerevisiae, but in contrast to thiamin transport, accumulated hydroxymethylpyrimidine is released from yeast cells showing an overshoot phenomenon.
Department of Biochemistry, Kyoto Prefectural University of Medicine, Japan.
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Iwashima
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Kawasaki
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Kimura
D001693:Biological Transport, Active / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009154:Mutation; D011743:Pyrimidines / Q000378:metabolism* / Q000494:pharmacology; D011745:Pyrithiamine / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D013831:Thiamine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology
D011743:Pyrimidines; D011745:Pyrithiamine; C031810:4-azido-2-nitrobenzoylthiamine; C013116:2-methyl-4-amino-5-aminomethylpyrimidine; C012068:toxopyrimidine; D013831:Thiamine