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.
Iwashima
A
A
Department of Biochemistry, Kyoto Prefectural University of Medicine, Japan.
Kawasaki
Y
Y
Kimura
Y
Y
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