Growth phase dependent active transport of pyridoxine in a fission yeast, Schizosaccharomyces pombe

Schizosaccharomyces pombe showed maximum pyridoxine uptake activity around 10 h after starting cultivation. High concentrations of thiamine and pyridoxine in the medium did not affect the activity or the time but changed intracellular levels of vitamin BG compounds. Pyridoxine was taken up by a saturable mechanism with mio kinds of affinity (K-m 22.4 mu M and 118 mu M). The uptake depended on the energy produced anaerobically with an optimum pH of 4.5. The uptake was completely inhibited by amiloride, sodium azide or 2,4-dinitrophenol. The uptake system of the fission yeast was different in various respects from that of a budding yeast. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V.