Rogers T O, Lichstein H C
J Bacteriol. 1969 Nov;100(2):565-72. doi: 10.1128/jb.100.2.565-572.1969.
The metabolic control of biotin transport in Saccharomyces cerevisiae was investigated. Nonproliferating cells harvested from cultures grown in excess biotin (25 ng/ml) took up small amounts of biotin, whereas cells grown in biotin-sufficient medium (0.25 ng/ml) accumulated large amounts of the vitamin. Transport was inhibited maximally in cells grown in medium containing 9 ng (or more) of biotin per ml. When avidin was added to biotin-excess cultures, the cells developed the ability to take up large amounts of biotin. Boiled avidin was without effect, as was treatment of cells with avidin in buffer. Avidin did not relieve transport inhibition when added to biotin-excess cultures treated with cycloheximide, suggesting that protein synthesis was required for cells to develop the capacity to take up biotin after removal of extracellular vitamin by avidin. Cycloheximide did not inhibit the activity of the preformed transport system in biotin-sufficient cells. The presence of high intracellular free biotin pools did not inhibit the activity of the transport system. The characteristics of transport in biotin-excess cells (absence of temperature or pH dependence, no stimulation by glucose, absence of iodoacetate inhibition, independence of uptake on cell concentration, and nonsaturation kinetics) indicated that biotin entered these cells by diffusion. The results suggest that the synthesis of the biotin transport system in S. cerevisiae may be repressed during growth in medium containing high concentrations of biotin.
对酿酒酵母中生物素转运的代谢控制进行了研究。从在过量生物素（25 ng/ml）中培养的培养物中收获的非增殖细胞摄取少量生物素，而在生物素充足的培养基（0.25 ng/ml）中生长的细胞积累大量这种维生素。在每毫升含有9 ng（或更多）生物素的培养基中生长的细胞中，转运受到最大程度的抑制。当将抗生物素蛋白添加到生物素过量的培养物中时，细胞产生了摄取大量生物素的能力。煮沸的抗生物素蛋白没有效果，在缓冲液中用抗生物素蛋白处理细胞也没有效果。当将抗生物素蛋白添加到用环己酰亚胺处理的生物素过量培养物中时，抗生物素蛋白并不能解除转运抑制，这表明在用抗生物素蛋白去除细胞外维生素后，细胞需要蛋白质合成来发展摄取生物素的能力。环己酰亚胺并不抑制生物素充足的细胞中预先形成的转运系统的活性。高细胞内游离生物素池的存在并不抑制转运系统的活性。生物素过量细胞中的转运特征（不依赖温度或pH，不受葡萄糖刺激，不受碘乙酸抑制，摄取不依赖细胞浓度，以及非饱和动力学）表明生物素通过扩散进入这些细胞。结果表明，在含有高浓度生物素的培养基中生长期间，酿酒酵母中生物素转运系统的合成可能受到抑制。
