The nature of salicylate inhibition of sugar transport in yeast.

A study was made in yeast of the cellular site associated with inhibition of sugar transport by salicylate. Time-course and stereospecificity studies were done on the uptake of salicylic acid (sal), meta-hydroxybenzoic acid (m-OH), D-glucose (gluc) and 3-0-methyl-D-glucose (3-OMG) at 20 and 30 degrees C. Sal added simultaneously with 3-OMG had little effect on initial uptake rates of the latter. Inhibition of 3-OMG transport occurred only after appreciable uptake of sal. Rates of glucose utilization in cells preincubated with sal increased with time despite increased drug in the medium as sal decreased in the cells. Benzoic acid also inhibited 3-OMG transport. m-OH or para-hydroxybenzoic acid entered cells but neither substance inhibited 3-OMG transport nor affected the inhibition by sal of 3-OMG transport. Benzyl and salicyl alcohols had no effect on 3-OMG transport. The results indicate a stereospecific binding site or sites for sal located in the cell interior and associated with inhibition of sugar transport. The known inhibition of sugar transport by sal in susceptible mammalian cells, including human cells, may also occur through binding of sal to intracellular, stereospecific sites.