Inhibition of specific amino acid uptake in Candida albicans by lysosomal extracts from rabbit alveolar macrophages.

Lysosomal-rich fractions, obtained from normal rabbit alveolar macrophages, were extracted and tested for their effects on Candida albicans. The uptake and incorporation of various compounds (amino acids, uridine, 2-deoxy-D-glucose, and Rb+) by C. albicans were measured in the presence and absence of extract. These studies demonstrated that the extract had a specific effect on the uptake of certain amino acids by C. albicans. Of the amino acids tested, the uptake of methionine valine, lysine, phenylalanine, and leucine was drastically reduced in the presence of extract, whereas proline and glutamic acid uptake was unaffected. Those amino acids whose uptake was inhibited have been shown to be transported in other yeasts by a general amino acid permease. The existence of a general amino acid permease in C. albicans is compatible with our data. Additionally, the extract had no effect on the uptake of uridine, 2-deoxy-D-glucose, and Rb+. Leakage of 86Rb by C. albicans was detected in the presence of the extract. Viability of Candida, as measured by colony-forming ability, decreased after a 16-h incubation of C. albicans with the extract.