Permeability of yeast cell envelope to fluorescent galactosylated telomersderived from THAM

The work reported herein deals with the study of cellular recognition and p ermeability phenomena in yeasts. Various galactosylated organic telomers de rived from trishydroxymethyl-aminomethane (THAM) and bearing fluorescent mo ieties were synthesized in order to measure their ability to cross the yeas t cell envelope. Grafting fluorescent probes on the organic telomer backbon e allowed us to study their specific behaviors toward the yeasts by fluores cence microscopy. Yeasts belonging to the genera Kluyveromyces and Saccharo myces were used for this study. With Saccharomyces yeast cells bearing mann ose-specific lectins or lectin-like proteins, on their outer surface, all t he galactosylated or nongalactosylated organic telomers passed through the cell envelope and invaded the cytoplasm. With Kluyveromyces yeast cells bea ring galactose-specific lectins, the galactosylated organic telomers were b lacked at the outer surface while the nongalactosylated derivatives crossed the cell envelope. Moreover, preincubation of Kluyveromyces yeasts with ga lactose or methylgalactose inhibited the cell surface anchorage of the orga nic telomers and allowed their penetration into the cytoplasm. When assays were performed on spheroplasts of both Kluyveromyces and Saccharomyces yeas ts, no fixation on the surface could be observed, and all the derivatives w ent through the membrane and invaded the cytoplasm.