Characterization of Schizosaccharomyces pombe mutant deficient in UDP-galactose transport activity

In fission yeast, Schizosaccharomyces pombe, the carbohydrate components of the cell mall consist of galactomannan, unlike in Saccharomyces cerevisiae . We previously found that the disruption of gms1(+), a gene encoding the U DP-galactose transporter required for the synthesis of galactomannan, led t o the complete defect of cell surface galactosylation in St. pombe. The Del ta gms1 strain is therefore useful for the analysis of physiological proper ties of galactose residues in St. pombe, The deletion strain of gms1(+) was viable; however, it shelved an aberrant cell morphology and increased sens itivities to digestion with beta -glucanase and to various drugs, such as h ygromycin B, sodium orthovanadate and Calcofluor white, A reduction of gala ctomannan layers of the cell wall in the Delta gms1 strain was observed by scanning and transmission electron microscopic analyses, The addition of os motic stabilizer suppressed the morphologic defect of the Delta gms1 cells, while other phenotypes were weakly suppressed. The Delta gms1 (h(90)) stra in was incapable of sexual conjugation during nutritional starvation. These results suggest that the cell surface galactosylation is required not only for non-sexual flocculation but also for sexual conjugation in Sz. pombe. Copyright (C) 2001 John Wiley & Sons, Ltd.