F del Rey

Heterogeneous glycosylation of the EXG1 gene product accounts for the two extracellular exo-β-glucanases of Saccharomyces cerevisiae

Two exo‐β‐glucanases of glycoprotein nature can be detected in culture supernatants of Saccharomyces cerevisiae cells. These exo‐β‐glucanases show different M r values and kinetic properties, although they are immunologically related. Their carbohydrate content and the electrophoretic mobility of both endoglycosidase H‐treated exo‐β‐glucanases suggest that they share the same protein fraction. Studies at genetic level relate the production of both extracellular exo‐β‐glucanases with the expression of a single‐copy gene in S. cerevisiae. Expression of this gene in another yeast, Schizosaccharomyces pombe, demonstrates that it codes for a protein with exo‐β‐glucanase activity whose heterogeneous N‐glycosylation accounts for both extracellular exo‐β‐glucanases of S. cerevisiae.

The NUD1 Gene of Yeast Saccharomyces Cerevisiae Complements a Thermosensitive Lytic Mutation

ABSTRACT Temperature sensitive (ts) yeast strains have been obtained by ethyl methane sulfonate (EMS) mutagenesis. They have a normal growth at low temperature and releases of intracellular proteins in the culture medium at 37°C. The ts mutation was localized in the NUD1 gene, which codes for a component of the yeast spindle pole body (SPB). Construction of a frame shift mutation in the wild type gene demonstrated that the correct sequence of the NUD1 gene only could complement the ts phenotype. Further analysis showed that the ts mutation deprived the cells of a normal termination of mitosis, thus causing death at restrictive temperature and a consequence cell lysis.