The VGA3 gene from Kluyveromyces
lactis
affects secretion of endogenous and heterologous proteins as well as cell wall
properties.
Silvia Rufini (1),
Daniela Uccelletti (1), Francesca Farina (1), Claudia Abeijon (2), Claudio Palleschi
(1)
(1) Developmental and Cell Biology, University La Sapienza, P.le Aldo Moro, 5,
00185, Rome, Italy (silvia.rufini@uniroma1.it); (2) Dpt. Molecular and Cell
Biology, Boston University, Boston, MA USA.
The vga3 strain of Kluyveromyces lactis was selected as a spontaneous orthovanadate resistant mutant displaying a complex assortment of phenotypes. The N-linked glycosylation is impaired and the cell wall integrity is affected in the vga3 mutant as demonstrated by resistance to zymolyase and alteration in the amount of cell wall components. The cells are large, round and often clustered in clumps; this phenotype, however, does not appear to originate from osmotic defects since it can not be remedied by the addition of osmotic stabilizers. Here we report the isolation of the VGA3 gene as resistant to caffein and its involvement in the secretion process. In fact, the cells showed enhanced secretion of heterologous proteins and by contrast, a reduction in the secretion of endogenous proteins as invertase or acid phosphatase.