M. Piontek et al., 2 NOVEL GENE-EXPRESSION SYSTEMS BASED ON THE YEASTS SCHWANNIOMYCES-OCCIDENTALIS AND PICHIA-STIPITIS, Applied microbiology and biotechnology, 50(3), 1998, pp. 331-338
Two non-Saccharomyces yeasts have been developed as hosts for heterolo
gous gene expression. The celD gene from Clostridium thermocellum, enc
oding a heat-stable cellulase, served as the test sequence. The first
system is based on the amylolytic species Schwanniomyces occidentalis,
the second on the xylolytic species Pichia stipitis. The systems comp
rise auxotrophic host strains (trp5 in the case of S. occidentalis; tr
p5-10, his3 in the case of P. stipitis) and suitable transformation ve
ctors. Vector components consist of an S. occidentalis-derived autonom
ously replicating sequence (SwARS) and the Saccharomyces cerevisiae-de
rived TRP5 sequence for plasmid propagation and selection in the yeast
hosts, an ori and an ampicillin-resistance sequence for propagation a
nd selection in a bacterial host. A range of vectors has been engineer
ed employing different promoter elements for heterologous gene express
ion control in both species. Homologous elements derived from highly e
xpressed genes of the respective hosts appeared to be of superior qual
ity: in the case of S, occidentalis that of the GAM1 gene, in the case
of P. stipitis that of the XYL1 gene. Further elements tested are the
S. cerevisiae-derived ADH1 and PDC1 promoter sequences.