Characteristics of Saccharomyces cerevisiae gal1 Delta and gal1 Delta hxk2 Delta mutants expressing recombinant proteins from the GAL promoter.
Galactose can be used not only as an inducer of the GAL promoters, but also as a carbon source by Saccharomyces cerevisiae, which makes recombinant fermentation processes that use GAL promoters complicated and expensive. To overcome this problem during the cultivation of the recombinant strain expressing human serum albumin (HSA) from the GAL10 promoter, a gal1 Delta mutant strain was constructed and its induction kinetics investigated. As expected, the gal1 Delta strain did not use galactose, and showed high levels of HSA expression, even at extremely low galactose concentrations (0.05-0.1 g/L). However, the gal1 Delta strain produced much more ethanol, in a complex medium containing glucose, than the GAL1 strain. To improve the physiological properties of the gal1 Delta mutant strain as a host for heterologous protein production, a null mutation of either MIG1 or HXK2 was introduced into the gal1 Delta mutant strain, generating gal1 Delta mig1 Delta and gal1 Delta hxk2 Delta double strains. The gal1 Delta hxk2 Delta strain showed a decreased rate of ethanol synthesis, with an accelerated rate of ethanol consumption, compared to the gal1 Delta strain, whereas the gal1 Delta mig1 Delta strain showed similar patterns to the gal1 Delta strain. Furthermore, the gal1 Delta hxk2 Delta strain secreted much more recombinant proteins (HSA and HSA fusion proteins) than the other strains. The results suggest that the gal1 Delta hxk2 Delta strain would be useful for the large-scale production of heterologous proteins from the GAL10 promoter in S. cerevisiae.
Kang
Hyun Ah
HA
Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-333, Korea.
Kang
Woo Kyu
WK
Go
Su-Min
SM
Rezaee
Abbas
A
Krishna
Sajja Hari
SH
Rhee
Sang Ki
SK
Kim
Jeong-Yoon
JY
D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005690:Galactose / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D005818:Genetic Engineering; D006593:Hexokinase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D009154:Mutation; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D012709:Serum Albumin / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; C085976:MIG1 protein, S cerevisiae; D011994:Recombinant Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D012709:Serum Albumin; D000431:Ethanol; D006593:Hexokinase; D005690:Galactose