IMPROVEMENTS IN THE EXPRESSION OF NEWLY INTRODUCED GENES IN YEAST CELLS

摘要

The invention relates to an improved expression system for newly introduced genes in yeast and comprises a yeast regulon, and preferably a transcription terminator, derived from one of the GAPDH genes of S. cerevisiae. The about 850 nucleotides long GAPDH regulon described proved to be almost ten times as effective as smaller regulons described previously. Said regulon and/or terminator can be introduced into yeasts either as part of plasmide molecules or by incorporating into the yeast genome. Vectors containing the expression system preferably comprises an autonomously replicating sequence derived from K. lactis (KARS) or an origin of replication originating from the S. cerevisiae 2 micron yeast plasmid. After transformation of yeasts, in particular of the genera Kluyveromyces and Saccharomyces, with said vectors, the yeasts transformed can produce foreign proteins more effectively. In the case of thaumatin the presence of a signal polypeptide (the pre-part) appears to be essential for expression in yeast. DNA sequences encoding other signal polypeptides are also described. The use of codons preferred by yeast in both structural genes, preferably those encoding thaumatin-like proteins and chymosin-like proteins, and DNA sequences encoding signal polypeptides is also described.