THE EXPRESSION AND PERFORMANCE OF CLONED GENES IN YEASTS

Yeasts have become established as a major class of hosts for expressing cloned foreign genes, which, in terms of degree of sophistication, now rivals the fundamental host-vector systems of Escherichia coli. The successful exploitation of yeasts has resulted because they encompass a combination of important attributes. Most prominent of these is that they are eukaryotic, with consequent associated cellular processes such as protein secretion and post-translational modification activities; yet they are also single-celled and easy to manipulate, both in terms of culture and genetics. Saccharomyces cerevisiae is the most highly characterized yeast, having the most highly developed host-vector systems, and acts as a benchmark and model for other yeasts. Indeed, S. cerevisiae is the best characterized of all eukaryotes and therefore acts as a model for eukaryotes in general, since the basic functions of eukaryotic cells appear to be highly evolutionarily conserved. In this review, we examine the ways in which yeasts have been used to express cloned genes and how they perform in producing a wide range of diverse products, and the consequent impact on research and biotechnology.