Expression of snake venom toxins in Pichia pastoris

Snake venom is a cocktail of hundreds to thousands of biologically active proteins and enzymes used in both attack and defense. Because these proteins are capable of modulating the physiological response of envenomated animals, they show promise as potential pharmacological tools and as drug leads. In order to study function and structure relationships of snake venom proteins, many protein expression systems, including E. coli, yeast, baculovirus infected insect cells, mammalian cells, and cell-free protein synthesis, were used to produce recombinant proteins. Many venom proteins cannot be expressed in E. coli with the correct fold because most of them are highly disulfide-bonded. In contrast, many proteins have been successfully expressed in eukaryotic systems. Even though eukaryotic expression systems may allow the expression of proteins with the correct fold, they have certain disadvantages. For example, most proteins obtained from these expression systems are expensive, time consuming to produce, and are in low yield. Recently the methylotrophic yeast Pichia pastoris has drawn a lot of attention because it combines several advantages of prokaryotic and eukaryotic expression systems. It is the only system that offers the quality of E. coli like high level expression, easy scale up, and inexpensive growth medium combined with the advantages of expression in a eukaryotic system (protein processing, folding, and posttranslational modifications). Therefore, the P. pastoris expression system has been used to produce a variety of heterologous proteins. The P. pastoris system has also been widely used to express many snake venom proteins. The focus of this review will summarize the results of snake venom toxins expressed in P. pastoris.