Bioprospecting of Natural Products by Use of a Heterologous Expression System in Eukaryotes

Filamentous fungi have the ability to produce a multitude of natural products that are both biologically and pharmacologically active. With advances in fungal genetics, it has paved the way for the discovery of new secondary metabolites (SM). However, many of the genes involved are silent and their products unidentifiable. Many strategies have been implemented in order to activate unknown SM gene clusters; however, it is often unsuccessful. One approach to overcome these hurdles is to heterologously express these clusters in a different organism. Reasons for doing this could range from being able to better control the expression of the cluster by implementing inducible/constitutive promoters or introducing the cluster in a host where compounds are easier identifiable. Here we present a novel strategy of combining SM gene clusters with viral genetics. The goal was to assemble a plasmid that contains an entire SM gene cluster, but in the heterologous host would be transcribed as a polycistronic mRNA. In addition, we designed 2A viral peptides between each individual gene so that they would direct cotranslational cleavage of each individual enzyme. In the end we would have each individual enzyme simultaneously expressed with the other enzymes in the pathway, meaning that all the tools for the biosynthesis of that specific product should be present and the respective product detected¹. This technique could be applied to SM gene clusters of unknown function and hopefully help in opening the door for the discovery of novel SM.

1. Unkles et al. Chemistry and Biology. 21(4):502-8 (2014).