Investigation of in vivo protein interactions in Aspergillus spores

Understanding in vivo protein-protein interactions is critical to dissect precise functions of the regulatory proteins of fungal secondary metabolites. As many fungi differentially produce a diverse array of secondary metabolites during their lifecycle, it is important to understand the cell-type specific regulation of secondary metabolism. However, due to the difficulty of sample preparation of biologically active proteins in fungal spores, protein-protein interaction studies have been generally restricted. While some outstanding studies revealed protein-protein interactions of selected regulators, including the velvet proteins in vegetative cells, a detailed protocol for investigating the protein-protein interactions in the fungal spores has not yet been reported. Here, we describe a working protocol for the purification and identification of interacting protein partners of the spores of Aspergillus nidulans employing the VelB protein as an example.